mutex.h revision e5f13e57ff8fa36342beb33830b3ec5942a61cca
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 kRegionSpaceRegionLock, 64 kReferenceQueueSoftReferencesLock, 65 kReferenceQueuePhantomReferencesLock, 66 kReferenceQueueFinalizerReferencesLock, 67 kReferenceQueueWeakReferencesLock, 68 kReferenceQueueClearedReferencesLock, 69 kReferenceProcessorLock, 70 kJitCodeCacheLock, 71 kRosAllocGlobalLock, 72 kRosAllocBracketLock, 73 kRosAllocBulkFreeLock, 74 kAllocSpaceLock, 75 kBumpPointerSpaceBlockLock, 76 kDexFileMethodInlinerLock, 77 kDexFileToMethodInlinerMapLock, 78 kMarkSweepMarkStackLock, 79 kTransactionLogLock, 80 kInternTableLock, 81 kOatFileSecondaryLookupLock, 82 kDefaultMutexLevel, 83 kMarkSweepLargeObjectLock, 84 kPinTableLock, 85 kJdwpObjectRegistryLock, 86 kModifyLdtLock, 87 kAllocatedThreadIdsLock, 88 kMonitorPoolLock, 89 kClassLinkerClassesLock, 90 kBreakpointLock, 91 kMonitorLock, 92 kMonitorListLock, 93 kJniLoadLibraryLock, 94 kThreadListLock, 95 kBreakpointInvokeLock, 96 kAllocTrackerLock, 97 kDeoptimizationLock, 98 kProfilerLock, 99 kJdwpEventListLock, 100 kJdwpAttachLock, 101 kJdwpStartLock, 102 kRuntimeShutdownLock, 103 kTraceLock, 104 kHeapBitmapLock, 105 kMutatorLock, 106 kInstrumentEntrypointsLock, 107 kZygoteCreationLock, 108 109 kLockLevelCount // Must come last. 110}; 111std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 112 113const bool kDebugLocking = kIsDebugBuild; 114 115// Record Log contention information, dumpable via SIGQUIT. 116#ifdef ART_USE_FUTEXES 117// To enable lock contention logging, set this to true. 118const bool kLogLockContentions = false; 119#else 120// Keep this false as lock contention logging is supported only with 121// futex. 122const bool kLogLockContentions = false; 123#endif 124const size_t kContentionLogSize = 4; 125const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 126const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 127 128// Base class for all Mutex implementations 129class BaseMutex { 130 public: 131 const char* GetName() const { 132 return name_; 133 } 134 135 virtual bool IsMutex() const { return false; } 136 virtual bool IsReaderWriterMutex() const { return false; } 137 138 virtual void Dump(std::ostream& os) const = 0; 139 140 static void DumpAll(std::ostream& os); 141 142 protected: 143 friend class ConditionVariable; 144 145 BaseMutex(const char* name, LockLevel level); 146 virtual ~BaseMutex(); 147 void RegisterAsLocked(Thread* self); 148 void RegisterAsUnlocked(Thread* self); 149 void CheckSafeToWait(Thread* self); 150 151 friend class ScopedContentionRecorder; 152 153 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 154 void DumpContention(std::ostream& os) const; 155 156 const LockLevel level_; // Support for lock hierarchy. 157 const char* const name_; 158 159 // A log entry that records contention but makes no guarantee that either tid will be held live. 160 struct ContentionLogEntry { 161 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 162 uint64_t blocked_tid; 163 uint64_t owner_tid; 164 AtomicInteger count; 165 }; 166 struct ContentionLogData { 167 ContentionLogEntry contention_log[kContentionLogSize]; 168 // The next entry in the contention log to be updated. Value ranges from 0 to 169 // kContentionLogSize - 1. 170 AtomicInteger cur_content_log_entry; 171 // Number of times the Mutex has been contended. 172 AtomicInteger contention_count; 173 // Sum of time waited by all contenders in ns. 174 Atomic<uint64_t> wait_time; 175 void AddToWaitTime(uint64_t value); 176 ContentionLogData() : wait_time(0) {} 177 }; 178 ContentionLogData contention_log_data_[kContentionLogDataSize]; 179 180 public: 181 bool HasEverContended() const { 182 if (kLogLockContentions) { 183 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 184 } 185 return false; 186 } 187}; 188 189// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 190// exclusive access to what it guards. A Mutex can be in one of two states: 191// - Free - not owned by any thread, 192// - Exclusive - owned by a single thread. 193// 194// The effect of locking and unlocking operations on the state is: 195// State | ExclusiveLock | ExclusiveUnlock 196// ------------------------------------------- 197// Free | Exclusive | error 198// Exclusive | Block* | Free 199// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 200// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 201std::ostream& operator<<(std::ostream& os, const Mutex& mu); 202class LOCKABLE Mutex : public BaseMutex { 203 public: 204 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 205 ~Mutex(); 206 207 virtual bool IsMutex() const { return true; } 208 209 // Block until mutex is free then acquire exclusive access. 210 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 211 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 212 213 // Returns true if acquires exclusive access, false otherwise. 214 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 215 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 216 217 // Release exclusive access. 218 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 219 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 220 221 // Is the current thread the exclusive holder of the Mutex. 222 bool IsExclusiveHeld(const Thread* self) const; 223 224 // Assert that the Mutex is exclusively held by the current thread. 