16232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson/* 26232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Written by Doug Lea with assistance from members of JCP JSR-166 36232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Expert Group and released to the public domain, as explained at 4a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * http://creativecommons.org/publicdomain/zero/1.0/ 56232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 66232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 76232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilsonpackage java.util.concurrent.locks; 8aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath 991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravleimport java.util.ArrayList; 1091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravleimport java.util.Collection; 1191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravleimport java.util.Date; 12e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniakimport java.util.concurrent.TimeUnit; 13e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniakimport java.util.concurrent.locks.AbstractQueuedSynchronizer.Node; 146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson/** 166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * A version of {@link AbstractQueuedSynchronizer} in 1791770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * which synchronization state is maintained as a {@code long}. 186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * This class has exactly the same structure, properties, and methods 1991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * as {@code AbstractQueuedSynchronizer} with the exception 206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * that all state-related parameters and results are defined 2191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * as {@code long} rather than {@code int}. This class 226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * may be useful when creating synchronizers such as 236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * multilevel locks and barriers that require 246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 64 bits of state. 256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>See {@link AbstractQueuedSynchronizer} for usage 276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * notes and examples. 286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @since 1.6 306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @author Doug Lea 316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilsonpublic abstract class AbstractQueuedLongSynchronizer 336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson extends AbstractOwnableSynchronizer 346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson implements java.io.Serializable { 356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private static final long serialVersionUID = 7373984972572414692L; 376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson To keep sources in sync, the remainder of this source file is 406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson exactly cloned from AbstractQueuedSynchronizer, replacing class 416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson name and changing ints related with sync state to longs. Please 426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson keep it that way. 436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Creates a new {@code AbstractQueuedLongSynchronizer} instance 476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * with initial synchronization state of zero. 486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected AbstractQueuedLongSynchronizer() { } 506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Head of the wait queue, lazily initialized. Except for 536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * initialization, it is modified only via method setHead. Note: 546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * If head exists, its waitStatus is guaranteed not to be 556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * CANCELLED. 566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private transient volatile Node head; 586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Tail of the wait queue, lazily initialized. Modified only via 616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * method enq to add new wait node. 626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private transient volatile Node tail; 646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The synchronization state. 676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private volatile long state; 696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns the current value of synchronization state. 7291770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * This operation has memory semantics of a {@code volatile} read. 736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return current state value 746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final long getState() { 766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return state; 776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Sets the value of synchronization state. 8191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * This operation has memory semantics of a {@code volatile} write. 826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param newState the new state value 836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final void setState(long newState) { 85e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // Use putLongVolatile instead of ordinary volatile store when 86e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // using compareAndSwapLong, for sake of some 32bit systems. 87e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak U.putLongVolatile(this, STATE, newState); 886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Atomically sets synchronization state to the given updated 926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * value if the current state value equals the expected value. 9391770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * This operation has memory semantics of a {@code volatile} read 946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and write. 956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param expect the expected value 976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param update the new value 98e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * @return {@code true} if successful. False return indicates that the actual 996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * value was not equal to the expected value. 1006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final boolean compareAndSetState(long expect, long update) { 102e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak return U.compareAndSwapLong(this, STATE, expect, update); 1036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Queuing utilities 1066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The number of nanoseconds for which it is faster to spin 1096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * rather than to use timed park. A rough estimate suffices 1106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to improve responsiveness with very short timeouts. 1116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 112e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak static final long SPIN_FOR_TIMEOUT_THRESHOLD = 1000L; 1136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Inserts node into queue, initializing if necessary. See picture above. 1166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node to insert 1176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return node's predecessor 1186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 119e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private Node enq(Node node) { 1206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 121e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Node oldTail = tail; 122e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (oldTail != null) { 123e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak U.putObject(node, Node.PREV, oldTail); 124e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (compareAndSetTail(oldTail, node)) { 125e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak oldTail.next = node; 126e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak return oldTail; 1276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 128e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } else { 129e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak initializeSyncQueue(); 1306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Creates and enqueues node for current thread and given mode. 1366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param mode Node.EXCLUSIVE for exclusive, Node.SHARED for shared 1386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the new node 1396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private Node addWaiter(Node mode) { 141e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Node node = new Node(mode); 142e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak 143e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak for (;;) { 144e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Node oldTail = tail; 145e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (oldTail != null) { 146e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak U.putObject(node, Node.PREV, oldTail); 147e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (compareAndSetTail(oldTail, node)) { 148e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak oldTail.next = node; 149e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak return node; 150e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } 151e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } else { 152e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak initializeSyncQueue(); 1536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Sets head of queue to be node, thus dequeuing. Called only by 1596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire methods. Also nulls out unused fields for sake of GC 1606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and to suppress unnecessary signals and traversals. 1616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 1636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void setHead(Node node) { 1656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson head = node; 1666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.thread = null; 1676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.prev = null; 1686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Wakes up node's successor, if one exists. 1726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 1746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void unparkSuccessor(Node node) { 1766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 1776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * If status is negative (i.e., possibly needing signal) try 1786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to clear in anticipation of signalling. It is OK if this 1796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * fails or if status is changed by waiting thread. 1806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int ws = node.waitStatus; 1826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (ws < 0) 183e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak node.compareAndSetWaitStatus(ws, 0); 1846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 1856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 1866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Thread to unpark is held in successor, which is normally 1876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * just the next node. But if cancelled or apparently null, 1886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * traverse backwards from tail to find the actual 1896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * non-cancelled successor. 1906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node s = node.next; 1926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (s == null || s.waitStatus > 0) { 1936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson s = null; 194e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak for (Node p = tail; p != node && p != null; p = p.prev) 195aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath if (p.waitStatus <= 0) 196aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath s = p; 1976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (s != null) 1996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.unpark(s.thread); 2006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 20391770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Release action for shared mode -- signals successor and ensures 2046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * propagation. (Note: For exclusive mode, release just amounts 2056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to calling unparkSuccessor of head if it needs signal.) 2066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doReleaseShared() { 2086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 2096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Ensure that a release propagates, even if there are other 2106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * in-progress acquires/releases. This proceeds in the usual 2116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * way of trying to unparkSuccessor of head if it needs 2126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * signal. But if it does not, status is set to PROPAGATE to 2136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * ensure that upon release, propagation continues. 2146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Additionally, we must loop in case a new node is added 2156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * while we are doing this. Also, unlike other uses of 2166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * unparkSuccessor, we need to know if CAS to reset status 2176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * fails, if so rechecking. 2186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 2206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h = head; 2216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (h != null && h != tail) { 2226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int ws = h.waitStatus; 2236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (ws == Node.SIGNAL) { 224e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (!h.compareAndSetWaitStatus(Node.SIGNAL, 0)) 2256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson continue; // loop to recheck cases 2266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unparkSuccessor(h); 2276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson else if (ws == 0 && 229e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak !h.compareAndSetWaitStatus(0, Node.PROPAGATE)) 2306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson continue; // loop on failed CAS 2316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (h == head) // loop if head changed 2336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 2346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Sets head of queue, and checks if successor may be waiting 2396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * in shared mode, if so propagating if either propagate > 0 or 2406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * PROPAGATE status was set. 2416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 2436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param propagate the return value from a tryAcquireShared 2446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void setHeadAndPropagate(Node node, long propagate) { 2466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h = head; // Record old head for check below 2476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHead(node); 2486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 2496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Try to signal next queued node if: 2506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Propagation was indicated by caller, 251e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * or was recorded (as h.waitStatus either before 252e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * or after setHead) by a previous operation 2536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * (note: this uses sign-check of waitStatus because 2546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * PROPAGATE status may transition to SIGNAL.) 2556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and 2566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The next node is waiting in shared mode, 2576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * or we don't know, because it appears null 2586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The conservatism in both of these checks may cause 2606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * unnecessary wake-ups, but only when there are multiple 2616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * racing acquires/releases, so most need signals now or soon 2626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * anyway. 