mutex.h revision db978719dbcb73fc6acfd193561445c4462786b8
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 kZygoteCreationLock, 105 106 kLockLevelCount // Must come last. 107}; 108std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 109 110const bool kDebugLocking = kIsDebugBuild; 111 112// Record Log contention information, dumpable via SIGQUIT. 113#ifdef ART_USE_FUTEXES 114// To enable lock contention logging, set this to true. 115const bool kLogLockContentions = false; 116#else 117// Keep this false as lock contention logging is supported only with 118// futex. 119const bool kLogLockContentions = false; 120#endif 121const size_t kContentionLogSize = 4; 122const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 123const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 124 125// Base class for all Mutex implementations 126class BaseMutex { 127 public: 128 const char* GetName() const { 129 return name_; 130 } 131 132 virtual bool IsMutex() const { return false; } 133 virtual bool IsReaderWriterMutex() const { return false; } 134 135 virtual void Dump(std::ostream& os) const = 0; 136 137 static void DumpAll(std::ostream& os); 138 139 protected: 140 friend class ConditionVariable; 141 142 BaseMutex(const char* name, LockLevel level); 143 virtual ~BaseMutex(); 144 void RegisterAsLocked(Thread* self); 145 void RegisterAsUnlocked(Thread* self); 146 void CheckSafeToWait(Thread* self); 147 148 friend class ScopedContentionRecorder; 149 150 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 151 void DumpContention(std::ostream& os) const; 152 153 const LockLevel level_; // Support for lock hierarchy. 154 const char* const name_; 155 156 // A log entry that records contention but makes no guarantee that either tid will be held live. 157 struct ContentionLogEntry { 158 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 159 uint64_t blocked_tid; 160 uint64_t owner_tid; 161 AtomicInteger count; 162 }; 163 struct ContentionLogData { 164 ContentionLogEntry contention_log[kContentionLogSize]; 165 // The next entry in the contention log to be updated. Value ranges from 0 to 166 // kContentionLogSize - 1. 167 AtomicInteger cur_content_log_entry; 168 // Number of times the Mutex has been contended. 169 AtomicInteger contention_count; 170 // Sum of time waited by all contenders in ns. 171 Atomic<uint64_t> wait_time; 172 void AddToWaitTime(uint64_t value); 173 ContentionLogData() : wait_time(0) {} 174 }; 175 ContentionLogData contention_log_data_[kContentionLogDataSize]; 176 177 public: 178 bool HasEverContended() const { 179 if (kLogLockContentions) { 180 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 181 } 182 return false; 183 } 184}; 185 186// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 187// exclusive access to what it guards. A Mutex can be in one of two states: 188// - Free - not owned by any thread, 189// - Exclusive - owned by a single thread. 190// 191// The effect of locking and unlocking operations on the state is: 192// State | ExclusiveLock | ExclusiveUnlock 193// ------------------------------------------- 194// Free | Exclusive | error 195// Exclusive | Block* | Free 196// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 197// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 198std::ostream& operator<<(std::ostream& os, const Mutex& mu); 199class LOCKABLE Mutex : public BaseMutex { 200 public: 201 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 202 ~Mutex(); 203 204 virtual bool IsMutex() const { return true; } 205 206 // Block until mutex is free then acquire exclusive access. 207 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 208 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 209 210 // Returns true if acquires exclusive access, false otherwise. 211 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 212 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 213 214 // Release exclusive access. 215 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 216 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 217 218 // Is the current thread the exclusive holder of the Mutex. 219 bool IsExclusiveHeld(const Thread* self) const; 220 221 // Assert that the Mutex is exclusively held by the current thread. 222 void AssertExclusiveHeld(const Thread* self) { 223 if (kDebugLocking && (gAborting == 0)) { 224 CHECK(IsExclusiveHeld(self)) << *this; 225 } 226 } 227 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 228 229 // Assert that the Mutex is not held by the current thread. 230 void AssertNotHeldExclusive(const Thread* self) { 231 if (kDebugLocking && (gAborting == 0)) { 232 CHECK(!IsExclusiveHeld(self)) << *this; 233 } 234 } 235 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 236 237 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 238 // than the owner. 239 uint64_t GetExclusiveOwnerTid() const; 240 241 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 242 unsigned int GetDepth() const { 243 return recursion_count_; 244 } 245 246 virtual void Dump(std::ostream& os) const; 247 248 private: 249#if ART_USE_FUTEXES 250 // 0 is unheld, 1 is held. 251 AtomicInteger state_; 252 // Exclusive owner. 