mutex.h revision c5f17732d8144491c642776b6b48c85dfadf4b52
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 kUnexpectedSignalLock, 59 kThreadSuspendCountLock, 60 kAbortLock, 61 kJdwpSocketLock, 62 kRosAllocGlobalLock, 63 kRosAllocBracketLock, 64 kRosAllocBulkFreeLock, 65 kAllocSpaceLock, 66 kReferenceProcessorLock, 67 kDexFileMethodInlinerLock, 68 kDexFileToMethodInlinerMapLock, 69 kMarkSweepMarkStackLock, 70 kTransactionLogLock, 71 kInternTableLock, 72 kMonitorPoolLock, 73 kDefaultMutexLevel, 74 kMarkSweepLargeObjectLock, 75 kPinTableLock, 76 kLoadLibraryLock, 77 kJdwpObjectRegistryLock, 78 kModifyLdtLock, 79 kAllocatedThreadIdsLock, 80 kClassLinkerClassesLock, 81 kBreakpointLock, 82 kMonitorLock, 83 kMonitorListLock, 84 kThreadListLock, 85 kBreakpointInvokeLock, 86 kDeoptimizationLock, 87 kTraceLock, 88 kProfilerLock, 89 kJdwpEventListLock, 90 kJdwpAttachLock, 91 kJdwpStartLock, 92 kRuntimeShutdownLock, 93 kHeapBitmapLock, 94 kMutatorLock, 95 kZygoteCreationLock, 96 97 kLockLevelCount // Must come last. 98}; 99std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 100 101const bool kDebugLocking = kIsDebugBuild; 102 103// Record Log contention information, dumpable via SIGQUIT. 104#ifdef ART_USE_FUTEXES 105// To enable lock contention logging, set this to true. 106const bool kLogLockContentions = false; 107#else 108// Keep this false as lock contention logging is supported only with 109// futex. 110const bool kLogLockContentions = false; 111#endif 112const size_t kContentionLogSize = 4; 113const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 114const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 115 116// Base class for all Mutex implementations 117class BaseMutex { 118 public: 119 const char* GetName() const { 120 return name_; 121 } 122 123 virtual bool IsMutex() const { return false; } 124 virtual bool IsReaderWriterMutex() const { return false; } 125 126 virtual void Dump(std::ostream& os) const = 0; 127 128 static void DumpAll(std::ostream& os); 129 130 protected: 131 friend class ConditionVariable; 132 133 BaseMutex(const char* name, LockLevel level); 134 virtual ~BaseMutex(); 135 void RegisterAsLocked(Thread* self); 136 void RegisterAsUnlocked(Thread* self); 137 void CheckSafeToWait(Thread* self); 138 139 friend class ScopedContentionRecorder; 140 141 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 142 void DumpContention(std::ostream& os) const; 143 144 const LockLevel level_; // Support for lock hierarchy. 145 const char* const name_; 146 147 // A log entry that records contention but makes no guarantee that either tid will be held live. 148 struct ContentionLogEntry { 149 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 150 uint64_t blocked_tid; 151 uint64_t owner_tid; 152 AtomicInteger count; 153 }; 154 struct ContentionLogData { 155 ContentionLogEntry contention_log[kContentionLogSize]; 156 // The next entry in the contention log to be updated. Value ranges from 0 to 157 // kContentionLogSize - 1. 158 AtomicInteger cur_content_log_entry; 159 // Number of times the Mutex has been contended. 160 AtomicInteger contention_count; 161 // Sum of time waited by all contenders in ns. 162 volatile uint64_t wait_time; 163 void AddToWaitTime(uint64_t value); 164 ContentionLogData() : wait_time(0) {} 165 }; 166 ContentionLogData contention_log_data_[kContentionLogDataSize]; 167 168 public: 169 bool HasEverContended() const { 170 if (kLogLockContentions) { 171 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 172 } 173 return false; 174 } 175}; 176 177// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 178// exclusive access to what it guards. A Mutex can be in one of two states: 179// - Free - not owned by any thread, 180// - Exclusive - owned by a single thread. 181// 182// The effect of locking and unlocking operations on the state is: 183// State | ExclusiveLock | ExclusiveUnlock 184// ------------------------------------------- 185// Free | Exclusive | error 186// Exclusive | Block* | Free 187// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 188// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 189std::ostream& operator<<(std::ostream& os, const Mutex& mu); 190class LOCKABLE Mutex : public BaseMutex { 191 public: 192 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 193 ~Mutex(); 194 195 virtual bool IsMutex() const { return true; } 196 197 // Block until mutex is free then acquire exclusive access. 198 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 199 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 200 201 // Returns true if acquires exclusive access, false otherwise. 202 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 203 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 204 205 // Release exclusive access. 