mutex.h revision 575e78c41ece0dec969d31f46be563d4eb7ae43b
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 ScopedContentionRecorder; 48class Thread; 49 50// LockLevel is used to impose a lock hierarchy [1] where acquisition of a Mutex at a higher or 51// equal level to a lock a thread holds is invalid. The lock hierarchy achieves a cycle free 52// partial ordering and thereby cause deadlock situations to fail checks. 53// 54// [1] http://www.drdobbs.com/parallel/use-lock-hierarchies-to-avoid-deadlock/204801163 55enum LockLevel { 56 kLoggingLock = 0, 57 kMemMapsLock, 58 kSwapMutexesLock, 59 kUnexpectedSignalLock, 60 kThreadSuspendCountLock, 61 kAbortLock, 62 kJdwpSocketLock, 63 kReferenceQueueSoftReferencesLock, 64 kReferenceQueuePhantomReferencesLock, 65 kReferenceQueueFinalizerReferencesLock, 66 kReferenceQueueWeakReferencesLock, 67 kReferenceQueueClearedReferencesLock, 68 kReferenceProcessorLock, 69 kRosAllocGlobalLock, 70 kRosAllocBracketLock, 71 kRosAllocBulkFreeLock, 72 kAllocSpaceLock, 73 kDexFileMethodInlinerLock, 74 kDexFileToMethodInlinerMapLock, 75 kMarkSweepMarkStackLock, 76 kTransactionLogLock, 77 kInternTableLock, 78 kOatFileSecondaryLookupLock, 79 kDefaultMutexLevel, 80 kMarkSweepLargeObjectLock, 81 kPinTableLock, 82 kJdwpObjectRegistryLock, 83 kModifyLdtLock, 84 kAllocatedThreadIdsLock, 85 kMonitorPoolLock, 86 kClassLinkerClassesLock, 87 kBreakpointLock, 88 kMonitorLock, 89 kMonitorListLock, 90 kJniLoadLibraryLock, 91 kThreadListLock, 92 kBreakpointInvokeLock, 93 kAllocTrackerLock, 94 kDeoptimizationLock, 95 kProfilerLock, 96 kJdwpEventListLock, 97 kJdwpAttachLock, 98 kJdwpStartLock, 99 kRuntimeShutdownLock, 100 kTraceLock, 101 kHeapBitmapLock, 102 kMutatorLock, 103 kInstrumentEntrypointsLock, 104 kThreadListSuspendThreadLock, 105 kZygoteCreationLock, 106 107 kLockLevelCount // Must come last. 108}; 109std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 110 111const bool kDebugLocking = kIsDebugBuild; 112 113// Record Log contention information, dumpable via SIGQUIT. 114#ifdef ART_USE_FUTEXES 115// To enable lock contention logging, set this to true. 116const bool kLogLockContentions = false; 117#else 118// Keep this false as lock contention logging is supported only with 119// futex. 120const bool kLogLockContentions = false; 121#endif 122const size_t kContentionLogSize = 4; 123const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 124const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 125 126// Base class for all Mutex implementations 127class BaseMutex { 128 public: 129 const char* GetName() const { 130 return name_; 131 } 132 133 virtual bool IsMutex() const { return false; } 134 virtual bool IsReaderWriterMutex() const { return false; } 135 136 virtual void Dump(std::ostream& os) const = 0; 137 138 static void DumpAll(std::ostream& os); 139 140 protected: 141 friend class ConditionVariable; 142 143 BaseMutex(const char* name, LockLevel level); 144 virtual ~BaseMutex(); 145 void RegisterAsLocked(Thread* self); 146 void RegisterAsUnlocked(Thread* self); 147 void CheckSafeToWait(Thread* self); 148 149 friend class ScopedContentionRecorder; 150 151 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 152 void DumpContention(std::ostream& os) const; 153 154 const LockLevel level_; // Support for lock hierarchy. 155 const char* const name_; 156 157 // A log entry that records contention but makes no guarantee that either tid will be held live. 158 struct ContentionLogEntry { 159 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 160 uint64_t blocked_tid; 161 uint64_t owner_tid; 162 AtomicInteger count; 163 }; 164 struct ContentionLogData { 165 ContentionLogEntry contention_log[kContentionLogSize]; 166 // The next entry in the contention log to be updated. Value ranges from 0 to 167 // kContentionLogSize - 1. 168 AtomicInteger cur_content_log_entry; 169 // Number of times the Mutex has been contended. 170 AtomicInteger contention_count; 171 // Sum of time waited by all contenders in ns. 172 Atomic<uint64_t> wait_time; 173 void AddToWaitTime(uint64_t value); 174 ContentionLogData() : wait_time(0) {} 175 }; 176 ContentionLogData contention_log_data_[kContentionLogDataSize]; 177 178 public: 179 bool HasEverContended() const { 180 if (kLogLockContentions) { 181 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 182 } 183 return false; 184 } 185}; 186 187// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 188// exclusive access to what it guards. A Mutex can be in one of two states: 189// - Free - not owned by any thread, 190// - Exclusive - owned by a single thread. 