225 void AssertExclusiveHeld(const Thread* self) { 226 if (kDebugLocking && (gAborting == 0)) { 227 CHECK(IsExclusiveHeld(self)) << *this; 228 } 229 } 230 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 231 232 // Assert that the Mutex is not held by the current thread. 233 void AssertNotHeldExclusive(const Thread* self) { 234 if (kDebugLocking && (gAborting == 0)) { 235 CHECK(!IsExclusiveHeld(self)) << *this; 236 } 237 } 238 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 239 240 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 241 // than the owner. 242 uint64_t GetExclusiveOwnerTid() const; 243 244 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 245 unsigned int GetDepth() const { 246 return recursion_count_; 247 } 248 249 virtual void Dump(std::ostream& os) const; 250 251 private: 252#if ART_USE_FUTEXES 253 // 0 is unheld, 1 is held. 254 AtomicInteger state_; 255 // Exclusive owner. 256 volatile uint64_t exclusive_owner_; 257 // Number of waiting contenders. 258 AtomicInteger num_contenders_; 259#else 260 pthread_mutex_t mutex_; 261 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 262#endif 263 const bool recursive_; // Can the lock be recursively held? 264 unsigned int recursion_count_; 265 friend class ConditionVariable; 266 DISALLOW_COPY_AND_ASSIGN(Mutex); 267}; 268 269// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 270// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 271// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 272// condition variable. A ReaderWriterMutex can be in one of three states: 273// - Free - not owned by any thread, 274// - Exclusive - owned by a single thread, 275// - Shared(n) - shared amongst n threads. 276// 277// The effect of locking and unlocking operations on the state is: 278// 279// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 280// ---------------------------------------------------------------------------- 281// Free | Exclusive | error | SharedLock(1) | error 282// Exclusive | Block | Free | Block | error 283// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 284// * for large values of n the SharedLock may block. 285std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 286class LOCKABLE ReaderWriterMutex : public BaseMutex { 287 public: 288 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 289 ~ReaderWriterMutex(); 290 291 virtual bool IsReaderWriterMutex() const { return true; } 292 293 // Block until ReaderWriterMutex is free then acquire exclusive access. 294 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 295 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 296 297 // Release exclusive access. 298 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 299 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 300 301 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 302 // or false if timeout is reached. 303#if HAVE_TIMED_RWLOCK 304 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 305 EXCLUSIVE_TRYLOCK_FUNCTION(true); 306#endif 307 308 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 309 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 310 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 311 312 // Try to acquire share of ReaderWriterMutex. 313 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 314 315 // Release a share of the access. 316 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 317 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 318 319 // Is the current thread the exclusive holder of the ReaderWriterMutex. 320 bool IsExclusiveHeld(const Thread* self) const; 321 322 // Assert the current thread has exclusive access to the ReaderWriterMutex. 323 void AssertExclusiveHeld(const Thread* self) { 324 if (kDebugLocking && (gAborting == 0)) { 325 CHECK(IsExclusiveHeld(self)) << *this; 326 } 327 } 328 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 329 330 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 331 void AssertNotExclusiveHeld(const Thread* self) { 332 if (kDebugLocking && (gAborting == 0)) { 333 CHECK(!IsExclusiveHeld(self)) << *this; 334 } 335 } 336 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 337 338 // Is the current thread a shared holder of the ReaderWriterMutex. 339 bool IsSharedHeld(const Thread* self) const; 340 341 // Assert the current thread has shared access to the ReaderWriterMutex. 342 void AssertSharedHeld(const Thread* self) { 343 if (kDebugLocking && (gAborting == 0)) { 344 // TODO: we can only assert this well when self != NULL. 345 CHECK(IsSharedHeld(self) || self == NULL) << *this; 346 } 347 } 348 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 349 350 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 351 // mode. 352 void AssertNotHeld(const Thread* self) { 353 if (kDebugLocking && (gAborting == 0)) { 354 CHECK(!IsSharedHeld(self)) << *this; 355 } 356 } 357 358 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 359 // than the owner. 360 uint64_t GetExclusiveOwnerTid() const; 361 362 virtual void Dump(std::ostream& os) const; 363 364 private: 365#if ART_USE_FUTEXES 366 // Out-of-inline path for handling contention for a SharedLock. 367 void HandleSharedLockContention(Thread* self, int32_t cur_state); 368 369 // -1 implies held exclusive, +ve shared held by state_ many owners. 370 AtomicInteger state_; 371 // Exclusive owner. Modification guarded by this mutex. 