151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/* 246805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. 351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is free software; you can redistribute it and/or modify it 651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * under the terms of the GNU General Public License version 2 only, as 751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * published by the Free Software Foundation. Oracle designates this 851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * particular file as subject to the "Classpath" exception as provided 951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by Oracle in the LICENSE file that accompanied this code. 1051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This code is distributed in the hope that it will be useful, but WITHOUT 1251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * version 2 for more details (a copy is included in the LICENSE file that 1551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * accompanied this code). 1651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 1751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * You should have received a copy of the GNU General Public License version 1851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2 along with this work; if not, write to the Free Software Foundation, 1951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 2051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 2151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * or visit www.oracle.com if you need additional information or have any 2351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * questions. 2451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 2551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipackage java.nio.channels; 2751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 2851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.io.Closeable; 2951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.io.IOException; 3051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.nio.channels.spi.SelectorProvider; 3151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskiimport java.util.Set; 3251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 3351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 3451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski/** 3551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * A multiplexor of {@link SelectableChannel} objects. 3651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 3751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A selector may be created by invoking the {@link #open open} method of 3851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * this class, which will use the system's default {@link 3946805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * java.nio.channels.spi.SelectorProvider selector provider} to 4051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * create a new selector. A selector may also be created by invoking the 4151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link java.nio.channels.spi.SelectorProvider#openSelector openSelector} 4251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method of a custom selector provider. A selector remains open until it is 4351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * closed via its {@link #close close} method. 4451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4546805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <a name="ks"></a> 4651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 4751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A selectable channel's registration with a selector is represented by a 4851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link SelectionKey} object. A selector maintains three sets of selection 4951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * keys: 5051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <ul> 5251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> The <i>key set</i> contains the keys representing the current 5451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * channel registrations of this selector. This set is returned by the 5551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link #keys() keys} method. </p></li> 5651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 5751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> The <i>selected-key set</i> is the set of keys such that each 5851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * key's channel was detected to be ready for at least one of the operations 5951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * identified in the key's interest set during a prior selection operation. 6051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * This set is returned by the {@link #selectedKeys() selectedKeys} method. 6151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * The selected-key set is always a subset of the key set. </p></li> 6251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> The <i>cancelled-key</i> set is the set of keys that have been 6451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled but whose channels have not yet been deregistered. This set is 6551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * not directly accessible. The cancelled-key set is always a subset of the 6651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * key set. </p></li> 6751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 6851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </ul> 6951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> All three sets are empty in a newly-created selector. 7151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A key is added to a selector's key set as a side effect of registering a 7351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * channel via the channel's {@link SelectableChannel#register(Selector,int) 7451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * register} method. Cancelled keys are removed from the key set during 7551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * selection operations. The key set itself is not directly modifiable. 7651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 7751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A key is added to its selector's cancelled-key set when it is cancelled, 7851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whether by closing its channel or by invoking its {@link SelectionKey#cancel 7951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancel} method. Cancelling a key will cause its channel to be deregistered 8051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * during the next selection operation, at which time the key will removed from 8151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * all of the selector's key sets. 8251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 8346805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <a name="sks"></a><p> Keys are added to the selected-key set by selection 8451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations. A key may be removed directly from the selected-key set by 8551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * invoking the set's {@link java.util.Set#remove(java.lang.Object) remove} 8651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method or by invoking the {@link java.util.Iterator#remove() remove} method 8746805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * of an {@link java.util.Iterator iterator} obtained from the 8851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * set. Keys are never removed from the selected-key set in any other way; 8951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * they are not, in particular, removed as a side effect of selection 9051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations. Keys may not be added directly to the selected-key set. </p> 9151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 9251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 9346805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <a name="selop"></a> 9446805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <h2>Selection</h2> 9551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 9651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> During each selection operation, keys may be added to and removed from a 9751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * selector's selected-key set and may be removed from its key and 9851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cancelled-key sets. Selection is performed by the {@link #select()}, {@link 9951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * #select(long)}, and {@link #selectNow()} methods, and involves three steps: 10051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </p> 10151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 10251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <ol> 10351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 10451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> Each key in the cancelled-key set is removed from each key set of 10551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * which it is a member, and its channel is deregistered. This step leaves 10651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the cancelled-key set empty. </p></li> 10751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 10851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> The underlying operating system is queried for an update as to the 10951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * readiness of each remaining channel to perform any of the operations 11051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * identified by its key's interest set as of the moment that the selection 11151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation began. For a channel that is ready for at least one such 11251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation, one of the following two actions is performed: </p> 11351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 11446805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <ol> 11551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 11651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> If the channel's key is not already in the selected-key set then 11751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * it is added to that set and its ready-operation set is modified to 11851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * identify exactly those operations for which the channel is now reported 11951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * to be ready. Any readiness information previously recorded in the ready 12051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * set is discarded. </p></li> 12151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 12251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> Otherwise the channel's key is already in the selected-key set, 12351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * so its ready-operation set is modified to identify any new operations 12451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * for which the channel is reported to be ready. Any readiness 12551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * information previously recorded in the ready set is preserved; in other 12651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * words, the ready set returned by the underlying system is 12751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * bitwise-disjoined into the key's current ready set. </p></li> 12851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 12946805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * </ol> 13051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 13151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If all of the keys in the key set at the start of this step have empty 13251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * interest sets then neither the selected-key set nor any of the keys' 13351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * ready-operation sets will be updated. 