191// 192// The effect of locking and unlocking operations on the state is: 193// State | ExclusiveLock | ExclusiveUnlock 194// ------------------------------------------- 195// Free | Exclusive | error 196// Exclusive | Block* | Free 197// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 198// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 199std::ostream& operator<<(std::ostream& os, const Mutex& mu); 200class LOCKABLE Mutex : public BaseMutex { 201 public: 202 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 203 ~Mutex(); 204 205 virtual bool IsMutex() const { return true; } 206 207 // Block until mutex is free then acquire exclusive access. 208 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 209 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 210 211 // Returns true if acquires exclusive access, false otherwise. 212 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 213 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 214 215 // Release exclusive access. 216 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 217 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 218 219 // Is the current thread the exclusive holder of the Mutex. 220 bool IsExclusiveHeld(const Thread* self) const; 221 222 // Assert that the Mutex is exclusively held by the current thread. 223 void AssertExclusiveHeld(const Thread* self) { 224 if (kDebugLocking && (gAborting == 0)) { 225 CHECK(IsExclusiveHeld(self)) << *this; 226 } 227 } 228 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 229 230 // Assert that the Mutex is not held by the current thread. 231 void AssertNotHeldExclusive(const Thread* self) { 232 if (kDebugLocking && (gAborting == 0)) { 233 CHECK(!IsExclusiveHeld(self)) << *this; 234 } 235 } 236 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 237 238 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 239 // than the owner. 240 uint64_t GetExclusiveOwnerTid() const; 241 242 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 243 unsigned int GetDepth() const { 244 return recursion_count_; 245 } 246 247 virtual void Dump(std::ostream& os) const; 248 249 private: 250#if ART_USE_FUTEXES 251 // 0 is unheld, 1 is held. 252 AtomicInteger state_; 253 // Exclusive owner. 254 volatile uint64_t exclusive_owner_; 255 // Number of waiting contenders. 256 AtomicInteger num_contenders_; 257#else 258 pthread_mutex_t mutex_; 259 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 260#endif 261 const bool recursive_; // Can the lock be recursively held? 262 unsigned int recursion_count_; 263 friend class ConditionVariable; 264 DISALLOW_COPY_AND_ASSIGN(Mutex); 265}; 266 267// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 268// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 269// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 270// condition variable. A ReaderWriterMutex can be in one of three states: 271// - Free - not owned by any thread, 272// - Exclusive - owned by a single thread, 273// - Shared(n) - shared amongst n threads. 274// 275// The effect of locking and unlocking operations on the state is: 276// 277// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 278// ---------------------------------------------------------------------------- 279// Free | Exclusive | error | SharedLock(1) | error 280// Exclusive | Block | Free | Block | error 281// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 282// * for large values of n the SharedLock may block. 283std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 284class LOCKABLE ReaderWriterMutex : public BaseMutex { 285 public: 286 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 287 ~ReaderWriterMutex(); 288 289 virtual bool IsReaderWriterMutex() const { return true; } 290 291 // Block until ReaderWriterMutex is free then acquire exclusive access. 292 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 293 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 294 295 // Release exclusive access. 296 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 297 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 298 299 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 300 // or false if timeout is reached. 301#if HAVE_TIMED_RWLOCK 302 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 303 EXCLUSIVE_TRYLOCK_FUNCTION(true); 304#endif 305 306 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 307 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 308 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 309 310 // Try to acquire share of ReaderWriterMutex. 