372 volatile uint64_t exclusive_owner_; 373 // Number of contenders waiting for a reader share. 374 AtomicInteger num_pending_readers_; 375 // Number of contenders waiting to be the writer. 376 AtomicInteger num_pending_writers_; 377#else 378 pthread_rwlock_t rwlock_; 379 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 380#endif 381 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 382}; 383 384// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 385// (Signal) or all at once (Broadcast). 386class ConditionVariable { 387 public: 388 explicit ConditionVariable(const char* name, Mutex& mutex); 389 ~ConditionVariable(); 390 391 void Broadcast(Thread* self); 392 void Signal(Thread* self); 393 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 394 // pointer copy, thereby defeating annotalysis. 395 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 396 bool TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 397 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 398 // when waiting. 399 // TODO: remove this. 400 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 401 402 private: 403 const char* const name_; 404 // The Mutex being used by waiters. It is an error to mix condition variables between different 405 // Mutexes. 406 Mutex& guard_; 407#if ART_USE_FUTEXES 408 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 409 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 410 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 411 // without guard_ held. 412 AtomicInteger sequence_; 413 // Number of threads that have come into to wait, not the length of the waiters on the futex as 414 // waiters may have been requeued onto guard_. Guarded by guard_. 415 volatile int32_t num_waiters_; 416#else 417 pthread_cond_t cond_; 418#endif 419 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 420}; 421 422// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 423// upon destruction. 424class SCOPED_LOCKABLE MutexLock { 425 public: 426 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 427 mu_.ExclusiveLock(self_); 428 } 429 430 ~MutexLock() UNLOCK_FUNCTION() { 431 mu_.ExclusiveUnlock(self_); 432 } 433 434 private: 435 Thread* const self_; 436 Mutex& mu_; 437 DISALLOW_COPY_AND_ASSIGN(MutexLock); 438}; 439// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 440#define MutexLock(x) static_assert(0, "MutexLock declaration missing variable name") 441 442// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 443// construction and releases it upon destruction. 444class SCOPED_LOCKABLE ReaderMutexLock { 445 public: 446 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 447 self_(self), mu_(mu) { 448 mu_.SharedLock(self_); 449 } 450 451 ~ReaderMutexLock() UNLOCK_FUNCTION() { 452 mu_.SharedUnlock(self_); 453 } 454 455 private: 456 Thread* const self_; 457 ReaderWriterMutex& mu_; 458 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 459}; 460// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 461// "ReaderMutexLock mu(lock)". 462#define ReaderMutexLock(x) static_assert(0, "ReaderMutexLock declaration missing variable name") 463 464// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 465// construction and releases it upon destruction. 466class SCOPED_LOCKABLE WriterMutexLock { 467 public: 468 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 469 self_(self), mu_(mu) { 470 mu_.ExclusiveLock(self_); 471 } 472 473 ~WriterMutexLock() UNLOCK_FUNCTION() { 474 mu_.ExclusiveUnlock(self_); 475 } 476 477 private: 478 Thread* const self_; 479 ReaderWriterMutex& mu_; 480 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 481}; 482// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 483// "WriterMutexLock mu(lock)". 484#define WriterMutexLock(x) static_assert(0, "WriterMutexLock declaration missing variable name") 485 486// Global mutexes corresponding to the levels above. 487class Locks { 488 public: 489 static void Init(); 490 491 // Guards allocation entrypoint instrumenting. 492 static Mutex* instrument_entrypoints_lock_; 493 494 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 495 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 496 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 497 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 498 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 499 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 500 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 501 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 502 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 503 // chance to acquire the lock. 504 // 505 // Thread suspension: 506 // Shared users | Exclusive user 507 // (holding mutator lock and in kRunnable state) | .. running .. 508 // .. running .. | Request thread suspension by: 509 // .. running .. | - acquiring thread_suspend_count_lock_ 510 // .. running .. | - incrementing Thread::suspend_count_ on 511 // .. running .. | all mutator threads 512 // .. running .. | - releasing thread_suspend_count_lock_ 513 // .. running .. | Block trying to acquire exclusive mutator lock 514 // Poll Thread::suspend_count_ and enter full | .. blocked .. 515 // suspend code. | .. blocked .. 516 // Change state to kSuspended | .. blocked .. 517 // x: Release share on mutator_lock_ | Carry out exclusive access 518 // Acquire thread_suspend_count_lock_ | .. exclusive .. 