2636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 264e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (propagate > 0 || h == null || h.waitStatus < 0 || 265e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak (h = head) == null || h.waitStatus < 0) { 2666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node s = node.next; 2676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (s == null || s.isShared()) 2686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doReleaseShared(); 2696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 2716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Utilities for various versions of acquire 2736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 2756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Cancels an ongoing attempt to acquire. 2766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 2776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 2786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 2796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void cancelAcquire(Node node) { 2806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Ignore if node doesn't exist 2816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node == null) 2826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return; 2836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.thread = null; 2856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Skip cancelled predecessors 2876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node pred = node.prev; 2886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (pred.waitStatus > 0) 2896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.prev = pred = pred.prev; 2906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // predNext is the apparent node to unsplice. CASes below will 2926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // fail if not, in which case, we lost race vs another cancel 2936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // or signal, so no further action is necessary. 2946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node predNext = pred.next; 2956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 2966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Can use unconditional write instead of CAS here. 2976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // After this atomic step, other Nodes can skip past us. 2986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Before, we are free of interference from other threads. 2996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.waitStatus = Node.CANCELLED; 3006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // If we are the tail, remove ourselves. 3026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node == tail && compareAndSetTail(node, pred)) { 303e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak pred.compareAndSetNext(predNext, null); 3046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } else { 3056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // If successor needs signal, try to set pred's next-link 3066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // so it will get one. Otherwise wake it up to propagate. 3076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int ws; 3086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (pred != head && 3096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson ((ws = pred.waitStatus) == Node.SIGNAL || 310e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak (ws <= 0 && pred.compareAndSetWaitStatus(ws, Node.SIGNAL))) && 3116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson pred.thread != null) { 3126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node next = node.next; 3136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (next != null && next.waitStatus <= 0) 314e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak pred.compareAndSetNext(predNext, next); 3156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } else { 3166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unparkSuccessor(node); 3176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.next = node; // help GC 3206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Checks and updates status for a node that failed to acquire. 3256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if thread should block. This is the main signal 32691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * control in all acquire loops. Requires that pred == node.prev. 3276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param pred node's predecessor holding status 3296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 3306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if thread should block 3316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private static boolean shouldParkAfterFailedAcquire(Node pred, Node node) { 3336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int ws = pred.waitStatus; 3346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (ws == Node.SIGNAL) 3356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 3366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * This node has already set status asking a release 3376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to signal it, so it can safely park. 3386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 3406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (ws > 0) { 3416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 3426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Predecessor was cancelled. Skip over predecessors and 3436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * indicate retry. 3446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson do { 3466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson node.prev = pred = pred.prev; 3476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } while (pred.waitStatus > 0); 3486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson pred.next = node; 3496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } else { 3506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 3516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * waitStatus must be 0 or PROPAGATE. Indicate that we 3526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * need a signal, but don't park yet. Caller will need to 3536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * retry to make sure it cannot acquire before parking. 3546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 355e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak pred.compareAndSetWaitStatus(ws, Node.SIGNAL); 3566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 3586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Convenience method to interrupt current thread. 3626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 363a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson static void selfInterrupt() { 3646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread.currentThread().interrupt(); 3656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 368e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Convenience method to park and then check if interrupted. 3696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if interrupted 3716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private final boolean parkAndCheckInterrupt() { 3736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.park(this); 3746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return Thread.interrupted(); 3756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 3766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 3786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Various flavors of acquire, varying in exclusive/shared and 3796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * control modes. Each is mostly the same, but annoyingly 3806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * different. Only a little bit of factoring is possible due to 3816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * interactions of exception mechanics (including ensuring that we 3826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * cancel if tryAcquire throws exception) and other control, at 3836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * least not without hurting performance too much. 3846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 3866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 3876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in exclusive uninterruptible mode for thread already in 3886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * queue. Used by condition wait methods as well as acquire. 3896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 3906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 3916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 3926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if interrupted while waiting 3936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 3946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean acquireQueued(final Node node, long arg) { 3956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 3966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean interrupted = false; 3976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 3986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 3996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head && tryAcquire(arg)) { 4006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHead(node); 4016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 4026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return interrupted; 4036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 4056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson parkAndCheckInterrupt()) 4066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interrupted = true; 4076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 408e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 409e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 410e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 4116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 4146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in exclusive interruptible mode. 4166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 4176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 4186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doAcquireInterruptibly(long arg) 4196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throws InterruptedException { 4206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node node = addWaiter(Node.EXCLUSIVE); 4216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 4226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 4236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 4246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head && tryAcquire(arg)) { 4256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHead(node); 4266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 4276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return; 4286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 4306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson parkAndCheckInterrupt()) 4316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 4326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 433e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 434e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 435e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 4366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 4396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in exclusive timed mode. 4416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 4426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 4436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param nanosTimeout max wait time 4446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if acquired 4456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 4466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private boolean doAcquireNanos(long arg, long nanosTimeout) 44791770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle throws InterruptedException { 44891770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle if (nanosTimeout <= 0L) 44991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle return false; 45091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle final long deadline = System.nanoTime() + nanosTimeout; 4516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node node = addWaiter(Node.EXCLUSIVE); 4526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 4536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 4546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 4556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head && tryAcquire(arg)) { 4566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHead(node); 4576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 4586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 4596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 46091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle nanosTimeout = deadline - System.nanoTime(); 461e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (nanosTimeout <= 0L) { 462e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 4636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 464e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } 4656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 466e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak nanosTimeout > SPIN_FOR_TIMEOUT_THRESHOLD) 4676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.parkNanos(this, nanosTimeout); 4686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 4696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 4706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 471e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 472e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 473e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 4746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 4776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 4786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in shared uninterruptible mode. 4796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 4806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 4816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doAcquireShared(long arg) { 4826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node node = addWaiter(Node.SHARED); 4836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 4846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean interrupted = false; 4856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 4866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 4876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head) { 4886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long r = tryAcquireShared(arg); 4896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (r >= 0) { 4906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHeadAndPropagate(node, r); 4916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 4926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interrupted) 4936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson selfInterrupt(); 4946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return; 4956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 4976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 4986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson parkAndCheckInterrupt()) 4996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interrupted = true; 5006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 501e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 502e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 503e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 5046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 5076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 5086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in shared interruptible mode. 5096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 5106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 5116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doAcquireSharedInterruptibly(long arg) 5126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throws InterruptedException { 5136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node node = addWaiter(Node.SHARED); 5146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 5156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 5166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 5176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head) { 5186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long r = tryAcquireShared(arg); 5196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (r >= 0) { 5206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHeadAndPropagate(node, r); 5216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 5226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return; 5236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 5266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson parkAndCheckInterrupt()) 5276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 5286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 529e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 530e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 531e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 5326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 5356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 5366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in shared timed mode. 5376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 5386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument 5396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param nanosTimeout max wait time 5406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if acquired 5416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 5426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private boolean doAcquireSharedNanos(long arg, long nanosTimeout) 54391770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle throws InterruptedException { 54491770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle if (nanosTimeout <= 0L) 54591770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle return false; 54691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle final long deadline = System.nanoTime() + nanosTimeout; 5476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node node = addWaiter(Node.SHARED); 5486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 5496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (;;) { 5506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final Node p = node.predecessor(); 5516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p == head) { 5526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long r = tryAcquireShared(arg); 5536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (r >= 0) { 5546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson setHeadAndPropagate(node, r); 5556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson p.next = null; // help GC 5566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 5576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 55991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle nanosTimeout = deadline - System.nanoTime(); 560e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (nanosTimeout <= 0L) { 561e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 5626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 563e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } 5646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (shouldParkAfterFailedAcquire(p, node) && 565e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak nanosTimeout > SPIN_FOR_TIMEOUT_THRESHOLD) 5666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.parkNanos(this, nanosTimeout); 5676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 5686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 5696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 570e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 571e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak cancelAcquire(node); 572e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 5736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 5756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 5766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Main exported methods 5776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 5786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 5796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to acquire in exclusive mode. This method should query 5806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * if the state of the object permits it to be acquired in the 5816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * exclusive mode, and if so to acquire it. 5826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 5836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This method is always invoked by the thread performing 5846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire. If this method reports failure, the acquire method 5856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * may queue the thread, if it is not already queued, until it is 5866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * signalled by a release from some other thread. This can be used 5876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to implement method {@link Lock#tryLock()}. 5886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 5896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>The default 5906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * implementation throws {@link UnsupportedOperationException}. 5916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 5926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is always the one 5936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * passed to an acquire method, or is the value saved on entry 5946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to a condition wait. The value is otherwise uninterpreted 5956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and can represent anything you like. 5966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if successful. Upon success, this object has 5976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * been acquired. 5986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if acquiring would place this 5996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer in an illegal state. This exception must be 6006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thrown in a consistent fashion for synchronization to work 6016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * correctly. 6026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws UnsupportedOperationException if exclusive mode is not supported 6036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 6046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected boolean tryAcquire(long arg) { 6056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new UnsupportedOperationException(); 6066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 6076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 6086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 6096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to set the state to reflect a release in exclusive 6106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * mode. 6116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This method is always invoked by the thread performing release. 6136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>The default implementation throws 6156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link UnsupportedOperationException}. 6166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the release argument. This value is always the one 6186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * passed to a release method, or the current state value upon 6196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * entry to a condition wait. The value is otherwise 6206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * uninterpreted and can represent anything you like. 6216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if this object is now in a fully released 6226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * state, so that any waiting threads may attempt to acquire; 6236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and {@code false} otherwise. 6246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if releasing would place this 6256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer in an illegal state. This exception must be 6266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thrown in a consistent fashion for synchronization to work 6276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * correctly. 6286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws UnsupportedOperationException if exclusive mode is not supported 6296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 6306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected boolean tryRelease(long arg) { 6316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new UnsupportedOperationException(); 6326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 6336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 6346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 6356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to acquire in shared mode. This method should query if 6366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * the state of the object permits it to be acquired in the shared 6376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * mode, and if so to acquire it. 6386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This method is always invoked by the thread performing 6406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire. If this method reports failure, the acquire method 6416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * may queue the thread, if it is not already queued, until it is 6426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * signalled by a release from some other thread. 6436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>The default implementation throws {@link 6456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * UnsupportedOperationException}. 6466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is always the one 6486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * passed to an acquire method, or is the value saved on entry 6496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to a condition wait. The value is otherwise uninterpreted 6506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and can represent anything you like. 6516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return a negative value on failure; zero if acquisition in shared 6526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * mode succeeded but no subsequent shared-mode acquire can 6536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * succeed; and a positive value if acquisition in shared 6546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * mode succeeded and subsequent shared-mode acquires might 6556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * also succeed, in which case a subsequent waiting thread 6566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * must check availability. (Support for three different 6576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * return values enables this method to be used in contexts 6586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * where acquires only sometimes act exclusively.) Upon 6596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * success, this object has been acquired. 6606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if acquiring would place this 6616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer in an illegal state. This exception must be 6626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thrown in a consistent fashion for synchronization to work 6636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * correctly. 6646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws UnsupportedOperationException if shared mode is not supported 6656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 6666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected long tryAcquireShared(long arg) { 6676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new UnsupportedOperationException(); 6686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 6696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 6706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 6716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to set the state to reflect a release in shared mode. 6726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This method is always invoked by the thread performing release. 6746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>The default implementation throws 6766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link UnsupportedOperationException}. 6776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 6786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the release argument. This value is always the one 6796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * passed to a release method, or the current state value upon 6806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * entry to a condition wait. The value is otherwise 6816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * uninterpreted and can represent anything you like. 6826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if this release of shared mode may permit a 6836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * waiting acquire (shared or exclusive) to succeed; and 6846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code false} otherwise 6856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if releasing would place this 6866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer in an illegal state. This exception must be 6876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thrown in a consistent fashion for synchronization to work 6886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * correctly. 6896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws UnsupportedOperationException if shared mode is not supported 6906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 6916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected boolean tryReleaseShared(long arg) { 6926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new UnsupportedOperationException(); 6936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 6946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 6956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 6966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns {@code true} if synchronization is held exclusively with 6976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * respect to the current (calling) thread. This method is invoked 6986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * upon each call to a non-waiting {@link ConditionObject} method. 6996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * (Waiting methods instead invoke {@link #release}.) 7006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>The default implementation throws {@link 7026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * UnsupportedOperationException}. This method is invoked 7036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * internally only within {@link ConditionObject} methods, so need 7046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * not be defined if conditions are not used. 7056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if synchronization is held exclusively; 7076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code false} otherwise 7086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws UnsupportedOperationException if conditions are not supported 7096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 7106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected boolean isHeldExclusively() { 7116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new UnsupportedOperationException(); 7126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 7146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 7156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in exclusive mode, ignoring interrupts. Implemented 7166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * by invoking at least once {@link #tryAcquire}, 7176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returning on success. Otherwise the thread is queued, possibly 7186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * repeatedly blocking and unblocking, invoking {@link 7196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * #tryAcquire} until success. This method can be used 7206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to implement method {@link Lock#lock}. 7216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is conveyed to 7236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquire} but is otherwise uninterpreted and 7246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * can represent anything you like. 7256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 7266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void acquire(long arg) { 7276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!tryAcquire(arg) && 7286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson acquireQueued(addWaiter(Node.EXCLUSIVE), arg)) 7296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson selfInterrupt(); 7306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 7326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 7336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in exclusive mode, aborting if interrupted. 7346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implemented by first checking interrupt status, then invoking 7356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * at least once {@link #tryAcquire}, returning on 7366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * success. Otherwise the thread is queued, possibly repeatedly 7376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * blocking and unblocking, invoking {@link #tryAcquire} 7386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * until success or the thread is interrupted. This method can be 7396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * used to implement method {@link Lock#lockInterruptibly}. 