mutex.h revision eac4424b3420c280f97ff2f815b5dedd8dac9801
1/* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef ART_RUNTIME_BASE_MUTEX_H_ 18#define ART_RUNTIME_BASE_MUTEX_H_ 19 20#include <pthread.h> 21#include <stdint.h> 22 23#include <iosfwd> 24#include <string> 25 26#include "atomic.h" 27#include "base/logging.h" 28#include "base/macros.h" 29#include "globals.h" 30 31#if defined(__APPLE__) 32#define ART_USE_FUTEXES 0 33#else 34#define ART_USE_FUTEXES 1 35#endif 36 37// Currently Darwin doesn't support locks with timeouts. 38#if !defined(__APPLE__) 39#define HAVE_TIMED_RWLOCK 1 40#else 41#define HAVE_TIMED_RWLOCK 0 42#endif 43 44namespace art { 45 46class LOCKABLE ReaderWriterMutex; 47class LOCKABLE MutatorMutex; 48class ScopedContentionRecorder; 49class Thread; 50 51// LockLevel is used to impose a lock hierarchy [1] where acquisition of a Mutex at a higher or 52// equal level to a lock a thread holds is invalid. The lock hierarchy achieves a cycle free 53// partial ordering and thereby cause deadlock situations to fail checks. 54// 55// [1] http://www.drdobbs.com/parallel/use-lock-hierarchies-to-avoid-deadlock/204801163 56enum LockLevel { 57 kLoggingLock = 0, 58 kMemMapsLock, 59 kSwapMutexesLock, 60 kUnexpectedSignalLock, 61 kThreadSuspendCountLock, 62 kAbortLock, 63 kJdwpSocketLock, 64 kRegionSpaceRegionLock, 65 kTransactionLogLock, 66 kReferenceQueueSoftReferencesLock, 67 kReferenceQueuePhantomReferencesLock, 68 kReferenceQueueFinalizerReferencesLock, 69 kReferenceQueueWeakReferencesLock, 70 kReferenceQueueClearedReferencesLock, 71 kReferenceProcessorLock, 72 kJitCodeCacheLock, 73 kRosAllocGlobalLock, 74 kRosAllocBracketLock, 75 kRosAllocBulkFreeLock, 76 kAllocSpaceLock, 77 kBumpPointerSpaceBlockLock, 78 kArenaPoolLock, 79 kDexFileMethodInlinerLock, 80 kDexFileToMethodInlinerMapLock, 81 kMarkSweepMarkStackLock, 82 kInternTableLock, 83 kOatFileSecondaryLookupLock, 84 kTracingUniqueMethodsLock, 85 kTracingStreamingLock, 86 kDefaultMutexLevel, 87 kMarkSweepLargeObjectLock, 88 kPinTableLock, 89 kJdwpObjectRegistryLock, 90 kModifyLdtLock, 91 kAllocatedThreadIdsLock, 92 kMonitorPoolLock, 93 kMethodVerifiersLock, 94 kClassLinkerClassesLock, 95 kBreakpointLock, 96 kMonitorLock, 97 kMonitorListLock, 98 kJniLoadLibraryLock, 99 kThreadListLock, 100 kAllocTrackerLock, 101 kDeoptimizationLock, 102 kProfilerLock, 103 kJdwpShutdownLock, 104 kJdwpEventListLock, 105 kJdwpAttachLock, 106 kJdwpStartLock, 107 kRuntimeShutdownLock, 108 kTraceLock, 109 kHeapBitmapLock, 110 kMutatorLock, 111 kInstrumentEntrypointsLock, 112 kZygoteCreationLock, 113 114 kLockLevelCount // Must come last. 115}; 116std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 117 118const bool kDebugLocking = kIsDebugBuild; 119 120// Record Log contention information, dumpable via SIGQUIT. 121#ifdef ART_USE_FUTEXES 122// To enable lock contention logging, set this to true. 123const bool kLogLockContentions = false; 124#else 125// Keep this false as lock contention logging is supported only with 126// futex. 127const bool kLogLockContentions = false; 128#endif 129const size_t kContentionLogSize = 4; 130const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 131const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 132 133// Base class for all Mutex implementations 134class BaseMutex { 135 public: 136 const char* GetName() const { 137 return name_; 138 } 139 140 virtual bool IsMutex() const { return false; } 141 virtual bool IsReaderWriterMutex() const { return false; } 142 virtual bool IsMutatorMutex() const { return false; } 143 144 virtual void Dump(std::ostream& os) const = 0; 145 146 static void DumpAll(std::ostream& os); 147 148 protected: 149 friend class ConditionVariable; 150 151 BaseMutex(const char* name, LockLevel level); 152 virtual ~BaseMutex(); 153 void RegisterAsLocked(Thread* self); 154 void RegisterAsUnlocked(Thread* self); 155 void CheckSafeToWait(Thread* self); 156 157 friend class ScopedContentionRecorder; 158 159 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 160 void DumpContention(std::ostream& os) const; 161 162 const LockLevel level_; // Support for lock hierarchy. 163 const char* const name_; 164 165 // A log entry that records contention but makes no guarantee that either tid will be held live. 166 struct ContentionLogEntry { 167 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 168 uint64_t blocked_tid; 169 uint64_t owner_tid; 170 AtomicInteger count; 171 }; 172 struct ContentionLogData { 173 ContentionLogEntry contention_log[kContentionLogSize]; 174 // The next entry in the contention log to be updated. Value ranges from 0 to 175 // kContentionLogSize - 1. 176 AtomicInteger cur_content_log_entry; 177 // Number of times the Mutex has been contended. 