311 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 312 313 // Release a share of the access. 314 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 315 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 316 317 // Is the current thread the exclusive holder of the ReaderWriterMutex. 318 bool IsExclusiveHeld(const Thread* self) const; 319 320 // Assert the current thread has exclusive access to the ReaderWriterMutex. 321 void AssertExclusiveHeld(const Thread* self) { 322 if (kDebugLocking && (gAborting == 0)) { 323 CHECK(IsExclusiveHeld(self)) << *this; 324 } 325 } 326 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 327 328 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 329 void AssertNotExclusiveHeld(const Thread* self) { 330 if (kDebugLocking && (gAborting == 0)) { 331 CHECK(!IsExclusiveHeld(self)) << *this; 332 } 333 } 334 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 335 336 // Is the current thread a shared holder of the ReaderWriterMutex. 337 bool IsSharedHeld(const Thread* self) const; 338 339 // Assert the current thread has shared access to the ReaderWriterMutex. 340 void AssertSharedHeld(const Thread* self) { 341 if (kDebugLocking && (gAborting == 0)) { 342 // TODO: we can only assert this well when self != NULL. 343 CHECK(IsSharedHeld(self) || self == NULL) << *this; 344 } 345 } 346 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 347 348 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 349 // mode. 350 void AssertNotHeld(const Thread* self) { 351 if (kDebugLocking && (gAborting == 0)) { 352 CHECK(!IsSharedHeld(self)) << *this; 353 } 354 } 355 356 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 357 // than the owner. 358 uint64_t GetExclusiveOwnerTid() const; 359 360 virtual void Dump(std::ostream& os) const; 361 362 private: 363#if ART_USE_FUTEXES 364 // Out-of-inline path for handling contention for a SharedLock. 365 void HandleSharedLockContention(Thread* self, int32_t cur_state); 366 367 // -1 implies held exclusive, +ve shared held by state_ many owners. 368 AtomicInteger state_; 369 // Exclusive owner. Modification guarded by this mutex. 370 volatile uint64_t exclusive_owner_; 371 // Number of contenders waiting for a reader share. 372 AtomicInteger num_pending_readers_; 373 // Number of contenders waiting to be the writer. 374 AtomicInteger num_pending_writers_; 375#else 376 pthread_rwlock_t rwlock_; 377 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 378#endif 379 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 380}; 381 382// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 383// (Signal) or all at once (Broadcast). 384class ConditionVariable { 385 public: 386 explicit ConditionVariable(const char* name, Mutex& mutex); 387 ~ConditionVariable(); 388 389 void Broadcast(Thread* self); 390 void Signal(Thread* self); 391 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 392 // pointer copy, thereby defeating annotalysis. 393 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 394 bool TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 395 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 396 // when waiting. 397 // TODO: remove this. 398 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 399 400 private: 401 const char* const name_; 402 // The Mutex being used by waiters. It is an error to mix condition variables between different 403 // Mutexes. 404 Mutex& guard_; 405#if ART_USE_FUTEXES 406 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 407 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 408 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 409 // without guard_ held. 410 AtomicInteger sequence_; 411 // Number of threads that have come into to wait, not the length of the waiters on the futex as 412 // waiters may have been requeued onto guard_. Guarded by guard_. 413 volatile int32_t num_waiters_; 414#else 415 pthread_cond_t cond_; 416#endif 417 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 418}; 419 420// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 421// upon destruction. 422class SCOPED_LOCKABLE MutexLock { 423 public: 424 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 425 mu_.ExclusiveLock(self_); 426 } 427 428 ~MutexLock() UNLOCK_FUNCTION() { 429 mu_.ExclusiveUnlock(self_); 430 } 431 432 private: 433 Thread* const self_; 434 Mutex& mu_; 435 DISALLOW_COPY_AND_ASSIGN(MutexLock); 436}; 437// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 438#define MutexLock(x) static_assert(0, "MutexLock declaration missing variable name") 439 440// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 441// construction and releases it upon destruction. 