7406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is conveyed to 7426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquire} but is otherwise uninterpreted and 7436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * can represent anything you like. 7446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws InterruptedException if the current thread is interrupted 7456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 7468eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final void acquireInterruptibly(long arg) 7478eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 7486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 7496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 7506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!tryAcquire(arg)) 7516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doAcquireInterruptibly(arg); 7526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 7546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 7556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to acquire in exclusive mode, aborting if interrupted, 7566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and failing if the given timeout elapses. Implemented by first 7576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * checking interrupt status, then invoking at least once {@link 7586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * #tryAcquire}, returning on success. Otherwise, the thread is 7596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * queued, possibly repeatedly blocking and unblocking, invoking 7606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquire} until success or the thread is interrupted 7616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * or the timeout elapses. This method can be used to implement 7626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * method {@link Lock#tryLock(long, TimeUnit)}. 7636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is conveyed to 7656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquire} but is otherwise uninterpreted and 7666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * can represent anything you like. 7676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param nanosTimeout the maximum number of nanoseconds to wait 7686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if acquired; {@code false} if timed out 7696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws InterruptedException if the current thread is interrupted 7706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 7718eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final boolean tryAcquireNanos(long arg, long nanosTimeout) 7728eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 7736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 7746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 7756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return tryAcquire(arg) || 7766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doAcquireNanos(arg, nanosTimeout); 7776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 7796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 7806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Releases in exclusive mode. Implemented by unblocking one or 7816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * more threads if {@link #tryRelease} returns true. 7826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * This method can be used to implement method {@link Lock#unlock}. 7836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 7846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the release argument. This value is conveyed to 7856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryRelease} but is otherwise uninterpreted and 7866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * can represent anything you like. 7876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the value returned from {@link #tryRelease} 7886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 7896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean release(long arg) { 7906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (tryRelease(arg)) { 7916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h = head; 7926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (h != null && h.waitStatus != 0) 7936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unparkSuccessor(h); 7946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 7956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 7976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 7986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 7996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in shared mode, ignoring interrupts. Implemented by 8016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * first invoking at least once {@link #tryAcquireShared}, 8026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returning on success. Otherwise the thread is queued, possibly 8036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * repeatedly blocking and unblocking, invoking {@link 8046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * #tryAcquireShared} until success. 8056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is conveyed to 8076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquireShared} but is otherwise uninterpreted 8086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and can represent anything you like. 8096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 8106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void acquireShared(long arg) { 8116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (tryAcquireShared(arg) < 0) 8126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doAcquireShared(arg); 8136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Acquires in shared mode, aborting if interrupted. Implemented 8176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * by first checking interrupt status, then invoking at least once 8186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquireShared}, returning on success. Otherwise the 8196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thread is queued, possibly repeatedly blocking and unblocking, 8206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * invoking {@link #tryAcquireShared} until success or the thread 8216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is interrupted. 82291770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * @param arg the acquire argument. 8236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * This value is conveyed to {@link #tryAcquireShared} but is 8246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * otherwise uninterpreted and can represent anything 8256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * you like. 8266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws InterruptedException if the current thread is interrupted 8276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 8288eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final void acquireSharedInterruptibly(long arg) 8298eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 8306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 8316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 8326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (tryAcquireShared(arg) < 0) 8336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doAcquireSharedInterruptibly(arg); 8346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Attempts to acquire in shared mode, aborting if interrupted, and 8386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * failing if the given timeout elapses. Implemented by first 8396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * checking interrupt status, then invoking at least once {@link 8406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * #tryAcquireShared}, returning on success. Otherwise, the 8416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thread is queued, possibly repeatedly blocking and unblocking, 8426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * invoking {@link #tryAcquireShared} until success or the thread 8436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is interrupted or the timeout elapses. 8446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the acquire argument. This value is conveyed to 8466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryAcquireShared} but is otherwise uninterpreted 8476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and can represent anything you like. 8486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param nanosTimeout the maximum number of nanoseconds to wait 8496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if acquired; {@code false} if timed out 8506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws InterruptedException if the current thread is interrupted 8516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 8528eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final boolean tryAcquireSharedNanos(long arg, long nanosTimeout) 8538eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 8546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 8556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 8566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return tryAcquireShared(arg) >= 0 || 8576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doAcquireSharedNanos(arg, nanosTimeout); 8586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Releases in shared mode. Implemented by unblocking one or more 8626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * threads if {@link #tryReleaseShared} returns true. 8636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param arg the release argument. This value is conveyed to 8656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@link #tryReleaseShared} but is otherwise uninterpreted 8666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and can represent anything you like. 8676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the value returned from {@link #tryReleaseShared} 8686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 8696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean releaseShared(long arg) { 8706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (tryReleaseShared(arg)) { 8716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doReleaseShared(); 8726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 8736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 8756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Queue inspection methods 8786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether any threads are waiting to acquire. Note that 8816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * because cancellations due to interrupts and timeouts may occur 8826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * at any time, a {@code true} return does not guarantee that any 8836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * other thread will ever acquire. 8846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>In this implementation, this operation returns in 8866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * constant time. 8876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if there may be other threads waiting to acquire 8896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 8906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean hasQueuedThreads() { 8916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return head != tail; 8926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 8936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 8946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 8956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether any threads have ever contended to acquire this 896e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * synchronizer; that is, if an acquire method has ever blocked. 8976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 8986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>In this implementation, this operation returns in 8996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * constant time. 9006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 9016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if there has ever been contention 9026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean hasContended() { 9046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return head != null; 9056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 9086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns the first (longest-waiting) thread in the queue, or 9096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code null} if no threads are currently queued. 9106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 9116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>In this implementation, this operation normally returns in 9126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * constant time, but may iterate upon contention if other threads are 9136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * concurrently modifying the queue. 9146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 9156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the first (longest-waiting) thread in the queue, or 9166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code null} if no threads are currently queued 9176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final Thread getFirstQueuedThread() { 9196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // handle only fast path, else relay 9206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return (head == tail) ? null : fullGetFirstQueuedThread(); 9216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 924e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Version of getFirstQueuedThread called when fastpath fails. 9256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private Thread fullGetFirstQueuedThread() { 9276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 9286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The first node is normally head.next. Try to get its 9296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thread field, ensuring consistent reads: If thread 9306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * field is nulled out or s.prev is no longer head, then 9316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * some other thread(s) concurrently performed setHead in 9326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * between some of our reads. We try this twice before 9336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * resorting to traversal. 9346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h, s; 9366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread st; 9376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (((h = head) != null && (s = h.next) != null && 9386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson s.prev == head && (st = s.thread) != null) || 9396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson ((h = head) != null && (s = h.next) != null && 9406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson s.prev == head && (st = s.thread) != null)) 9416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return st; 9426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 9446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Head's next field might not have been set yet, or may have 9456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * been unset after setHead. So we must check to see if tail 9466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is actually first node. If not, we continue on, safely 9476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * traversing from tail back to head to find first, 9486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * guaranteeing termination. 9496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread firstThread = null; 952e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak for (Node p = tail; p != null && p != head; p = p.prev) { 953e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Thread t = p.thread; 954e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (t != null) 955e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak firstThread = t; 9566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return firstThread; 9586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 9616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if the given thread is currently queued. 9626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 9636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This implementation traverses the queue to determine 9646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * presence of the given thread. 