206 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 207 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 208 209 // Is the current thread the exclusive holder of the Mutex. 210 bool IsExclusiveHeld(const Thread* self) const; 211 212 // Assert that the Mutex is exclusively held by the current thread. 213 void AssertExclusiveHeld(const Thread* self) { 214 if (kDebugLocking && (gAborting == 0)) { 215 CHECK(IsExclusiveHeld(self)) << *this; 216 } 217 } 218 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 219 220 // Assert that the Mutex is not held by the current thread. 221 void AssertNotHeldExclusive(const Thread* self) { 222 if (kDebugLocking && (gAborting == 0)) { 223 CHECK(!IsExclusiveHeld(self)) << *this; 224 } 225 } 226 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 227 228 // Id associated with exclusive owner. 229 uint64_t GetExclusiveOwnerTid() const; 230 231 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 232 unsigned int GetDepth() const { 233 return recursion_count_; 234 } 235 236 virtual void Dump(std::ostream& os) const; 237 238 private: 239#if ART_USE_FUTEXES 240 // 0 is unheld, 1 is held. 241 volatile int32_t state_; 242 // Exclusive owner. 243 volatile uint64_t exclusive_owner_; 244 // Number of waiting contenders. 245 AtomicInteger num_contenders_; 246#else 247 pthread_mutex_t mutex_; 248 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 249#endif 250 const bool recursive_; // Can the lock be recursively held? 251 unsigned int recursion_count_; 252 friend class ConditionVariable; 253 DISALLOW_COPY_AND_ASSIGN(Mutex); 254}; 255 256// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 257// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 258// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 259// condition variable. A ReaderWriterMutex can be in one of three states: 260// - Free - not owned by any thread, 261// - Exclusive - owned by a single thread, 262// - Shared(n) - shared amongst n threads. 263// 264// The effect of locking and unlocking operations on the state is: 265// 266// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 267// ---------------------------------------------------------------------------- 268// Free | Exclusive | error | SharedLock(1) | error 269// Exclusive | Block | Free | Block | error 270// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 271// * for large values of n the SharedLock may block. 272std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 273class LOCKABLE ReaderWriterMutex : public BaseMutex { 274 public: 275 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 276 ~ReaderWriterMutex(); 277 278 virtual bool IsReaderWriterMutex() const { return true; } 279 280 // Block until ReaderWriterMutex is free then acquire exclusive access. 281 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 282 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 283 284 // Release exclusive access. 285 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 286 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 287 288 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 289 // or false if timeout is reached. 290#if HAVE_TIMED_RWLOCK 291 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 292 EXCLUSIVE_TRYLOCK_FUNCTION(true); 293#endif 294 295 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 296 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 297 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 298 299 // Try to acquire share of ReaderWriterMutex. 300 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 301 302 // Release a share of the access. 303 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 304 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 305 306 // Is the current thread the exclusive holder of the ReaderWriterMutex. 307 bool IsExclusiveHeld(const Thread* self) const; 308 309 // Assert the current thread has exclusive access to the ReaderWriterMutex. 310 void AssertExclusiveHeld(const Thread* self) { 311 if (kDebugLocking && (gAborting == 0)) { 312 CHECK(IsExclusiveHeld(self)) << *this; 313 } 314 } 315 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 316 317 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 318 void AssertNotExclusiveHeld(const Thread* self) { 319 if (kDebugLocking && (gAborting == 0)) { 320 CHECK(!IsExclusiveHeld(self)) << *this; 321 } 322 } 323 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 324 325 // Is the current thread a shared holder of the ReaderWriterMutex. 326 bool IsSharedHeld(const Thread* self) const; 327 328 // Assert the current thread has shared access to the ReaderWriterMutex. 