442class SCOPED_LOCKABLE ReaderMutexLock { 443 public: 444 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 445 self_(self), mu_(mu) { 446 mu_.SharedLock(self_); 447 } 448 449 ~ReaderMutexLock() UNLOCK_FUNCTION() { 450 mu_.SharedUnlock(self_); 451 } 452 453 private: 454 Thread* const self_; 455 ReaderWriterMutex& mu_; 456 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 457}; 458// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 459// "ReaderMutexLock mu(lock)". 460#define ReaderMutexLock(x) static_assert(0, "ReaderMutexLock declaration missing variable name") 461 462// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 463// construction and releases it upon destruction. 464class SCOPED_LOCKABLE WriterMutexLock { 465 public: 466 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 467 self_(self), mu_(mu) { 468 mu_.ExclusiveLock(self_); 469 } 470 471 ~WriterMutexLock() UNLOCK_FUNCTION() { 472 mu_.ExclusiveUnlock(self_); 473 } 474 475 private: 476 Thread* const self_; 477 ReaderWriterMutex& mu_; 478 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 479}; 480// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 481// "WriterMutexLock mu(lock)". 482#define WriterMutexLock(x) static_assert(0, "WriterMutexLock declaration missing variable name") 483 484// Global mutexes corresponding to the levels above. 485class Locks { 486 public: 487 static void Init(); 488 489 // There's a potential race for two threads to try to suspend each other and for both of them 490 // to succeed and get blocked becoming runnable. This lock ensures that only one thread is 491 // requesting suspension of another at any time. As the the thread list suspend thread logic 492 // transitions to runnable, if the current thread were tried to be suspended then this thread 493 // would block holding this lock until it could safely request thread suspension of the other 494 // thread without that thread having a suspension request against this thread. This avoids a 495 // potential deadlock cycle. 496 static Mutex* thread_list_suspend_thread_lock_; 497 498 // Guards allocation entrypoint instrumenting. 499 static Mutex* instrument_entrypoints_lock_ ACQUIRED_AFTER(thread_list_suspend_thread_lock_); 500 501 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 502 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 503 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 504 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 505 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 506 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 507 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 508 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 509 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 510 // chance to acquire the lock. 511 // 512 // Thread suspension: 513 // Shared users | Exclusive user 514 // (holding mutator lock and in kRunnable state) | .. running .. 515 // .. running .. | Request thread suspension by: 516 // .. running .. | - acquiring thread_suspend_count_lock_ 517 // .. running .. | - incrementing Thread::suspend_count_ on 518 // .. running .. | all mutator threads 519 // .. running .. | - releasing thread_suspend_count_lock_ 520 // .. running .. | Block trying to acquire exclusive mutator lock 521 // Poll Thread::suspend_count_ and enter full | .. blocked .. 522 // suspend code. | .. blocked .. 523 // Change state to kSuspended | .. blocked .. 524 // x: Release share on mutator_lock_ | Carry out exclusive access 525 // Acquire thread_suspend_count_lock_ | .. exclusive .. 526 // while Thread::suspend_count_ > 0 | .. exclusive .. 527 // - wait on Thread::resume_cond_ | .. exclusive .. 528 // (releases thread_suspend_count_lock_) | .. exclusive .. 529 // .. waiting .. | Release mutator_lock_ 530 // .. waiting .. | Request thread resumption by: 531 // .. waiting .. | - acquiring thread_suspend_count_lock_ 532 // .. waiting .. | - decrementing Thread::suspend_count_ on 533 // .. waiting .. | all mutator threads 534 // .. waiting .. | - notifying on Thread::resume_cond_ 535 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 536 // Release thread_suspend_count_lock_ | .. running .. 537 // Acquire share on mutator_lock_ | .. running .. 538 // - This could block but the thread still | .. running .. 539 // has a state of kSuspended and so this | .. running .. 540 // isn't an issue. | .. running .. 