9656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 9666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param thread the thread 9676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if the given thread is on the queue 9686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws NullPointerException if the thread is null 9696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean isQueued(Thread thread) { 9716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (thread == null) 9726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new NullPointerException(); 9736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node p = tail; p != null; p = p.prev) 9746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p.thread == thread) 9756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 9766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 9776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 9806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns {@code true} if the apparent first queued thread, if one 9816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * exists, is waiting in exclusive mode. If this method returns 9826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code true}, and the current thread is attempting to acquire in 9836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * shared mode (that is, this method is invoked from {@link 9846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * #tryAcquireShared}) then it is guaranteed that the current thread 9856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is not the first queued thread. Used only as a heuristic in 9866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * ReentrantReadWriteLock. 9876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 9886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean apparentlyFirstQueuedIsExclusive() { 9896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h, s; 9906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return (h = head) != null && 9916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (s = h.next) != null && 9926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson !s.isShared() && 9936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson s.thread != null; 9946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 9956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 9966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 9976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether any threads have been waiting to acquire longer 9986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * than the current thread. 9996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>An invocation of this method is equivalent to (but may be 10016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * more efficient than): 1002e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <pre> {@code 1003e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * getFirstQueuedThread() != Thread.currentThread() 1004e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * && hasQueuedThreads()}</pre> 10056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>Note that because cancellations due to interrupts and 10076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * timeouts may occur at any time, a {@code true} return does not 10086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * guarantee that some other thread will acquire before the current 10096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * thread. Likewise, it is possible for another thread to win a 10106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * race to enqueue after this method has returned {@code false}, 10116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * due to the queue being empty. 10126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This method is designed to be used by a fair synchronizer to 1014a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * avoid <a href="AbstractQueuedSynchronizer.html#barging">barging</a>. 10156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Such a synchronizer's {@link #tryAcquire} method should return 10166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code false}, and its {@link #tryAcquireShared} method should 10176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * return a negative value, if this method returns {@code true} 10186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * (unless this is a reentrant acquire). For example, the {@code 10196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * tryAcquire} method for a fair, reentrant, exclusive mode 10206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer might look like this: 10216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 1022e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <pre> {@code 10236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * protected boolean tryAcquire(int arg) { 10246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * if (isHeldExclusively()) { 10256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * // A reentrant acquire; increment hold count 10266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * return true; 10276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * } else if (hasQueuedPredecessors()) { 10286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * return false; 10296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * } else { 10306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * // try to acquire normally 10316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * } 10326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * }}</pre> 10336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if there is a queued thread preceding the 10356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * current thread, and {@code false} if the current thread 10366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is at the head of the queue or the queue is empty 10376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @since 1.7 10386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 103991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle public final boolean hasQueuedPredecessors() { 10406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // The correctness of this depends on head being initialized 10416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // before tail and on head.next being accurate if the current 10426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // thread is first in queue. 10436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node t = tail; // Read fields in reverse initialization order 10446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node h = head; 10456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node s; 10466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return h != t && 10476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson ((s = h.next) == null || s.thread != Thread.currentThread()); 10486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 10496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 10506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 10516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Instrumentation and monitoring methods 10526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 10536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 10546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns an estimate of the number of threads waiting to 10556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire. The value is only an estimate because the number of 10566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * threads may change dynamically while this method traverses 10576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * internal data structures. This method is designed for use in 1058e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * monitoring system state, not for synchronization control. 10596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the estimated number of threads waiting to acquire 10616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 10626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final int getQueueLength() { 10636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int n = 0; 10646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node p = tail; p != null; p = p.prev) { 10656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p.thread != null) 10666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson ++n; 10676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 10686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return n; 10696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 10706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 10716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 10726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a collection containing threads that may be waiting to 10736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire. Because the actual set of threads may change 10746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * dynamically while constructing this result, the returned 10756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * collection is only a best-effort estimate. The elements of the 10766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returned collection are in no particular order. This method is 10776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * designed to facilitate construction of subclasses that provide 10786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * more extensive monitoring facilities. 10796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the collection of threads 10816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 10826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final Collection<Thread> getQueuedThreads() { 1083e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak ArrayList<Thread> list = new ArrayList<>(); 10846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node p = tail; p != null; p = p.prev) { 10856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread t = p.thread; 10866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t != null) 10876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson list.add(t); 10886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 10896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return list; 10906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 10916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 10926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 10936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a collection containing threads that may be waiting to 10946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire in exclusive mode. This has the same properties 10956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * as {@link #getQueuedThreads} except that it only returns 10966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * those threads waiting due to an exclusive acquire. 10976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 10986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the collection of threads 10996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final Collection<Thread> getExclusiveQueuedThreads() { 1101e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak ArrayList<Thread> list = new ArrayList<>(); 11026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node p = tail; p != null; p = p.prev) { 11036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!p.isShared()) { 11046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread t = p.thread; 11056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t != null) 11066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson list.add(t); 11076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return list; 11106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 11136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a collection containing threads that may be waiting to 11146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * acquire in shared mode. This has the same properties 11156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * as {@link #getQueuedThreads} except that it only returns 11166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * those threads waiting due to a shared acquire. 11176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 11186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the collection of threads 11196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final Collection<Thread> getSharedQueuedThreads() { 1121e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak ArrayList<Thread> list = new ArrayList<>(); 11226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node p = tail; p != null; p = p.prev) { 11236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (p.isShared()) { 11246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread t = p.thread; 11256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t != null) 11266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson list.add(t); 11276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return list; 11306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 11336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a string identifying this synchronizer, as well as its state. 11346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * The state, in brackets, includes the String {@code "State ="} 11356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * followed by the current value of {@link #getState}, and either 11366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * {@code "nonempty"} or {@code "empty"} depending on whether the 11376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * queue is empty. 11386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 11396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return a string identifying this synchronizer, as well as its state 11406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public String toString() { 1142e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak return super.toString() 1143e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak + "[State = " + getState() + ", " 1144e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak + (hasQueuedThreads() ? "non" : "") + "empty queue]"; 11456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Internal support methods for Conditions 11496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 11516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if a node, always one that was initially placed on 11526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * a condition queue, is now waiting to reacquire on sync queue. 11536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 11546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return true if is reacquiring 11556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean isOnSyncQueue(Node node) { 11576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.waitStatus == Node.CONDITION || node.prev == null) 11586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 11596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.next != null) // If has successor, it must be on queue 11606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 11616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 11626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * node.prev can be non-null, but not yet on queue because 11636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * the CAS to place it on queue can fail. So we have to 11646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * traverse from tail to make sure it actually made it. It 11656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * will always be near the tail in calls to this method, and 11666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * unless the CAS failed (which is unlikely), it will be 11676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * there, so we hardly ever traverse much. 11686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return findNodeFromTail(node); 11706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 11736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if node is on sync queue by searching backwards from tail. 11746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Called only when needed by isOnSyncQueue. 11756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return true if present 11766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private boolean findNodeFromTail(Node node) { 1178e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // We check for node first, since it's likely to be at or near tail. 1179e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // tail is known to be non-null, so we could re-order to "save" 1180e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // one null check, but we leave it this way to help the VM. 1181e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak for (Node p = tail;;) { 1182aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath if (p == node) 11836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 1184aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath if (p == null) 11856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 1186aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath p = p.prev; 11876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 11896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 11906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 11916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Transfers a node from a condition queue onto sync queue. 