178 AtomicInteger contention_count; 179 // Sum of time waited by all contenders in ns. 180 Atomic<uint64_t> wait_time; 181 void AddToWaitTime(uint64_t value); 182 ContentionLogData() : wait_time(0) {} 183 }; 184 ContentionLogData contention_log_data_[kContentionLogDataSize]; 185 186 public: 187 bool HasEverContended() const { 188 if (kLogLockContentions) { 189 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 190 } 191 return false; 192 } 193}; 194 195// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 196// exclusive access to what it guards. A Mutex can be in one of two states: 197// - Free - not owned by any thread, 198// - Exclusive - owned by a single thread. 199// 200// The effect of locking and unlocking operations on the state is: 201// State | ExclusiveLock | ExclusiveUnlock 202// ------------------------------------------- 203// Free | Exclusive | error 204// Exclusive | Block* | Free 205// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 206// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 207std::ostream& operator<<(std::ostream& os, const Mutex& mu); 208class LOCKABLE Mutex : public BaseMutex { 209 public: 210 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 211 ~Mutex(); 212 213 virtual bool IsMutex() const { return true; } 214 215 // Block until mutex is free then acquire exclusive access. 216 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 217 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 218 219 // Returns true if acquires exclusive access, false otherwise. 220 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 221 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 222 223 // Release exclusive access. 224 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 225 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 226 227 // Is the current thread the exclusive holder of the Mutex. 228 bool IsExclusiveHeld(const Thread* self) const; 229 230 // Assert that the Mutex is exclusively held by the current thread. 231 void AssertExclusiveHeld(const Thread* self) { 232 if (kDebugLocking && (gAborting == 0)) { 233 CHECK(IsExclusiveHeld(self)) << *this; 234 } 235 } 236 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 237 238 // Assert that the Mutex is not held by the current thread. 239 void AssertNotHeldExclusive(const Thread* self) { 240 if (kDebugLocking && (gAborting == 0)) { 241 CHECK(!IsExclusiveHeld(self)) << *this; 242 } 243 } 244 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 245 246 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 247 // than the owner. 248 uint64_t GetExclusiveOwnerTid() const; 249 250 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 251 unsigned int GetDepth() const { 252 return recursion_count_; 253 } 254 255 virtual void Dump(std::ostream& os) const; 256 257 private: 258#if ART_USE_FUTEXES 259 // 0 is unheld, 1 is held. 260 AtomicInteger state_; 261 // Exclusive owner. 262 volatile uint64_t exclusive_owner_; 263 // Number of waiting contenders. 264 AtomicInteger num_contenders_; 265#else 266 pthread_mutex_t mutex_; 267 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 268#endif 269 const bool recursive_; // Can the lock be recursively held? 270 unsigned int recursion_count_; 271 friend class ConditionVariable; 272 DISALLOW_COPY_AND_ASSIGN(Mutex); 273}; 274 275// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 276// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 277// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 278// condition variable. A ReaderWriterMutex can be in one of three states: 279// - Free - not owned by any thread, 280// - Exclusive - owned by a single thread, 281// - Shared(n) - shared amongst n threads. 282// 283// The effect of locking and unlocking operations on the state is: 284// 285// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 286// ---------------------------------------------------------------------------- 287// Free | Exclusive | error | SharedLock(1) | error 288// Exclusive | Block | Free | Block | error 289// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 290// * for large values of n the SharedLock may block. 291std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 292class LOCKABLE ReaderWriterMutex : public BaseMutex { 293 public: 294 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 295 ~ReaderWriterMutex(); 296 297 virtual bool IsReaderWriterMutex() const { return true; } 298 299 // Block until ReaderWriterMutex is free then acquire exclusive access. 300 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 301 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 302 303 // Release exclusive access. 304 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 305 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 306 307 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 308 // or false if timeout is reached. 