mutex.h revision 6093a5c277e54bcd949dd6fac7b3856e5f371d06
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 kRosAllocGlobalLock, 64 kRosAllocBracketLock, 65 kRosAllocBulkFreeLock, 66 kAllocSpaceLock, 67 kReferenceProcessorLock, 68 kDexFileMethodInlinerLock, 69 kDexFileToMethodInlinerMapLock, 70 kMarkSweepMarkStackLock, 71 kTransactionLogLock, 72 kInternTableLock, 73 kDefaultMutexLevel, 74 kMarkSweepLargeObjectLock, 75 kPinTableLock, 76 kLoadLibraryLock, 77 kJdwpObjectRegistryLock, 78 kModifyLdtLock, 79 kAllocatedThreadIdsLock, 80 kMonitorPoolLock, 81 kClassLinkerClassesLock, 82 kBreakpointLock, 83 kMonitorLock, 84 kMonitorListLock, 85 kThreadListLock, 86 kBreakpointInvokeLock, 87 kDeoptimizationLock, 88 kTraceLock, 89 kProfilerLock, 90 kJdwpEventListLock, 91 kJdwpAttachLock, 92 kJdwpStartLock, 93 kRuntimeShutdownLock, 94 kHeapBitmapLock, 95 kMutatorLock, 96 kThreadListSuspendThreadLock, 97 kZygoteCreationLock, 98 99 kLockLevelCount // Must come last. 100}; 101std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 102 103const bool kDebugLocking = kIsDebugBuild; 104 105// Record Log contention information, dumpable via SIGQUIT. 106#ifdef ART_USE_FUTEXES 107// To enable lock contention logging, set this to true. 108const bool kLogLockContentions = false; 109#else 110// Keep this false as lock contention logging is supported only with 111// futex. 112const bool kLogLockContentions = false; 113#endif 114const size_t kContentionLogSize = 4; 115const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 116const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 117 118// Base class for all Mutex implementations 119class BaseMutex { 120 public: 121 const char* GetName() const { 122 return name_; 123 } 124 125 virtual bool IsMutex() const { return false; } 126 virtual bool IsReaderWriterMutex() const { return false; } 127 128 virtual void Dump(std::ostream& os) const = 0; 129 130 static void DumpAll(std::ostream& os); 131 132 protected: 133 friend class ConditionVariable; 134 135 BaseMutex(const char* name, LockLevel level); 136 virtual ~BaseMutex(); 137 void RegisterAsLocked(Thread* self); 138 void RegisterAsUnlocked(Thread* self); 139 void CheckSafeToWait(Thread* self); 140 141 friend class ScopedContentionRecorder; 142 143 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 144 void DumpContention(std::ostream& os) const; 145 146 const LockLevel level_; // Support for lock hierarchy. 147 const char* const name_; 148 149 // A log entry that records contention but makes no guarantee that either tid will be held live. 150 struct ContentionLogEntry { 151 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 152 uint64_t blocked_tid; 153 uint64_t owner_tid; 154 AtomicInteger count; 155 }; 156 struct ContentionLogData { 157 ContentionLogEntry contention_log[kContentionLogSize]; 158 // The next entry in the contention log to be updated. Value ranges from 0 to 159 // kContentionLogSize - 1. 160 AtomicInteger cur_content_log_entry; 161 // Number of times the Mutex has been contended. 162 AtomicInteger contention_count; 163 // Sum of time waited by all contenders in ns. 164 volatile uint64_t wait_time; 165 void AddToWaitTime(uint64_t value); 166 ContentionLogData() : wait_time(0) {} 167 }; 168 ContentionLogData contention_log_data_[kContentionLogDataSize]; 169 170 public: 171 bool HasEverContended() const { 172 if (kLogLockContentions) { 173 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 174 } 175 return false; 176 } 177}; 178 179// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 180// exclusive access to what it guards. A Mutex can be in one of two states: 181// - Free - not owned by any thread, 182// - Exclusive - owned by a single thread. 183// 184// The effect of locking and unlocking operations on the state is: 185// State | ExclusiveLock | ExclusiveUnlock 186// ------------------------------------------- 187// Free | Exclusive | error 188// Exclusive | Block* | Free 189// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 190// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 191std::ostream& operator<<(std::ostream& os, const Mutex& mu); 192class LOCKABLE Mutex : public BaseMutex { 193 public: 194 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 195 ~Mutex(); 196 197 virtual bool IsMutex() const { return true; } 198 199 // Block until mutex is free then acquire exclusive access. 200 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 201 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 202 203 // Returns true if acquires exclusive access, false otherwise. 204 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 205 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 206 207 // Release exclusive access. 208 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 209 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 210 211 // Is the current thread the exclusive holder of the Mutex. 212 bool IsExclusiveHeld(const Thread* self) const; 213 214 // Assert that the Mutex is exclusively held by the current thread. 