329 void AssertSharedHeld(const Thread* self) { 330 if (kDebugLocking && (gAborting == 0)) { 331 // TODO: we can only assert this well when self != NULL. 332 CHECK(IsSharedHeld(self) || self == NULL) << *this; 333 } 334 } 335 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 336 337 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 338 // mode. 339 void AssertNotHeld(const Thread* self) { 340 if (kDebugLocking && (gAborting == 0)) { 341 CHECK(!IsSharedHeld(self)) << *this; 342 } 343 } 344 345 // Id associated with exclusive owner. 346 uint64_t GetExclusiveOwnerTid() const; 347 348 virtual void Dump(std::ostream& os) const; 349 350 private: 351#if ART_USE_FUTEXES 352 // -1 implies held exclusive, +ve shared held by state_ many owners. 353 volatile int32_t state_; 354 // Exclusive owner. 355 volatile uint64_t exclusive_owner_; 356 // Pending readers. 357 volatile int32_t num_pending_readers_; 358 // Pending writers. 359 AtomicInteger num_pending_writers_; 360#else 361 pthread_rwlock_t rwlock_; 362 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 363#endif 364 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 365}; 366 367// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 368// (Signal) or all at once (Broadcast). 369class ConditionVariable { 370 public: 371 explicit ConditionVariable(const char* name, Mutex& mutex); 372 ~ConditionVariable(); 373 374 void Broadcast(Thread* self); 375 void Signal(Thread* self); 376 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 377 // pointer copy, thereby defeating annotalysis. 378 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 379 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 380 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 381 // when waiting. 382 // TODO: remove this. 383 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 384 385 private: 386 const char* const name_; 387 // The Mutex being used by waiters. It is an error to mix condition variables between different 388 // Mutexes. 389 Mutex& guard_; 390#if ART_USE_FUTEXES 391 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 392 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 393 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 394 // without guard_ held. 395 AtomicInteger sequence_; 396 // Number of threads that have come into to wait, not the length of the waiters on the futex as 397 // waiters may have been requeued onto guard_. Guarded by guard_. 398 volatile int32_t num_waiters_; 399#else 400 pthread_cond_t cond_; 401#endif 402 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 403}; 404 405// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 406// upon destruction. 407class SCOPED_LOCKABLE MutexLock { 408 public: 409 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 410 mu_.ExclusiveLock(self_); 411 } 412 413 ~MutexLock() UNLOCK_FUNCTION() { 414 mu_.ExclusiveUnlock(self_); 415 } 416 417 private: 418 Thread* const self_; 419 Mutex& mu_; 420 DISALLOW_COPY_AND_ASSIGN(MutexLock); 421}; 422// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 423#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 424 425// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 426// construction and releases it upon destruction. 427class SCOPED_LOCKABLE ReaderMutexLock { 428 public: 429 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 430 self_(self), mu_(mu) { 431 mu_.SharedLock(self_); 432 } 433 434 ~ReaderMutexLock() UNLOCK_FUNCTION() { 435 mu_.SharedUnlock(self_); 436 } 437 438 private: 439 Thread* const self_; 440 ReaderWriterMutex& mu_; 441 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 442}; 443// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 444// "ReaderMutexLock mu(lock)". 445#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 446 447// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 448// construction and releases it upon destruction. 449class SCOPED_LOCKABLE WriterMutexLock { 450 public: 451 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 452 self_(self), mu_(mu) { 453 mu_.ExclusiveLock(self_); 454 } 455 456 ~WriterMutexLock() UNLOCK_FUNCTION() { 457 mu_.ExclusiveUnlock(self_); 458 } 459 460 private: 461 Thread* const self_; 462 ReaderWriterMutex& mu_; 463 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 464}; 465// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 466// "WriterMutexLock mu(lock)". 467#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 468 469// Global mutexes corresponding to the levels above. 470class Locks { 471 public: 472 static void Init(); 473 474 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 475 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 476 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 477 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 478 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 479 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 480 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 481 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 482 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 483 // chance to acquire the lock. 484 // 485 // Thread suspension: 486 // Shared users | Exclusive user 487 // (holding mutator lock and in kRunnable state) | .. running .. 