11926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if successful. 11936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the node 11946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return true if successfully transferred (else the node was 119591770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * cancelled before signal) 11966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 11976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean transferForSignal(Node node) { 11986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 11996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * If cannot change waitStatus, the node has been cancelled. 12006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1201e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (!node.compareAndSetWaitStatus(Node.CONDITION, 0)) 12026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 12036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 12056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Splice onto queue and try to set waitStatus of predecessor to 12066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * indicate that thread is (probably) waiting. If cancelled or 12076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * attempt to set waitStatus fails, wake up to resync (in which 12086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * case the waitStatus can be transiently and harmlessly wrong). 12096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node p = enq(node); 12116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int ws = p.waitStatus; 1212e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (ws > 0 || !p.compareAndSetWaitStatus(ws, Node.SIGNAL)) 12136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.unpark(node.thread); 12146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 12156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 121891770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Transfers node, if necessary, to sync queue after a cancelled wait. 121991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Returns true if thread was cancelled before being signalled. 122091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * 122191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * @param node the node 12226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return true if cancelled before the node was signalled 12236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean transferAfterCancelledWait(Node node) { 1225e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (node.compareAndSetWaitStatus(Node.CONDITION, 0)) { 12266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson enq(node); 12276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 12286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 12306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * If we lost out to a signal(), then we can't proceed 12316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * until it finishes its enq(). Cancelling during an 12326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * incomplete transfer is both rare and transient, so just 12336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * spin. 12346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) 12366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread.yield(); 12376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 12386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 12416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Invokes release with current state value; returns saved state. 12426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Cancels node and throws exception on failure. 12436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param node the condition node for this wait 12446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return previous sync state 12456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final long fullyRelease(Node node) { 12476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 12486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = getState(); 1249e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (release(savedState)) 12506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return savedState; 1251e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw new IllegalMonitorStateException(); 1252e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (Throwable t) { 1253e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak node.waitStatus = Node.CANCELLED; 1254e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw t; 12556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Instrumentation methods for conditions 12596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 12616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether the given ConditionObject 12626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * uses this synchronizer as its lock. 12636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 12646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param condition the condition 126591770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * @return {@code true} if owned 12666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws NullPointerException if the condition is null 12676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean owns(ConditionObject condition) { 12696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return condition.isOwnedBy(this); 12706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 12736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether any threads are waiting on the given condition 12746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * associated with this synchronizer. Note that because timeouts 127591770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * and interrupts may occur at any time, a {@code true} return 127691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * does not guarantee that a future {@code signal} will awaken 12776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * any threads. This method is designed primarily for use in 12786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * monitoring of the system state. 12796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 12806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param condition the condition 128191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * @return {@code true} if there are any waiting threads 12826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if exclusive synchronization 12836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is not held 12846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalArgumentException if the given condition is 12856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * not associated with this synchronizer 12866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws NullPointerException if the condition is null 12876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 12886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final boolean hasWaiters(ConditionObject condition) { 12896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!owns(condition)) 12906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalArgumentException("Not owner"); 12916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return condition.hasWaiters(); 12926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 12936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 12946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 12956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns an estimate of the number of threads waiting on the 12966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * given condition associated with this synchronizer. Note that 12976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * because timeouts and interrupts may occur at any time, the 12986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * estimate serves only as an upper bound on the actual number of 1299e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * waiters. This method is designed for use in monitoring system 1300e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * state, not for synchronization control. 13016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 13026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param condition the condition 13036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the estimated number of waiting threads 13046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if exclusive synchronization 13056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is not held 13066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalArgumentException if the given condition is 13076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * not associated with this synchronizer 13086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws NullPointerException if the condition is null 13096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final int getWaitQueueLength(ConditionObject condition) { 13116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!owns(condition)) 13126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalArgumentException("Not owner"); 13136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return condition.getWaitQueueLength(); 13146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 13156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 13176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a collection containing those threads that may be 13186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * waiting on the given condition associated with this 13196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronizer. Because the actual set of threads may change 13206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * dynamically while constructing this result, the returned 13216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * collection is only a best-effort estimate. The elements of the 13226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returned collection are in no particular order. 13236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 13246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param condition the condition 13256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the collection of threads 13266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if exclusive synchronization 13276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * is not held 13286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalArgumentException if the given condition is 13296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * not associated with this synchronizer 13306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws NullPointerException if the condition is null 13316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final Collection<Thread> getWaitingThreads(ConditionObject condition) { 13336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!owns(condition)) 13346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalArgumentException("Not owner"); 13356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return condition.getWaitingThreads(); 13366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 13376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 13396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Condition implementation for a {@link 13406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * AbstractQueuedLongSynchronizer} serving as the basis of a {@link 13416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Lock} implementation. 13426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 13436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>Method documentation for this class describes mechanics, 13446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * not behavioral specifications from the point of view of Lock 13456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * and Condition users. Exported versions of this class will in 13466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * general need to be accompanied by documentation describing 13476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * condition semantics that rely on those of the associated 134891770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code AbstractQueuedLongSynchronizer}. 13496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 13506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <p>This class is Serializable, but all fields are transient, 13516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * so deserialized conditions have no waiters. 13526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 13536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @since 1.6 13546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public class ConditionObject implements Condition, java.io.Serializable { 13566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private static final long serialVersionUID = 1173984872572414699L; 13576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** First node of condition queue. */ 13586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private transient Node firstWaiter; 13596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** Last node of condition queue. */ 13606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private transient Node lastWaiter; 13616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 136391770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Creates a new {@code ConditionObject} instance. 13646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public ConditionObject() { } 13666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // Internal methods 13686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 13706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Adds a new waiter to wait queue. 13716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return its new wait node 13726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private Node addConditionWaiter() { 13746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node t = lastWaiter; 13756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // If lastWaiter is cancelled, clean out. 13766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t != null && t.waitStatus != Node.CONDITION) { 13776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unlinkCancelledWaiters(); 13786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson t = lastWaiter; 13796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1380e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak 1381e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Node node = new Node(Node.CONDITION); 1382e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak 13836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t == null) 13846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson firstWaiter = node; 13856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson else 13866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson t.nextWaiter = node; 13876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson lastWaiter = node; 13886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return node; 13896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 13906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 13916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 13926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Removes and transfers nodes until hit non-cancelled one or 13936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * null. Split out from signal in part to encourage compilers 13946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * to inline the case of no waiters. 13956232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param first (non-null) the first node on condition queue 13966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 13976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doSignal(Node first) { 13986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson do { 13996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if ( (firstWaiter = first.nextWaiter) == null) 14006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson lastWaiter = null; 14016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson first.nextWaiter = null; 14026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } while (!transferForSignal(first) && 14036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (first = firstWaiter) != null); 14046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 14076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Removes and transfers all nodes. 