13451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 13551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> If any keys were added to the cancelled-key set while step (2) was 13651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * in progress then they are processed as in step (1). </p></li> 13751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 13851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </ol> 13951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Whether or not a selection operation blocks to wait for one or more 14151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * channels to become ready, and if so for how long, is the only essential 14251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * difference between the three selection methods. </p> 14351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14546805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <h2>Concurrency</h2> 14651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 14751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Selectors are themselves safe for use by multiple concurrent threads; 14851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * their key sets, however, are not. 14951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 15051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The selection operations synchronize on the selector itself, on the key 15151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * set, and on the selected-key set, in that order. They also synchronize on 15251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * the cancelled-key set during steps (1) and (3) above. 15351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 15451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Changes made to the interest sets of a selector's keys while a 15551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * selection operation is in progress have no effect upon that operation; they 15651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * will be seen by the next selection operation. 15751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 15851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Keys may be cancelled and channels may be closed at any time. Hence the 15951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * presence of a key in one or more of a selector's key sets does not imply 16051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * that the key is valid or that its channel is open. Application code should 16151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * be careful to synchronize and check these conditions as necessary if there 16251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is any possibility that another thread will cancel a key or close a channel. 16351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 16451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A thread blocked in one of the {@link #select()} or {@link 16551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * #select(long)} methods may be interrupted by some other thread in one of 16651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * three ways: 16751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 16851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <ul> 16951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 17051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> By invoking the selector's {@link #wakeup wakeup} method, 17151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </p></li> 17251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 17351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> By invoking the selector's {@link #close close} method, or 17451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </p></li> 17551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 17651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <li><p> By invoking the blocked thread's {@link 17751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * java.lang.Thread#interrupt() interrupt} method, in which case its 17851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * interrupt status will be set and the selector's {@link #wakeup wakeup} 17951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * method will be invoked. </p></li> 18051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 18151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * </ul> 18251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 18351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The {@link #close close} method synchronizes on the selector and all 18451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * three key sets in the same order as in a selection operation. 18551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 18646805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * <a name="ksc"></a> 18751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 18851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> A selector's key and selected-key sets are not, in general, safe for use 18951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * by multiple concurrent threads. If such a thread might modify one of these 19051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * sets directly then access should be controlled by synchronizing on the set 19151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * itself. The iterators returned by these sets' {@link 19251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * java.util.Set#iterator() iterator} methods are <i>fail-fast:</i> If the set 19351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * is modified after the iterator is created, in any way except by invoking the 19451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * iterator's own {@link java.util.Iterator#remove() remove} method, then a 19551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link java.util.ConcurrentModificationException} will be thrown. </p> 19651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 19751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 19851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author Mark Reinhold 19951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @author JSR-51 Expert Group 20051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @since 1.4 20151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 20251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see SelectableChannel 20351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @see SelectionKey 20451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 20551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 20651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebskipublic abstract class Selector implements Closeable { 20751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 20851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 20951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Initializes a new instance of this class. 21051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 21151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski protected Selector() { } 21251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 21351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 21451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Opens a selector. 21551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 21651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The new selector is created by invoking the {@link 21751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * java.nio.channels.spi.SelectorProvider#openSelector openSelector} method 21851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * of the system-wide default {@link 21951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * java.nio.channels.spi.SelectorProvider} object. </p> 22051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 22151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return A new selector 22251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 22351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 22451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 22551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 22651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public static Selector open() throws IOException { 22751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski return SelectorProvider.provider().openSelector(); 22851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski } 22951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 23051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 23146805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Tells whether or not this selector is open. 23251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 23351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return <tt>true</tt> if, and only if, this selector is open 23451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 23551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract boolean isOpen(); 23651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 23751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 23846805d66f32e857c885434b4fa8cb6b32dcc4bf7Shubham Ajmera * Returns the provider that created this channel. 23951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 24051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The provider that created this channel 24151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 24251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract SelectorProvider provider(); 24351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 24451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 24551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns this selector's key set. 24651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 24751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The key set is not directly modifiable. A key is removed only after 24851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * it has been cancelled and its channel has been deregistered. Any 24951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * attempt to modify the key set will cause an {@link 25051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * UnsupportedOperationException} to be thrown. 25151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 25251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The key set is <a href="#ksc">not thread-safe</a>. </p> 25351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 25451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return This selector's key set 25551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 25651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedSelectorException 25751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If this selector is closed 25851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 25951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract Set<SelectionKey> keys(); 26051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 26151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 26251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Returns this selector's selected-key set. 26351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 26451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Keys may be removed from, but not directly added to, the 26551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * selected-key set. Any attempt to add an object to the key set will 26651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * cause an {@link UnsupportedOperationException} to be thrown. 