215 void AssertExclusiveHeld(const Thread* self) { 216 if (kDebugLocking && (gAborting == 0)) { 217 CHECK(IsExclusiveHeld(self)) << *this; 218 } 219 } 220 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 221 222 // Assert that the Mutex is not held by the current thread. 223 void AssertNotHeldExclusive(const Thread* self) { 224 if (kDebugLocking && (gAborting == 0)) { 225 CHECK(!IsExclusiveHeld(self)) << *this; 226 } 227 } 228 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 229 230 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 231 // than the owner. 232 uint64_t GetExclusiveOwnerTid() const; 233 234 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 235 unsigned int GetDepth() const { 236 return recursion_count_; 237 } 238 239 virtual void Dump(std::ostream& os) const; 240 241 private: 242#if ART_USE_FUTEXES 243 // 0 is unheld, 1 is held. 244 AtomicInteger state_; 245 // Exclusive owner. 246 volatile uint64_t exclusive_owner_; 247 // Number of waiting contenders. 248 AtomicInteger num_contenders_; 249#else 250 pthread_mutex_t mutex_; 251 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 252#endif 253 const bool recursive_; // Can the lock be recursively held? 254 unsigned int recursion_count_; 255 friend class ConditionVariable; 256 DISALLOW_COPY_AND_ASSIGN(Mutex); 257}; 258 259// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 260// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 261// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 262// condition variable. A ReaderWriterMutex can be in one of three states: 263// - Free - not owned by any thread, 264// - Exclusive - owned by a single thread, 265// - Shared(n) - shared amongst n threads. 266// 267// The effect of locking and unlocking operations on the state is: 268// 269// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 270// ---------------------------------------------------------------------------- 271// Free | Exclusive | error | SharedLock(1) | error 272// Exclusive | Block | Free | Block | error 273// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 274// * for large values of n the SharedLock may block. 275std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 276class LOCKABLE ReaderWriterMutex : public BaseMutex { 277 public: 278 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 279 ~ReaderWriterMutex(); 280 281 virtual bool IsReaderWriterMutex() const { return true; } 282 283 // Block until ReaderWriterMutex is free then acquire exclusive access. 284 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 285 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 286 287 // Release exclusive access. 288 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 289 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 290 291 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 292 // or false if timeout is reached. 293#if HAVE_TIMED_RWLOCK 294 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 295 EXCLUSIVE_TRYLOCK_FUNCTION(true); 296#endif 297 298 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 299 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 300 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 301 302 // Try to acquire share of ReaderWriterMutex. 303 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 304 305 // Release a share of the access. 306 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 307 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 308 309 // Is the current thread the exclusive holder of the ReaderWriterMutex. 310 bool IsExclusiveHeld(const Thread* self) const; 311 312 // Assert the current thread has exclusive access to the ReaderWriterMutex. 313 void AssertExclusiveHeld(const Thread* self) { 314 if (kDebugLocking && (gAborting == 0)) { 315 CHECK(IsExclusiveHeld(self)) << *this; 316 } 317 } 318 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 319 320 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 321 void AssertNotExclusiveHeld(const Thread* self) { 322 if (kDebugLocking && (gAborting == 0)) { 323 CHECK(!IsExclusiveHeld(self)) << *this; 324 } 325 } 326 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 327 328 // Is the current thread a shared holder of the ReaderWriterMutex. 329 bool IsSharedHeld(const Thread* self) const; 330 331 // Assert the current thread has shared access to the ReaderWriterMutex. 332 void AssertSharedHeld(const Thread* self) { 333 if (kDebugLocking && (gAborting == 0)) { 334 // TODO: we can only assert this well when self != NULL. 335 CHECK(IsSharedHeld(self) || self == NULL) << *this; 336 } 337 } 338 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 339 340 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 341 // mode. 342 void AssertNotHeld(const Thread* self) { 343 if (kDebugLocking && (gAborting == 0)) { 344 CHECK(!IsSharedHeld(self)) << *this; 345 } 346 } 347 348 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 349 // than the owner. 