14086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @param first (non-null) the first node on condition queue 14096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 14106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void doSignalAll(Node first) { 14116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson lastWaiter = firstWaiter = null; 14126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson do { 14136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node next = first.nextWaiter; 14146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson first.nextWaiter = null; 14156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson transferForSignal(first); 14166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson first = next; 14176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } while (first != null); 14186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 14216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Unlinks cancelled waiter nodes from condition queue. 14226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Called only while holding lock. This is called when 14236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * cancellation occurred during condition wait, and upon 14246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * insertion of a new waiter when lastWaiter is seen to have 14256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * been cancelled. This method is needed to avoid garbage 14266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * retention in the absence of signals. So even though it may 14276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * require a full traversal, it comes into play only when 14286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * timeouts or cancellations occur in the absence of 14296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * signals. It traverses all nodes rather than stopping at a 14306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * particular target to unlink all pointers to garbage nodes 14316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * without requiring many re-traversals during cancellation 14326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * storms. 14336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 14346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void unlinkCancelledWaiters() { 14356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node t = firstWaiter; 14366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node trail = null; 14376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (t != null) { 14386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node next = t.nextWaiter; 14396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t.waitStatus != Node.CONDITION) { 14406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson t.nextWaiter = null; 14416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (trail == null) 14426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson firstWaiter = next; 14436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson else 14446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson trail.nextWaiter = next; 14456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (next == null) 14466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson lastWaiter = trail; 14476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson else 14496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson trail = t; 14506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson t = next; 14516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // public methods 14556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 14576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Moves the longest-waiting thread, if one exists, from the 14586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * wait queue for this condition to the wait queue for the 14596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * owning lock. 14606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 14616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if {@link #isHeldExclusively} 14626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returns {@code false} 14636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 14646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void signal() { 14656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!isHeldExclusively()) 14666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalMonitorStateException(); 14676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node first = firstWaiter; 14686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (first != null) 14696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doSignal(first); 14706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 14736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Moves all threads from the wait queue for this condition to 14746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * the wait queue for the owning lock. 14756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 14766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if {@link #isHeldExclusively} 14776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returns {@code false} 14786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 14796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void signalAll() { 14806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!isHeldExclusively()) 14816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalMonitorStateException(); 14826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node first = firstWaiter; 14836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (first != null) 14846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson doSignalAll(first); 14856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 14866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 14876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 14886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implements uninterruptible condition wait. 14896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <ol> 1490e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Save lock state returned by {@link #getState}. 1491e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Invoke {@link #release} with saved state as argument, 1492e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * throwing IllegalMonitorStateException if it fails. 1493e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Block until signalled. 1494e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Reacquire by invoking specialized version of 1495e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * {@link #acquire} with saved state as argument. 14966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * </ol> 14976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 14986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void awaitUninterruptibly() { 14996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node node = addConditionWaiter(); 15006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = fullyRelease(node); 15016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean interrupted = false; 15026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) { 15036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.park(this); 15046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 15056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interrupted = true; 15066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (acquireQueued(node, savedState) || interrupted) 15086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson selfInterrupt(); 15096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /* 15126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * For interruptible waits, we need to track whether to throw 15136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * InterruptedException, if interrupted while blocked on 15146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * condition, versus reinterrupt current thread, if 15156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * interrupted while blocked waiting to re-acquire. 15166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 15176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** Mode meaning to reinterrupt on exit from wait */ 15196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private static final int REINTERRUPT = 1; 15206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** Mode meaning to throw InterruptedException on exit from wait */ 15216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private static final int THROW_IE = -1; 15226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 15246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Checks for interrupt, returning THROW_IE if interrupted 15256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * before signalled, REINTERRUPT if after signalled, or 15266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 0 if not interrupted. 15276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 15286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private int checkInterruptWhileWaiting(Node node) { 15296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return Thread.interrupted() ? 15306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (transferAfterCancelledWait(node) ? THROW_IE : REINTERRUPT) : 15316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 0; 15326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 15356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Throws InterruptedException, reinterrupts current thread, or 15366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * does nothing, depending on mode. 15376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 15386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private void reportInterruptAfterWait(int interruptMode) 15396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throws InterruptedException { 15406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interruptMode == THROW_IE) 15416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 15426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson else if (interruptMode == REINTERRUPT) 15436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson selfInterrupt(); 15446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 15476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implements interruptible condition wait. 15486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <ol> 1549e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If current thread is interrupted, throw InterruptedException. 1550e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Save lock state returned by {@link #getState}. 1551e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Invoke {@link #release} with saved state as argument, 1552e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * throwing IllegalMonitorStateException if it fails. 1553e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Block until signalled or interrupted. 1554e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Reacquire by invoking specialized version of 1555e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * {@link #acquire} with saved state as argument. 1556e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If interrupted while blocked in step 4, throw InterruptedException. 15576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * </ol> 15586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 15596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson public final void await() throws InterruptedException { 15606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 15616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 15626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node node = addConditionWaiter(); 15636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = fullyRelease(node); 15646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int interruptMode = 0; 15656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) { 15666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.park(this); 15676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if ((interruptMode = checkInterruptWhileWaiting(node)) != 0) 15686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 15696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (acquireQueued(node, savedState) && interruptMode != THROW_IE) 15716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interruptMode = REINTERRUPT; 15726232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.nextWaiter != null) // clean up if cancelled 15736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unlinkCancelledWaiters(); 15746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interruptMode != 0) 15756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson reportInterruptAfterWait(interruptMode); 15766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 15776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 15786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 15796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implements timed condition wait. 15806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <ol> 1581e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If current thread is interrupted, throw InterruptedException. 1582e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Save lock state returned by {@link #getState}. 1583e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Invoke {@link #release} with saved state as argument, 1584e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * throwing IllegalMonitorStateException if it fails. 1585e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Block until signalled, interrupted, or timed out. 1586e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Reacquire by invoking specialized version of 1587e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * {@link #acquire} with saved state as argument. 1588e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If interrupted while blocked in step 4, throw InterruptedException. 15896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * </ol> 15906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 15918eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final long awaitNanos(long nanosTimeout) 15928eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 15936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 15946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 1595e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // We don't check for nanosTimeout <= 0L here, to allow 1596e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // awaitNanos(0) as a way to "yield the lock". 1597e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak final long deadline = System.nanoTime() + nanosTimeout; 1598aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath long initialNanos = nanosTimeout; 15996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node node = addConditionWaiter(); 16006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = fullyRelease(node); 16016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int interruptMode = 0; 16026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) { 16036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (nanosTimeout <= 0L) { 16046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson transferAfterCancelledWait(node); 16056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 16066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1607e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (nanosTimeout > SPIN_FOR_TIMEOUT_THRESHOLD) 160891770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle LockSupport.parkNanos(this, nanosTimeout); 16096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if ((interruptMode = checkInterruptWhileWaiting(node)) != 0) 16106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 161191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle nanosTimeout = deadline - System.nanoTime(); 16126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 16136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (acquireQueued(node, savedState) && interruptMode != THROW_IE) 16146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interruptMode = REINTERRUPT; 16156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.nextWaiter != null) 16166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unlinkCancelledWaiters(); 16176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interruptMode != 0) 16186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson reportInterruptAfterWait(interruptMode); 1619aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath long remaining = deadline - System.nanoTime(); // avoid overflow 16208fc2ac0fa8eb47ce607f8412e469d4f680b6ef85Neil Fuller return (remaining <= initialNanos) ? remaining : Long.MIN_VALUE; 16216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 16226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 16236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 16246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implements absolute timed condition wait. 16256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <ol> 1626e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If current thread is interrupted, throw InterruptedException. 1627e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Save lock state returned by {@link #getState}. 1628e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Invoke {@link #release} with saved state as argument, 1629e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * throwing IllegalMonitorStateException if it fails. 