253 volatile uint64_t exclusive_owner_; 254 // Number of waiting contenders. 255 AtomicInteger num_contenders_; 256#else 257 pthread_mutex_t mutex_; 258 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 259#endif 260 const bool recursive_; // Can the lock be recursively held? 261 unsigned int recursion_count_; 262 friend class ConditionVariable; 263 DISALLOW_COPY_AND_ASSIGN(Mutex); 264}; 265 266// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 267// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 268// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 269// condition variable. A ReaderWriterMutex can be in one of three states: 270// - Free - not owned by any thread, 271// - Exclusive - owned by a single thread, 272// - Shared(n) - shared amongst n threads. 273// 274// The effect of locking and unlocking operations on the state is: 275// 276// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 277// ---------------------------------------------------------------------------- 278// Free | Exclusive | error | SharedLock(1) | error 279// Exclusive | Block | Free | Block | error 280// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 281// * for large values of n the SharedLock may block. 282std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 283class LOCKABLE ReaderWriterMutex : public BaseMutex { 284 public: 285 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 286 ~ReaderWriterMutex(); 287 288 virtual bool IsReaderWriterMutex() const { return true; } 289 290 // Block until ReaderWriterMutex is free then acquire exclusive access. 291 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 292 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 293 294 // Release exclusive access. 295 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 296 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 297 298 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 299 // or false if timeout is reached. 300#if HAVE_TIMED_RWLOCK 301 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 302 EXCLUSIVE_TRYLOCK_FUNCTION(true); 303#endif 304 305 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 306 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 307 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 308 309 // Try to acquire share of ReaderWriterMutex. 310 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 311 312 // Release a share of the access. 313 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 314 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 315 316 // Is the current thread the exclusive holder of the ReaderWriterMutex. 317 bool IsExclusiveHeld(const Thread* self) const; 318 319 // Assert the current thread has exclusive access to the ReaderWriterMutex. 320 void AssertExclusiveHeld(const Thread* self) { 321 if (kDebugLocking && (gAborting == 0)) { 322 CHECK(IsExclusiveHeld(self)) << *this; 323 } 324 } 325 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 326 327 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 328 void AssertNotExclusiveHeld(const Thread* self) { 329 if (kDebugLocking && (gAborting == 0)) { 330 CHECK(!IsExclusiveHeld(self)) << *this; 331 } 332 } 333 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 334 335 // Is the current thread a shared holder of the ReaderWriterMutex. 336 bool IsSharedHeld(const Thread* self) const; 337 338 // Assert the current thread has shared access to the ReaderWriterMutex. 339 void AssertSharedHeld(const Thread* self) { 340 if (kDebugLocking && (gAborting == 0)) { 341 // TODO: we can only assert this well when self != NULL. 342 CHECK(IsSharedHeld(self) || self == NULL) << *this; 343 } 344 } 345 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 346 347 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 348 // mode. 349 void AssertNotHeld(const Thread* self) { 350 if (kDebugLocking && (gAborting == 0)) { 351 CHECK(!IsSharedHeld(self)) << *this; 352 } 353 } 354 355 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 356 // than the owner. 357 uint64_t GetExclusiveOwnerTid() const; 358 359 virtual void Dump(std::ostream& os) const; 360 361 private: 362#if ART_USE_FUTEXES 363 // Out-of-inline path for handling contention for a SharedLock. 364 void HandleSharedLockContention(Thread* self, int32_t cur_state); 365 366 // -1 implies held exclusive, +ve shared held by state_ many owners. 367 AtomicInteger state_; 368 // Exclusive owner. Modification guarded by this mutex. 369 volatile uint64_t exclusive_owner_; 370 // Number of contenders waiting for a reader share. 371 AtomicInteger num_pending_readers_; 372 // Number of contenders waiting to be the writer. 373 AtomicInteger num_pending_writers_; 374#else 375 pthread_rwlock_t rwlock_; 376 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 377#endif 378 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 379}; 380 381// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 382// (Signal) or all at once (Broadcast). 