350 uint64_t GetExclusiveOwnerTid() const; 351 352 virtual void Dump(std::ostream& os) const; 353 354 private: 355#if ART_USE_FUTEXES 356 // -1 implies held exclusive, +ve shared held by state_ many owners. 357 AtomicInteger state_; 358 // Exclusive owner. Modification guarded by this mutex. 359 volatile uint64_t exclusive_owner_; 360 // Number of contenders waiting for a reader share. 361 AtomicInteger num_pending_readers_; 362 // Number of contenders waiting to be the writer. 363 AtomicInteger num_pending_writers_; 364#else 365 pthread_rwlock_t rwlock_; 366 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 367#endif 368 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 369}; 370 371// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 372// (Signal) or all at once (Broadcast). 373class ConditionVariable { 374 public: 375 explicit ConditionVariable(const char* name, Mutex& mutex); 376 ~ConditionVariable(); 377 378 void Broadcast(Thread* self); 379 void Signal(Thread* self); 380 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 381 // pointer copy, thereby defeating annotalysis. 382 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 383 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 384 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 385 // when waiting. 386 // TODO: remove this. 387 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 388 389 private: 390 const char* const name_; 391 // The Mutex being used by waiters. It is an error to mix condition variables between different 392 // Mutexes. 393 Mutex& guard_; 394#if ART_USE_FUTEXES 395 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 396 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 397 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 398 // without guard_ held. 399 AtomicInteger sequence_; 400 // Number of threads that have come into to wait, not the length of the waiters on the futex as 401 // waiters may have been requeued onto guard_. Guarded by guard_. 402 volatile int32_t num_waiters_; 403#else 404 pthread_cond_t cond_; 405#endif 406 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 407}; 408 409// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 410// upon destruction. 411class SCOPED_LOCKABLE MutexLock { 412 public: 413 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 414 mu_.ExclusiveLock(self_); 415 } 416 417 ~MutexLock() UNLOCK_FUNCTION() { 418 mu_.ExclusiveUnlock(self_); 419 } 420 421 private: 422 Thread* const self_; 423 Mutex& mu_; 424 DISALLOW_COPY_AND_ASSIGN(MutexLock); 425}; 426// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 427#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 428 429// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 430// construction and releases it upon destruction. 431class SCOPED_LOCKABLE ReaderMutexLock { 432 public: 433 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 434 self_(self), mu_(mu) { 435 mu_.SharedLock(self_); 436 } 437 438 ~ReaderMutexLock() UNLOCK_FUNCTION() { 439 mu_.SharedUnlock(self_); 440 } 441 442 private: 443 Thread* const self_; 444 ReaderWriterMutex& mu_; 445 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 446}; 447// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 448// "ReaderMutexLock mu(lock)". 449#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 450 451// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 452// construction and releases it upon destruction. 453class SCOPED_LOCKABLE WriterMutexLock { 454 public: 455 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 456 self_(self), mu_(mu) { 457 mu_.ExclusiveLock(self_); 458 } 459 460 ~WriterMutexLock() UNLOCK_FUNCTION() { 461 mu_.ExclusiveUnlock(self_); 462 } 463 464 private: 465 Thread* const self_; 466 ReaderWriterMutex& mu_; 467 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 468}; 469// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 470// "WriterMutexLock mu(lock)". 471#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 472 473// Global mutexes corresponding to the levels above. 474class Locks { 475 public: 476 static void Init(); 477 478 // There's a potential race for two threads to try to suspend each other and for both of them 479 // to succeed and get blocked becoming runnable. This lock ensures that only one thread is 480 // requesting suspension of another at any time. As the the thread list suspend thread logic 481 // transitions to runnable, if the current thread were tried to be suspended then this thread 482 // would block holding this lock until it could safely request thread suspension of the other 483 // thread without that thread having a suspension request against this thread. This avoids a 484 // potential deadlock cycle. 