541 // Acquire thread_suspend_count_lock_ | .. running .. 542 // - we poll here as we're transitioning into | .. running .. 543 // kRunnable and an individual thread suspend | .. running .. 544 // request (e.g for debugging) won't try | .. running .. 545 // to acquire the mutator lock (which would | .. running .. 546 // block as we hold the mutator lock). This | .. running .. 547 // poll ensures that if the suspender thought | .. running .. 548 // we were suspended by incrementing our | .. running .. 549 // Thread::suspend_count_ and then reading | .. running .. 550 // our state we go back to waiting on | .. running .. 551 // Thread::resume_cond_. | .. running .. 552 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 553 // Release thread_suspend_count_lock_ | .. running .. 554 // if can_go_runnable | .. running .. 555 // Change state to kRunnable | .. running .. 556 // else | .. running .. 557 // Goto x | .. running .. 558 // .. running .. | .. running .. 559 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(instrument_entrypoints_lock_); 560 561 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 562 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 563 564 // Guards shutdown of the runtime. 565 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 566 567 // Guards background profiler global state. 568 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 569 570 // Guards trace (ie traceview) requests. 571 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 572 573 // Guards debugger recent allocation records. 574 static Mutex* alloc_tracker_lock_ ACQUIRED_AFTER(trace_lock_); 575 576 // Guards updates to instrumentation to ensure mutual exclusion of 577 // events like deoptimization requests. 578 // TODO: improve name, perhaps instrumentation_update_lock_. 579 static Mutex* deoptimization_lock_ ACQUIRED_AFTER(alloc_tracker_lock_); 580 581 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 582 // attaching and detaching. 583 static Mutex* thread_list_lock_ ACQUIRED_AFTER(deoptimization_lock_); 584 585 // Guards maintaining loading library data structures. 586 static Mutex* jni_libraries_lock_ ACQUIRED_AFTER(thread_list_lock_); 587 588 // Guards breakpoints. 589 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(jni_libraries_lock_); 590 591 // Guards lists of classes within the class linker. 592 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 593 594 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 595 // doesn't try to hold a higher level Mutex. 596 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 597 598 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 599 600 // Guard the allocation/deallocation of thread ids. 601 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 602 603 // Guards modification of the LDT on x86. 604 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 605 606 // Guards intern table. 607 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 608 609 // Guards reference processor. 610 static Mutex* reference_processor_lock_ ACQUIRED_AFTER(intern_table_lock_); 611 612 // Guards cleared references queue. 613 static Mutex* reference_queue_cleared_references_lock_ ACQUIRED_AFTER(reference_processor_lock_); 614 615 // Guards weak references queue. 616 static Mutex* reference_queue_weak_references_lock_ ACQUIRED_AFTER(reference_queue_cleared_references_lock_); 617 618 // Guards finalizer references queue. 619 static Mutex* reference_queue_finalizer_references_lock_ ACQUIRED_AFTER(reference_queue_weak_references_lock_); 620 621 // Guards phantom references queue. 622 static Mutex* reference_queue_phantom_references_lock_ ACQUIRED_AFTER(reference_queue_finalizer_references_lock_); 623 624 // Guards soft references queue. 625 static Mutex* reference_queue_soft_references_lock_ ACQUIRED_AFTER(reference_queue_phantom_references_lock_); 626 627 // Have an exclusive aborting thread. 628 static Mutex* abort_lock_ ACQUIRED_AFTER(reference_queue_soft_references_lock_); 629 630 // Allow mutual exclusion when manipulating Thread::suspend_count_. 631 // TODO: Does the trade-off of a per-thread lock make sense? 632 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 633 634 // One unexpected signal at a time lock. 635 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 636 637 // Guards the maps in mem_map. 638 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 639 640 // Have an exclusive logging thread. 641 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 642}; 643 644} // namespace art 645 646#endif // ART_RUNTIME_BASE_MUTEX_H_ 647