383class ConditionVariable { 384 public: 385 explicit ConditionVariable(const char* name, Mutex& mutex); 386 ~ConditionVariable(); 387 388 void Broadcast(Thread* self); 389 void Signal(Thread* self); 390 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 391 // pointer copy, thereby defeating annotalysis. 392 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 393 bool TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 394 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 395 // when waiting. 396 // TODO: remove this. 397 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 398 399 private: 400 const char* const name_; 401 // The Mutex being used by waiters. It is an error to mix condition variables between different 402 // Mutexes. 403 Mutex& guard_; 404#if ART_USE_FUTEXES 405 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 406 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 407 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 408 // without guard_ held. 409 AtomicInteger sequence_; 410 // Number of threads that have come into to wait, not the length of the waiters on the futex as 411 // waiters may have been requeued onto guard_. Guarded by guard_. 412 volatile int32_t num_waiters_; 413#else 414 pthread_cond_t cond_; 415#endif 416 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 417}; 418 419// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 420// upon destruction. 421class SCOPED_LOCKABLE MutexLock { 422 public: 423 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 424 mu_.ExclusiveLock(self_); 425 } 426 427 ~MutexLock() UNLOCK_FUNCTION() { 428 mu_.ExclusiveUnlock(self_); 429 } 430 431 private: 432 Thread* const self_; 433 Mutex& mu_; 434 DISALLOW_COPY_AND_ASSIGN(MutexLock); 435}; 436// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 437#define MutexLock(x) static_assert(0, "MutexLock declaration missing variable name") 438 439// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 440// construction and releases it upon destruction. 441class SCOPED_LOCKABLE ReaderMutexLock { 442 public: 443 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 444 self_(self), mu_(mu) { 445 mu_.SharedLock(self_); 446 } 447 448 ~ReaderMutexLock() UNLOCK_FUNCTION() { 449 mu_.SharedUnlock(self_); 450 } 451 452 private: 453 Thread* const self_; 454 ReaderWriterMutex& mu_; 455 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 456}; 457// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 458// "ReaderMutexLock mu(lock)". 459#define ReaderMutexLock(x) static_assert(0, "ReaderMutexLock declaration missing variable name") 460 461// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 462// construction and releases it upon destruction. 463class SCOPED_LOCKABLE WriterMutexLock { 464 public: 465 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 466 self_(self), mu_(mu) { 467 mu_.ExclusiveLock(self_); 468 } 469 470 ~WriterMutexLock() UNLOCK_FUNCTION() { 471 mu_.ExclusiveUnlock(self_); 472 } 473 474 private: 475 Thread* const self_; 476 ReaderWriterMutex& mu_; 477 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 478}; 479// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 480// "WriterMutexLock mu(lock)". 481#define WriterMutexLock(x) static_assert(0, "WriterMutexLock declaration missing variable name") 482 483// Global mutexes corresponding to the levels above. 484class Locks { 485 public: 486 static void Init(); 487 488 // Guards allocation entrypoint instrumenting. 489 static Mutex* instrument_entrypoints_lock_; 490 491 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 492 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 493 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 494 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 495 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 496 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 497 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 498 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 499 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 500 // chance to acquire the lock. 501 // 502 // Thread suspension: 503 // Shared users | Exclusive user 504 // (holding mutator lock and in kRunnable state) | .. running .. 505 // .. running .. | Request thread suspension by: 506 // .. running .. | - acquiring thread_suspend_count_lock_ 507 // .. running .. | - incrementing Thread::suspend_count_ on 508 // .. running .. | all mutator threads 509 // .. running .. | - releasing thread_suspend_count_lock_ 510 // .. running .. | Block trying to acquire exclusive mutator lock 511 // Poll Thread::suspend_count_ and enter full | .. blocked .. 512 // suspend code. | .. blocked .. 513 // Change state to kSuspended | .. blocked .. 514 // x: Release share on mutator_lock_ | Carry out exclusive access 515 // Acquire thread_suspend_count_lock_ | .. exclusive .. 516 // while Thread::suspend_count_ > 0 | .. exclusive .. 517 // - wait on Thread::resume_cond_ | .. exclusive .. 518 // (releases thread_suspend_count_lock_) | .. exclusive .. 