26751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 26851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> The selected-key set is <a href="#ksc">not thread-safe</a>. </p> 26951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 27051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return This selector's selected-key set 27151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 27251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedSelectorException 27351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If this selector is closed 27451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 27551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract Set<SelectionKey> selectedKeys(); 27651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 27751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 27851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Selects a set of keys whose corresponding channels are ready for I/O 27951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations. 28051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 28151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This method performs a non-blocking <a href="#selop">selection 28251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation</a>. If no channels have become selectable since the previous 28351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * selection operation then this method immediately returns zero. 28451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 28551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Invoking this method clears the effect of any previous invocations 28651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * of the {@link #wakeup wakeup} method. </p> 28751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 28851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The number of keys, possibly zero, whose ready-operation sets 28951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * were updated by the selection operation 29051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 29151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 29251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 29351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 29451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedSelectorException 29551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If this selector is closed 29651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 29751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract int selectNow() throws IOException; 29851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 29951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 30051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Selects a set of keys whose corresponding channels are ready for I/O 30151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations. 30251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 30351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This method performs a blocking <a href="#selop">selection 30451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation</a>. It returns only after at least one channel is selected, 30551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * this selector's {@link #wakeup wakeup} method is invoked, the current 30651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * thread is interrupted, or the given timeout period expires, whichever 30751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * comes first. 30851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 30951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This method does not offer real-time guarantees: It schedules the 31051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * timeout as if by invoking the {@link Object#wait(long)} method. </p> 31151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 31251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @param timeout If positive, block for up to <tt>timeout</tt> 31351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * milliseconds, more or less, while waiting for a 31451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * channel to become ready; if zero, block indefinitely; 31551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * must not be negative 31651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 31751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The number of keys, possibly zero, 31851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whose ready-operation sets were updated 31951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 32051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 32151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 32251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 32351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedSelectorException 32451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If this selector is closed 32551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 32651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IllegalArgumentException 32751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If the value of the timeout argument is negative 32851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 32951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract int select(long timeout) 33051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski throws IOException; 33151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 33251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 33351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Selects a set of keys whose corresponding channels are ready for I/O 33451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations. 33551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 33651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> This method performs a blocking <a href="#selop">selection 33751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operation</a>. It returns only after at least one channel is selected, 33851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * this selector's {@link #wakeup wakeup} method is invoked, or the current 33951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * thread is interrupted, whichever comes first. </p> 34051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 34151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return The number of keys, possibly zero, 34251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * whose ready-operation sets were updated 34351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 34451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 34551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 34651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 34751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws ClosedSelectorException 34851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If this selector is closed 34951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 35051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract int select() throws IOException; 35151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 35251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 35351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Causes the first selection operation that has not yet returned to return 35451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * immediately. 35551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 35651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> If another thread is currently blocked in an invocation of the 35751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link #select()} or {@link #select(long)} methods then that invocation 35851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * will return immediately. If no selection operation is currently in 35951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * progress then the next invocation of one of these methods will return 36051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * immediately unless the {@link #selectNow()} method is invoked in the 36151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * meantime. In any case the value returned by that invocation may be 36251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * non-zero. Subsequent invocations of the {@link #select()} or {@link 36351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * #select(long)} methods will block as usual unless this method is invoked 36451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * again in the meantime. 36551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 36651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Invoking this method more than once between two successive selection 36751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * operations has the same effect as invoking it just once. </p> 36851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 36951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @return This selector 37051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 37151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract Selector wakeup(); 37251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 37351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski /** 37451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * Closes this selector. 37551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 37651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> If a thread is currently blocked in one of this selector's selection 37751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * methods then it is interrupted as if by invoking the selector's {@link 37851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * #wakeup wakeup} method. 37951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 38051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> Any uncancelled keys still associated with this selector are 38151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * invalidated, their channels are deregistered, and any other resources 38251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * associated with this selector are released. 38351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 38451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> If this selector is already closed then invoking this method has no 38551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * effect. 38651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 38751b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * <p> After a selector is closed, any further attempt to use it, except by 38851b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * invoking this method or the {@link #wakeup wakeup} method, will cause a 38951b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * {@link ClosedSelectorException} to be thrown. </p> 39051b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * 39151b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * @throws IOException 39251b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski * If an I/O error occurs 39351b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski */ 39451b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski public abstract void close() throws IOException; 39551b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski 39651b1b6997fd3f980076b8081f7f1165ccc2a4008Piotr Jastrzebski} 397