488 // .. running .. | Request thread suspension by: 489 // .. running .. | - acquiring thread_suspend_count_lock_ 490 // .. running .. | - incrementing Thread::suspend_count_ on 491 // .. running .. | all mutator threads 492 // .. running .. | - releasing thread_suspend_count_lock_ 493 // .. running .. | Block trying to acquire exclusive mutator lock 494 // Poll Thread::suspend_count_ and enter full | .. blocked .. 495 // suspend code. | .. blocked .. 496 // Change state to kSuspended | .. blocked .. 497 // x: Release share on mutator_lock_ | Carry out exclusive access 498 // Acquire thread_suspend_count_lock_ | .. exclusive .. 499 // while Thread::suspend_count_ > 0 | .. exclusive .. 500 // - wait on Thread::resume_cond_ | .. exclusive .. 501 // (releases thread_suspend_count_lock_) | .. exclusive .. 502 // .. waiting .. | Release mutator_lock_ 503 // .. waiting .. | Request thread resumption by: 504 // .. waiting .. | - acquiring thread_suspend_count_lock_ 505 // .. waiting .. | - decrementing Thread::suspend_count_ on 506 // .. waiting .. | all mutator threads 507 // .. waiting .. | - notifying on Thread::resume_cond_ 508 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 509 // Release thread_suspend_count_lock_ | .. running .. 510 // Acquire share on mutator_lock_ | .. running .. 511 // - This could block but the thread still | .. running .. 512 // has a state of kSuspended and so this | .. running .. 513 // isn't an issue. | .. running .. 514 // Acquire thread_suspend_count_lock_ | .. running .. 515 // - we poll here as we're transitioning into | .. running .. 516 // kRunnable and an individual thread suspend | .. running .. 517 // request (e.g for debugging) won't try | .. running .. 518 // to acquire the mutator lock (which would | .. running .. 519 // block as we hold the mutator lock). This | .. running .. 520 // poll ensures that if the suspender thought | .. running .. 521 // we were suspended by incrementing our | .. running .. 522 // Thread::suspend_count_ and then reading | .. running .. 523 // our state we go back to waiting on | .. running .. 524 // Thread::resume_cond_. | .. running .. 525 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 526 // Release thread_suspend_count_lock_ | .. running .. 527 // if can_go_runnable | .. running .. 528 // Change state to kRunnable | .. running .. 529 // else | .. running .. 530 // Goto x | .. running .. 531 // .. running .. | .. running .. 532 static ReaderWriterMutex* mutator_lock_; 533 534 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 535 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 536 537 // Guards shutdown of the runtime. 538 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 539 540 // Guards background profiler global state. 541 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 542 543 // Guards trace (ie traceview) requests. 544 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 545 546 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 547 // attaching and detaching. 548 static Mutex* thread_list_lock_ ACQUIRED_AFTER(trace_lock_); 549 550 // Guards breakpoints. 551 static Mutex* breakpoint_lock_ ACQUIRED_AFTER(thread_list_lock_); 552 553 // Guards lists of classes within the class linker. 554 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 555 556 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 557 // doesn't try to hold a higher level Mutex. 558 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 559 560 // Guard the allocation/deallocation of thread ids. 561 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 562 563 // Guards modification of the LDT on x86. 564 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 565 566 // Guards intern table. 567 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 568 569 // Have an exclusive aborting thread. 570 static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 571 572 // Allow mutual exclusion when manipulating Thread::suspend_count_. 573 // TODO: Does the trade-off of a per-thread lock make sense? 574 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 575 576 // One unexpected signal at a time lock. 577 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 578 579 // Guards the maps in mem_map. 580 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 581 582 // Have an exclusive logging thread. 583 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 584}; 585 586} // namespace art 587 588#endif // ART_RUNTIME_BASE_MUTEX_H_ 589