1630e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Block until signalled, interrupted, or timed out. 1631e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Reacquire by invoking specialized version of 1632e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * {@link #acquire} with saved state as argument. 1633e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If interrupted while blocked in step 4, throw InterruptedException. 1634e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If timed out while blocked in step 4, return false, else true. 16356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * </ol> 16366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 16378eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final boolean awaitUntil(Date deadline) 16388eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 16396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long abstime = deadline.getTime(); 16406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 16416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 16426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node node = addConditionWaiter(); 16436232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = fullyRelease(node); 16446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean timedout = false; 16456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int interruptMode = 0; 16466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) { 1647e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (System.currentTimeMillis() >= abstime) { 16486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson timedout = transferAfterCancelledWait(node); 16496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 16506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 16516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.parkUntil(this, abstime); 16526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if ((interruptMode = checkInterruptWhileWaiting(node)) != 0) 16536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 16546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 16556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (acquireQueued(node, savedState) && interruptMode != THROW_IE) 16566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interruptMode = REINTERRUPT; 16576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.nextWaiter != null) 16586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unlinkCancelledWaiters(); 16596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interruptMode != 0) 16606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson reportInterruptAfterWait(interruptMode); 16616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return !timedout; 16626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 16636232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 16646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 16656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Implements timed condition wait. 16666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * <ol> 1667e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If current thread is interrupted, throw InterruptedException. 1668e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Save lock state returned by {@link #getState}. 1669e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Invoke {@link #release} with saved state as argument, 1670e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * throwing IllegalMonitorStateException if it fails. 1671e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Block until signalled, interrupted, or timed out. 1672e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>Reacquire by invoking specialized version of 1673e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * {@link #acquire} with saved state as argument. 1674e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If interrupted while blocked in step 4, throw InterruptedException. 1675e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * <li>If timed out while blocked in step 4, return false, else true. 16766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * </ol> 16776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 16788eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson public final boolean await(long time, TimeUnit unit) 16798eb35c835be1345d3873a82cc9e42f944d698afdJesse Wilson throws InterruptedException { 16806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long nanosTimeout = unit.toNanos(time); 16816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (Thread.interrupted()) 16826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new InterruptedException(); 1683e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // We don't check for nanosTimeout <= 0L here, to allow 1684e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak // await(0, unit) as a way to "yield the lock". 1685e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak final long deadline = System.nanoTime() + nanosTimeout; 16866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Node node = addConditionWaiter(); 16876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson long savedState = fullyRelease(node); 16886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson boolean timedout = false; 16896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int interruptMode = 0; 16906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson while (!isOnSyncQueue(node)) { 16916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (nanosTimeout <= 0L) { 16926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson timedout = transferAfterCancelledWait(node); 16936232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 16946232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 1695e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (nanosTimeout > SPIN_FOR_TIMEOUT_THRESHOLD) 16966232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson LockSupport.parkNanos(this, nanosTimeout); 16976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if ((interruptMode = checkInterruptWhileWaiting(node)) != 0) 16986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson break; 169991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle nanosTimeout = deadline - System.nanoTime(); 17006232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (acquireQueued(node, savedState) && interruptMode != THROW_IE) 17026232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson interruptMode = REINTERRUPT; 17036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (node.nextWaiter != null) 17046232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson unlinkCancelledWaiters(); 17056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (interruptMode != 0) 17066232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson reportInterruptAfterWait(interruptMode); 17076232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return !timedout; 17086232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17096232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17106232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson // support for instrumentation 17116232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17126232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 17136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns true if this condition was created by the given 17146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * synchronization object. 17156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 17166232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if owned 17176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 17186232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson final boolean isOwnedBy(AbstractQueuedLongSynchronizer sync) { 17196232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return sync == AbstractQueuedLongSynchronizer.this; 17206232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17216232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 17236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Queries whether any threads are waiting on this condition. 1724e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Implements {@link AbstractQueuedLongSynchronizer#hasWaiters(ConditionObject)}. 17256232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 17266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return {@code true} if there are any waiting threads 17276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if {@link #isHeldExclusively} 17286232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returns {@code false} 17296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 17306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final boolean hasWaiters() { 17316232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!isHeldExclusively()) 17326232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalMonitorStateException(); 17336232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node w = firstWaiter; w != null; w = w.nextWaiter) { 17346232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (w.waitStatus == Node.CONDITION) 17356232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return true; 17366232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17376232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return false; 17386232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17396232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17406232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 17416232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns an estimate of the number of threads waiting on 17426232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * this condition. 1743e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Implements {@link AbstractQueuedLongSynchronizer#getWaitQueueLength(ConditionObject)}. 17446232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 17456232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the estimated number of waiting threads 17466232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if {@link #isHeldExclusively} 17476232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returns {@code false} 17486232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 17496232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final int getWaitQueueLength() { 17506232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!isHeldExclusively()) 17516232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalMonitorStateException(); 17526232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson int n = 0; 17536232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node w = firstWaiter; w != null; w = w.nextWaiter) { 17546232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (w.waitStatus == Node.CONDITION) 17556232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson ++n; 17566232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17576232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return n; 17586232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17596232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17606232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 17616232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Returns a collection containing those threads that may be 17626232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * waiting on this Condition. 1763e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Implements {@link AbstractQueuedLongSynchronizer#getWaitingThreads(ConditionObject)}. 17646232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * 17656232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @return the collection of threads 17666232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * @throws IllegalMonitorStateException if {@link #isHeldExclusively} 17676232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * returns {@code false} 17686232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 17696232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson protected final Collection<Thread> getWaitingThreads() { 17706232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (!isHeldExclusively()) 17716232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson throw new IllegalMonitorStateException(); 1772e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak ArrayList<Thread> list = new ArrayList<>(); 17736232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson for (Node w = firstWaiter; w != null; w = w.nextWaiter) { 17746232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (w.waitStatus == Node.CONDITION) { 17756232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson Thread t = w.thread; 17766232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson if (t != null) 17776232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson list.add(t); 17786232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17796232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17806232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson return list; 17816232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17826232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 17836232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17846232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 17856232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * Setup to support compareAndSet. We need to natively implement 17866232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * this here: For the sake of permitting future enhancements, we 17876232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * cannot explicitly subclass AtomicLong, which would be 17886232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * efficient and useful otherwise. So, as the lesser of evils, we 17896232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * natively implement using hotspot intrinsics API. And while we 17906232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * are at it, we do the same for other CASable fields (which could 17916232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson * otherwise be done with atomic field updaters). 17926232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1793e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe(); 1794e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private static final long STATE; 1795e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private static final long HEAD; 1796e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private static final long TAIL; 17976232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 17986232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson static { 17996232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson try { 1800e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak STATE = U.objectFieldOffset 18016232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (AbstractQueuedLongSynchronizer.class.getDeclaredField("state")); 1802e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak HEAD = U.objectFieldOffset 18036232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (AbstractQueuedLongSynchronizer.class.getDeclaredField("head")); 1804e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak TAIL = U.objectFieldOffset 18056232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson (AbstractQueuedLongSynchronizer.class.getDeclaredField("tail")); 1806e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } catch (ReflectiveOperationException e) { 1807e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak throw new Error(e); 1808e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak } 1809aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath 1810aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath // Reduce the risk of rare disastrous classloading in first call to 1811aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773 1812aa2ed9e105504f21641d919b410c692981cfe386Narayan Kamath Class<?> ensureLoaded = LockSupport.class; 18136232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 18146232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 18156232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1816e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * Initializes head and tail fields on first contention. 18176232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 1818e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak private final void initializeSyncQueue() { 1819e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak Node h; 1820e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak if (U.compareAndSwapObject(this, HEAD, null, (h = new Node()))) 1821e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak tail = h; 18226232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 18236232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson 18246232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson /** 1825e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak * CASes tail field. 18266232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson */ 18276232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson private final boolean compareAndSetTail(Node expect, Node update) { 1828e8b323c7cb7d55be9a4df579231e44f04f53d766Przemyslaw Szczepaniak return U.compareAndSwapObject(this, TAIL, expect, update); 18296232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson } 18306232a5efed0ea103e35aec73206e5e03a8b82e0cJesse Wilson} 1831