485 static Mutex* thread_list_suspend_thread_lock_; 486 487 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 488 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 489 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 490 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 491 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 492 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 493 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 494 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 495 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 496 // chance to acquire the lock. 497 // 498 // Thread suspension: 499 // Shared users | Exclusive user 500 // (holding mutator lock and in kRunnable state) | .. running .. 501 // .. running .. | Request thread suspension by: 502 // .. running .. | - acquiring thread_suspend_count_lock_ 503 // .. running .. | - incrementing Thread::suspend_count_ on 504 // .. running .. | all mutator threads 505 // .. running .. | - releasing thread_suspend_count_lock_ 506 // .. running .. | Block trying to acquire exclusive mutator lock 507 // Poll Thread::suspend_count_ and enter full | .. blocked .. 508 // suspend code. | .. blocked .. 509 // Change state to kSuspended | .. blocked .. 510 // x: Release share on mutator_lock_ | Carry out exclusive access 511 // Acquire thread_suspend_count_lock_ | .. exclusive .. 512 // while Thread::suspend_count_ > 0 | .. exclusive .. 513 // - wait on Thread::resume_cond_ | .. exclusive .. 514 // (releases thread_suspend_count_lock_) | .. exclusive .. 515 // .. waiting .. | Release mutator_lock_ 516 // .. waiting .. | Request thread resumption by: 517 // .. waiting .. | - acquiring thread_suspend_count_lock_ 518 // .. waiting .. | - decrementing Thread::suspend_count_ on 519 // .. waiting .. | all mutator threads 520 // .. waiting .. | - notifying on Thread::resume_cond_ 521 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 522 // Release thread_suspend_count_lock_ | .. running .. 523 // Acquire share on mutator_lock_ | .. running .. 524 // - This could block but the thread still | .. running .. 525 // has a state of kSuspended and so this | .. running .. 526 // isn't an issue. | .. running .. 527 // Acquire thread_suspend_count_lock_ | .. running .. 528 // - we poll here as we're transitioning into | .. running .. 529 // kRunnable and an individual thread suspend | .. running .. 530 // request (e.g for debugging) won't try | .. running .. 531 // to acquire the mutator lock (which would | .. running .. 532 // block as we hold the mutator lock). This | .. running .. 533 // poll ensures that if the suspender thought | .. running .. 534 // we were suspended by incrementing our | .. running .. 535 // Thread::suspend_count_ and then reading | .. running .. 536 // our state we go back to waiting on | .. running .. 537 // Thread::resume_cond_. | .. running .. 538 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 539 // Release thread_suspend_count_lock_ | .. running .. 540 // if can_go_runnable | .. running .. 541 // Change state to kRunnable | .. running .. 542 // else | .. running .. 543 // Goto x | .. running .. 544 // .. running .. | .. running .. 545 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(thread_list_suspend_thread_lock_); 546 547 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 548 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 549 550 // Guards shutdown of the runtime. 551 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 552 553 // Guards background profiler global state. 554 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 555 556 // Guards trace (ie traceview) requests. 557 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 558 559 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 560 // attaching and detaching. 561 static Mutex* thread_list_lock_ ACQUIRED_AFTER(trace_lock_); 562 563 // Guards breakpoints. 564 static Mutex* breakpoint_lock_ ACQUIRED_AFTER(thread_list_lock_); 565 566 // Guards lists of classes within the class linker. 567 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 568 569 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 570 // doesn't try to hold a higher level Mutex. 571 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 572 573 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 574 575 // Guard the allocation/deallocation of thread ids. 576 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 577 578 // Guards modification of the LDT on x86. 579 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 580 581 // Guards intern table. 582 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 583 584 // Have an exclusive aborting thread. 585 static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 586 587 // Allow mutual exclusion when manipulating Thread::suspend_count_. 588 // TODO: Does the trade-off of a per-thread lock make sense? 589 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 590 591 // One unexpected signal at a time lock. 592 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 593 594 // Guards the maps in mem_map. 595 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 596 597 // Have an exclusive logging thread. 598 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 599}; 600 601} // namespace art 602 603#endif // ART_RUNTIME_BASE_MUTEX_H_ 604