309#if HAVE_TIMED_RWLOCK 310 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 311 EXCLUSIVE_TRYLOCK_FUNCTION(true); 312#endif 313 314 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 315 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 316 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 317 318 // Try to acquire share of ReaderWriterMutex. 319 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 320 321 // Release a share of the access. 322 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 323 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 324 325 // Is the current thread the exclusive holder of the ReaderWriterMutex. 326 bool IsExclusiveHeld(const Thread* self) const; 327 328 // Assert the current thread has exclusive access to the ReaderWriterMutex. 329 void AssertExclusiveHeld(const Thread* self) { 330 if (kDebugLocking && (gAborting == 0)) { 331 CHECK(IsExclusiveHeld(self)) << *this; 332 } 333 } 334 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 335 336 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 337 void AssertNotExclusiveHeld(const Thread* self) { 338 if (kDebugLocking && (gAborting == 0)) { 339 CHECK(!IsExclusiveHeld(self)) << *this; 340 } 341 } 342 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 343 344 // Is the current thread a shared holder of the ReaderWriterMutex. 345 bool IsSharedHeld(const Thread* self) const; 346 347 // Assert the current thread has shared access to the ReaderWriterMutex. 348 void AssertSharedHeld(const Thread* self) { 349 if (kDebugLocking && (gAborting == 0)) { 350 // TODO: we can only assert this well when self != null. 351 CHECK(IsSharedHeld(self) || self == nullptr) << *this; 352 } 353 } 354 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 355 356 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 357 // mode. 358 void AssertNotHeld(const Thread* self) { 359 if (kDebugLocking && (gAborting == 0)) { 360 CHECK(!IsSharedHeld(self)) << *this; 361 } 362 } 363 364 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 365 // than the owner. 366 uint64_t GetExclusiveOwnerTid() const; 367 368 virtual void Dump(std::ostream& os) const; 369 370 private: 371#if ART_USE_FUTEXES 372 // Out-of-inline path for handling contention for a SharedLock. 373 void HandleSharedLockContention(Thread* self, int32_t cur_state); 374 375 // -1 implies held exclusive, +ve shared held by state_ many owners. 376 AtomicInteger state_; 377 // Exclusive owner. Modification guarded by this mutex. 378 volatile uint64_t exclusive_owner_; 379 // Number of contenders waiting for a reader share. 380 AtomicInteger num_pending_readers_; 381 // Number of contenders waiting to be the writer. 382 AtomicInteger num_pending_writers_; 383#else 384 pthread_rwlock_t rwlock_; 385 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 386#endif 387 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 388}; 389 390// MutatorMutex is a special kind of ReaderWriterMutex created specifically for the 391// Locks::mutator_lock_ mutex. The behaviour is identical to the ReaderWriterMutex except that 392// thread state changes also play a part in lock ownership. The mutator_lock_ will not be truly 393// held by any mutator threads. However, a thread in the kRunnable state is considered to have 394// shared ownership of the mutator lock and therefore transitions in and out of the kRunnable 395// state have associated implications on lock ownership. Extra methods to handle the state 396// transitions have been added to the interface but are only accessible to the methods dealing 397// with state transitions. The thread state and flags attributes are used to ensure thread state 398// transitions are consistent with the permitted behaviour of the mutex. 399// 400// *) The most important consequence of this behaviour is that all threads must be in one of the 401// suspended states before exclusive ownership of the mutator mutex is sought. 402// 403std::ostream& operator<<(std::ostream& os, const MutatorMutex& mu); 404class LOCKABLE MutatorMutex : public ReaderWriterMutex { 405 public: 406 explicit MutatorMutex(const char* name, LockLevel level = kDefaultMutexLevel) 407 : ReaderWriterMutex(name, level) {} 408 ~MutatorMutex() {} 409 410 virtual bool IsMutatorMutex() const { return true; } 411 412 private: 413 friend class Thread; 414 void TransitionFromRunnableToSuspended(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 415 void TransitionFromSuspendedToRunnable(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 416 417 DISALLOW_COPY_AND_ASSIGN(MutatorMutex); 418}; 419 420// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 421// (Signal) or all at once (Broadcast). 