519 // while Thread::suspend_count_ > 0 | .. exclusive .. 520 // - wait on Thread::resume_cond_ | .. exclusive .. 521 // (releases thread_suspend_count_lock_) | .. exclusive .. 522 // .. waiting .. | Release mutator_lock_ 523 // .. waiting .. | Request thread resumption by: 524 // .. waiting .. | - acquiring thread_suspend_count_lock_ 525 // .. waiting .. | - decrementing Thread::suspend_count_ on 526 // .. waiting .. | all mutator threads 527 // .. waiting .. | - notifying on Thread::resume_cond_ 528 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 529 // Release thread_suspend_count_lock_ | .. running .. 530 // Acquire share on mutator_lock_ | .. running .. 531 // - This could block but the thread still | .. running .. 532 // has a state of kSuspended and so this | .. running .. 533 // isn't an issue. | .. running .. 534 // Acquire thread_suspend_count_lock_ | .. running .. 535 // - we poll here as we're transitioning into | .. running .. 536 // kRunnable and an individual thread suspend | .. running .. 537 // request (e.g for debugging) won't try | .. running .. 538 // to acquire the mutator lock (which would | .. running .. 539 // block as we hold the mutator lock). This | .. running .. 540 // poll ensures that if the suspender thought | .. running .. 541 // we were suspended by incrementing our | .. running .. 542 // Thread::suspend_count_ and then reading | .. running .. 543 // our state we go back to waiting on | .. running .. 544 // Thread::resume_cond_. | .. running .. 545 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 546 // Release thread_suspend_count_lock_ | .. running .. 547 // if can_go_runnable | .. running .. 548 // Change state to kRunnable | .. running .. 549 // else | .. running .. 550 // Goto x | .. running .. 551 // .. running .. | .. running .. 552 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(instrument_entrypoints_lock_); 553 554 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 555 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 556 557 // Guards shutdown of the runtime. 558 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 559 560 // Guards background profiler global state. 561 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 562 563 // Guards trace (ie traceview) requests. 564 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 565 566 // Guards debugger recent allocation records. 567 static Mutex* alloc_tracker_lock_ ACQUIRED_AFTER(trace_lock_); 568 569 // Guards updates to instrumentation to ensure mutual exclusion of 570 // events like deoptimization requests. 571 // TODO: improve name, perhaps instrumentation_update_lock_. 572 static Mutex* deoptimization_lock_ ACQUIRED_AFTER(alloc_tracker_lock_); 573 574 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 575 // attaching and detaching. 576 static Mutex* thread_list_lock_ ACQUIRED_AFTER(deoptimization_lock_); 577 578 // Guards maintaining loading library data structures. 579 static Mutex* jni_libraries_lock_ ACQUIRED_AFTER(thread_list_lock_); 580 581 // Guards breakpoints. 582 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(jni_libraries_lock_); 583 584 // Guards lists of classes within the class linker. 585 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 586 587 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 588 // doesn't try to hold a higher level Mutex. 589 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 590 591 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 592 593 // Guard the allocation/deallocation of thread ids. 594 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 595 596 // Guards modification of the LDT on x86. 597 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 598 599 // Guards intern table. 600 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 601 602 // Guards reference processor. 603 static Mutex* reference_processor_lock_ ACQUIRED_AFTER(intern_table_lock_); 604 605 // Guards cleared references queue. 606 static Mutex* reference_queue_cleared_references_lock_ ACQUIRED_AFTER(reference_processor_lock_); 607 608 // Guards weak references queue. 609 static Mutex* reference_queue_weak_references_lock_ ACQUIRED_AFTER(reference_queue_cleared_references_lock_); 610 611 // Guards finalizer references queue. 612 static Mutex* reference_queue_finalizer_references_lock_ ACQUIRED_AFTER(reference_queue_weak_references_lock_); 613 614 // Guards phantom references queue. 615 static Mutex* reference_queue_phantom_references_lock_ ACQUIRED_AFTER(reference_queue_finalizer_references_lock_); 616 617 // Guards soft references queue. 618 static Mutex* reference_queue_soft_references_lock_ ACQUIRED_AFTER(reference_queue_phantom_references_lock_); 619 620 // Have an exclusive aborting thread. 621 static Mutex* abort_lock_ ACQUIRED_AFTER(reference_queue_soft_references_lock_); 622 623 // Allow mutual exclusion when manipulating Thread::suspend_count_. 624 // TODO: Does the trade-off of a per-thread lock make sense? 625 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 626 627 // One unexpected signal at a time lock. 628 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 629 630 // Guards the maps in mem_map. 631 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 632 633 // Have an exclusive logging thread. 634 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 635}; 636 637} // namespace art 638 639#endif // ART_RUNTIME_BASE_MUTEX_H_ 640