519 // .. waiting .. | Release mutator_lock_ 520 // .. waiting .. | Request thread resumption by: 521 // .. waiting .. | - acquiring thread_suspend_count_lock_ 522 // .. waiting .. | - decrementing Thread::suspend_count_ on 523 // .. waiting .. | all mutator threads 524 // .. waiting .. | - notifying on Thread::resume_cond_ 525 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 526 // Release thread_suspend_count_lock_ | .. running .. 527 // Acquire share on mutator_lock_ | .. running .. 528 // - This could block but the thread still | .. running .. 529 // has a state of kSuspended and so this | .. running .. 530 // isn't an issue. | .. running .. 531 // Acquire thread_suspend_count_lock_ | .. running .. 532 // - we poll here as we're transitioning into | .. running .. 533 // kRunnable and an individual thread suspend | .. running .. 534 // request (e.g for debugging) won't try | .. running .. 535 // to acquire the mutator lock (which would | .. running .. 536 // block as we hold the mutator lock). This | .. running .. 537 // poll ensures that if the suspender thought | .. running .. 538 // we were suspended by incrementing our | .. running .. 539 // Thread::suspend_count_ and then reading | .. running .. 540 // our state we go back to waiting on | .. running .. 541 // Thread::resume_cond_. | .. running .. 542 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 543 // Release thread_suspend_count_lock_ | .. running .. 544 // if can_go_runnable | .. running .. 545 // Change state to kRunnable | .. running .. 546 // else | .. running .. 547 // Goto x | .. running .. 548 // .. running .. | .. running .. 549 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(instrument_entrypoints_lock_); 550 551 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 552 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 553 554 // Guards shutdown of the runtime. 555 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 556 557 // Guards background profiler global state. 558 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 559 560 // Guards trace (ie traceview) requests. 561 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 562 563 // Guards debugger recent allocation records. 564 static Mutex* alloc_tracker_lock_ ACQUIRED_AFTER(trace_lock_); 565 566 // Guards updates to instrumentation to ensure mutual exclusion of 567 // events like deoptimization requests. 568 // TODO: improve name, perhaps instrumentation_update_lock_. 569 static Mutex* deoptimization_lock_ ACQUIRED_AFTER(alloc_tracker_lock_); 570 571 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 572 // attaching and detaching. 573 static Mutex* thread_list_lock_ ACQUIRED_AFTER(deoptimization_lock_); 574 575 // Guards maintaining loading library data structures. 576 static Mutex* jni_libraries_lock_ ACQUIRED_AFTER(thread_list_lock_); 577 578 // Guards breakpoints. 579 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(jni_libraries_lock_); 580 581 // Guards lists of classes within the class linker. 582 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 583 584 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 585 // doesn't try to hold a higher level Mutex. 586 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 587 588 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 589 590 // Guard the allocation/deallocation of thread ids. 591 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 592 593 // Guards modification of the LDT on x86. 594 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 595 596 // Guards intern table. 597 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 598 599 // Guards reference processor. 600 static Mutex* reference_processor_lock_ ACQUIRED_AFTER(intern_table_lock_); 601 602 // Guards cleared references queue. 603 static Mutex* reference_queue_cleared_references_lock_ ACQUIRED_AFTER(reference_processor_lock_); 604 605 // Guards weak references queue. 606 static Mutex* reference_queue_weak_references_lock_ ACQUIRED_AFTER(reference_queue_cleared_references_lock_); 607 608 // Guards finalizer references queue. 609 static Mutex* reference_queue_finalizer_references_lock_ ACQUIRED_AFTER(reference_queue_weak_references_lock_); 610 611 // Guards phantom references queue. 612 static Mutex* reference_queue_phantom_references_lock_ ACQUIRED_AFTER(reference_queue_finalizer_references_lock_); 613 614 // Guards soft references queue. 615 static Mutex* reference_queue_soft_references_lock_ ACQUIRED_AFTER(reference_queue_phantom_references_lock_); 616 617 // Have an exclusive aborting thread. 618 static Mutex* abort_lock_ ACQUIRED_AFTER(reference_queue_soft_references_lock_); 619 620 // Allow mutual exclusion when manipulating Thread::suspend_count_. 621 // TODO: Does the trade-off of a per-thread lock make sense? 622 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 623 624 // One unexpected signal at a time lock. 625 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 626 627 // Guards the maps in mem_map. 628 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 629 630 // Have an exclusive logging thread. 631 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 632}; 633 634} // namespace art 635 636#endif // ART_RUNTIME_BASE_MUTEX_H_ 637