422class ConditionVariable { 423 public: 424 explicit ConditionVariable(const char* name, Mutex& mutex); 425 ~ConditionVariable(); 426 427 void Broadcast(Thread* self); 428 void Signal(Thread* self); 429 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 430 // pointer copy, thereby defeating annotalysis. 431 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 432 bool TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 433 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 434 // when waiting. 435 // TODO: remove this. 436 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 437 438 private: 439 const char* const name_; 440 // The Mutex being used by waiters. It is an error to mix condition variables between different 441 // Mutexes. 442 Mutex& guard_; 443#if ART_USE_FUTEXES 444 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 445 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 446 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 447 // without guard_ held. 448 AtomicInteger sequence_; 449 // Number of threads that have come into to wait, not the length of the waiters on the futex as 450 // waiters may have been requeued onto guard_. Guarded by guard_. 451 volatile int32_t num_waiters_; 452#else 453 pthread_cond_t cond_; 454#endif 455 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 456}; 457 458// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 459// upon destruction. 460class SCOPED_LOCKABLE MutexLock { 461 public: 462 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 463 mu_.ExclusiveLock(self_); 464 } 465 466 ~MutexLock() UNLOCK_FUNCTION() { 467 mu_.ExclusiveUnlock(self_); 468 } 469 470 private: 471 Thread* const self_; 472 Mutex& mu_; 473 DISALLOW_COPY_AND_ASSIGN(MutexLock); 474}; 475// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 476#define MutexLock(x) static_assert(0, "MutexLock declaration missing variable name") 477 478// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 479// construction and releases it upon destruction. 480class SCOPED_LOCKABLE ReaderMutexLock { 481 public: 482 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 483 self_(self), mu_(mu) { 484 mu_.SharedLock(self_); 485 } 486 487 ~ReaderMutexLock() UNLOCK_FUNCTION() { 488 mu_.SharedUnlock(self_); 489 } 490 491 private: 492 Thread* const self_; 493 ReaderWriterMutex& mu_; 494 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 495}; 496// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 497// "ReaderMutexLock mu(lock)". 498#define ReaderMutexLock(x) static_assert(0, "ReaderMutexLock declaration missing variable name") 499 500// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 501// construction and releases it upon destruction. 502class SCOPED_LOCKABLE WriterMutexLock { 503 public: 504 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 505 self_(self), mu_(mu) { 506 mu_.ExclusiveLock(self_); 507 } 508 509 ~WriterMutexLock() UNLOCK_FUNCTION() { 510 mu_.ExclusiveUnlock(self_); 511 } 512 513 private: 514 Thread* const self_; 515 ReaderWriterMutex& mu_; 516 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 517}; 518// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 519// "WriterMutexLock mu(lock)". 520#define WriterMutexLock(x) static_assert(0, "WriterMutexLock declaration missing variable name") 521 522// Global mutexes corresponding to the levels above. 523class Locks { 524 public: 525 static void Init(); 526 static void InitConditions() NO_THREAD_SAFETY_ANALYSIS; // Condition variables. 527 // Guards allocation entrypoint instrumenting. 528 static Mutex* instrument_entrypoints_lock_; 529 530 // A barrier is used to synchronize the GC/Debugger thread with mutator threads. When GC/Debugger 531 // thread wants to suspend all mutator threads, it needs to wait for all mutator threads to pass 532 // a barrier. Threads that are already suspended will get their barrier passed by the GC/Debugger 533 // thread; threads in the runnable state will pass the barrier when they transit to the suspended 534 // state. GC/Debugger thread will be woken up when all mutator threads are suspended. 535 // 536 // Thread suspension: 537 // mutator thread | GC/Debugger 538 // .. running .. | .. running .. 539 // .. running .. | Request thread suspension by: 540 // .. running .. | - acquiring thread_suspend_count_lock_ 541 // .. running .. | - incrementing Thread::suspend_count_ on 542 // .. running .. | all mutator threads 543 // .. running .. | - releasing thread_suspend_count_lock_ 544 // .. running .. | Block wait for all threads to pass a barrier 545 // Poll Thread::suspend_count_ and enter full | .. blocked .. 546 // suspend code. | .. blocked .. 547 // Change state to kSuspended (pass the barrier) | Wake up when all threads pass the barrier 548 // x: Acquire thread_suspend_count_lock_ | .. running .. 549 // while Thread::suspend_count_ > 0 | .. running .. 550 // - wait on Thread::resume_cond_ | .. running .. 551 // (releases thread_suspend_count_lock_) | .. running .. 552 // .. waiting .. | Request thread resumption by: 553 // .. waiting .. | - acquiring thread_suspend_count_lock_ 554 // .. waiting .. | - decrementing Thread::suspend_count_ on 555 // .. waiting .. | all mutator threads 556 // .. waiting .. | - notifying on Thread::resume_cond_ 557 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 558 // Release thread_suspend_count_lock_ | .. running .. 559 // Change to kRunnable | .. running .. 560 // - this uses a CAS operation to ensure the | .. running .. 561 // suspend request flag isn't raised as the | .. running .. 562 // state is changed | .. running .. 563 // - if the CAS operation fails then goto x | .. running .. 564 // .. running .. | .. running .. 565 static MutatorMutex* mutator_lock_ ACQUIRED_AFTER(instrument_entrypoints_lock_); 566 567 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 568 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 569 570 // Guards shutdown of the runtime. 571 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 572 573 // Guards background profiler global state. 574 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 575 576 // Guards trace (ie traceview) requests. 577 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 578 579 // Guards debugger recent allocation records. 580 static Mutex* alloc_tracker_lock_ ACQUIRED_AFTER(trace_lock_); 581 582 // Guards updates to instrumentation to ensure mutual exclusion of 583 // events like deoptimization requests. 584 // TODO: improve name, perhaps instrumentation_update_lock_. 585 static Mutex* deoptimization_lock_ ACQUIRED_AFTER(alloc_tracker_lock_); 586 587 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 588 // attaching and detaching. 589 static Mutex* thread_list_lock_ ACQUIRED_AFTER(deoptimization_lock_); 590 591 // Signaled when threads terminate. Used to determine when all non-daemons have terminated. 592 static ConditionVariable* thread_exit_cond_ GUARDED_BY(Locks::thread_list_lock_); 593 594 // Guards maintaining loading library data structures. 595 static Mutex* jni_libraries_lock_ ACQUIRED_AFTER(thread_list_lock_); 596 597 // Guards breakpoints. 598 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(jni_libraries_lock_); 599 600 // Guards lists of classes within the class linker. 601 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 602 603 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 604 // doesn't try to hold a higher level Mutex. 605 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 606 607 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 608 609 // Guard the allocation/deallocation of thread ids. 610 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 611 612 // Guards modification of the LDT on x86. 613 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 614 615 // Guards intern table. 616 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 617 618 // Guards reference processor. 619 static Mutex* reference_processor_lock_ ACQUIRED_AFTER(intern_table_lock_); 620 621 // Guards cleared references queue. 622 static Mutex* reference_queue_cleared_references_lock_ ACQUIRED_AFTER(reference_processor_lock_); 623 624 // Guards weak references queue. 625 static Mutex* reference_queue_weak_references_lock_ ACQUIRED_AFTER(reference_queue_cleared_references_lock_); 626 627 // Guards finalizer references queue. 628 static Mutex* reference_queue_finalizer_references_lock_ ACQUIRED_AFTER(reference_queue_weak_references_lock_); 629 630 // Guards phantom references queue. 631 static Mutex* reference_queue_phantom_references_lock_ ACQUIRED_AFTER(reference_queue_finalizer_references_lock_); 632 633 // Guards soft references queue. 634 static Mutex* reference_queue_soft_references_lock_ ACQUIRED_AFTER(reference_queue_phantom_references_lock_); 635 636 // Have an exclusive aborting thread. 637 static Mutex* abort_lock_ ACQUIRED_AFTER(reference_queue_soft_references_lock_); 638 639 // Allow mutual exclusion when manipulating Thread::suspend_count_. 640 // TODO: Does the trade-off of a per-thread lock make sense? 641 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 642 643 // One unexpected signal at a time lock. 644 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 645 646 // Guards the maps in mem_map. 647 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 648 649 // Have an exclusive logging thread. 650 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 651}; 652 653} // namespace art 654 655#endif // ART_RUNTIME_BASE_MUTEX_H_ 656