mutex.h revision ffddfdf6fec0b9d98a692e27242eecb15af5ead2
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 kUnexpectedSignalLock, 58 kThreadSuspendCountLock, 59 kAbortLock, 60 kJdwpSocketLock, 61 kRosAllocGlobalLock, 62 kRosAllocBracketLock, 63 kRosAllocBulkFreeLock, 64 kAllocSpaceLock, 65 kReferenceProcessorLock, 66 kDexFileMethodInlinerLock, 67 kDexFileToMethodInlinerMapLock, 68 kMarkSweepMarkStackLock, 69 kTransactionLogLock, 70 kInternTableLock, 71 kMonitorPoolLock, 72 kDefaultMutexLevel, 73 kMarkSweepLargeObjectLock, 74 kPinTableLock, 75 kLoadLibraryLock, 76 kJdwpObjectRegistryLock, 77 kModifyLdtLock, 78 kAllocatedThreadIdsLock, 79 kClassLinkerClassesLock, 80 kBreakpointLock, 81 kMonitorLock, 82 kMonitorListLock, 83 kThreadListLock, 84 kBreakpointInvokeLock, 85 kDeoptimizationLock, 86 kTraceLock, 87 kProfilerLock, 88 kJdwpEventListLock, 89 kJdwpAttachLock, 90 kJdwpStartLock, 91 kRuntimeShutdownLock, 92 kHeapBitmapLock, 93 kMutatorLock, 94 kZygoteCreationLock, 95 96 kLockLevelCount // Must come last. 97}; 98std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 99 100const bool kDebugLocking = kIsDebugBuild; 101 102// Record Log contention information, dumpable via SIGQUIT. 103#ifdef ART_USE_FUTEXES 104// To enable lock contention logging, set this to true. 105const bool kLogLockContentions = false; 106#else 107// Keep this false as lock contention logging is supported only with 108// futex. 109const bool kLogLockContentions = false; 110#endif 111const size_t kContentionLogSize = 4; 112const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 113const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 114 115// Base class for all Mutex implementations 116class BaseMutex { 117 public: 118 const char* GetName() const { 119 return name_; 120 } 121 122 virtual bool IsMutex() const { return false; } 123 virtual bool IsReaderWriterMutex() const { return false; } 124 125 virtual void Dump(std::ostream& os) const = 0; 126 127 static void DumpAll(std::ostream& os); 128 129 protected: 130 friend class ConditionVariable; 131 132 BaseMutex(const char* name, LockLevel level); 133 virtual ~BaseMutex(); 134 void RegisterAsLocked(Thread* self); 135 void RegisterAsUnlocked(Thread* self); 136 void CheckSafeToWait(Thread* self); 137 138 friend class ScopedContentionRecorder; 139 140 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 141 void DumpContention(std::ostream& os) const; 142 143 const LockLevel level_; // Support for lock hierarchy. 144 const char* const name_; 145 146 // A log entry that records contention but makes no guarantee that either tid will be held live. 147 struct ContentionLogEntry { 148 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 149 uint64_t blocked_tid; 150 uint64_t owner_tid; 151 AtomicInteger count; 152 }; 153 struct ContentionLogData { 154 ContentionLogEntry contention_log[kContentionLogSize]; 155 // The next entry in the contention log to be updated. Value ranges from 0 to 156 // kContentionLogSize - 1. 157 AtomicInteger cur_content_log_entry; 158 // Number of times the Mutex has been contended. 159 AtomicInteger contention_count; 160 // Sum of time waited by all contenders in ns. 161 volatile uint64_t wait_time; 162 void AddToWaitTime(uint64_t value); 163 ContentionLogData() : wait_time(0) {} 164 }; 165 ContentionLogData contention_log_data_[kContentionLogDataSize]; 166 167 public: 168 bool HasEverContended() const { 169 if (kLogLockContentions) { 170 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 171 } 172 return false; 173 } 174}; 175 176// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 177// exclusive access to what it guards. A Mutex can be in one of two states: 178// - Free - not owned by any thread, 179// - Exclusive - owned by a single thread. 180// 181// The effect of locking and unlocking operations on the state is: 182// State | ExclusiveLock | ExclusiveUnlock 183// ------------------------------------------- 184// Free | Exclusive | error 185// Exclusive | Block* | Free 186// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 187// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 188std::ostream& operator<<(std::ostream& os, const Mutex& mu); 189class LOCKABLE Mutex : public BaseMutex { 190 public: 191 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 192 ~Mutex(); 193 194 virtual bool IsMutex() const { return true; } 195 196 // Block until mutex is free then acquire exclusive access. 197 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 198 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 199 200 // Returns true if acquires exclusive access, false otherwise. 201 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 202 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 203 204 // Release exclusive access. 205 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 206 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 207 208 // Is the current thread the exclusive holder of the Mutex. 209 bool IsExclusiveHeld(const Thread* self) const; 210 211 // Assert that the Mutex is exclusively held by the current thread. 212 void AssertExclusiveHeld(const Thread* self) { 213 if (kDebugLocking && (gAborting == 0)) { 214 CHECK(IsExclusiveHeld(self)) << *this; 215 } 216 } 217 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 218 219 // Assert that the Mutex is not held by the current thread. 220 void AssertNotHeldExclusive(const Thread* self) { 221 if (kDebugLocking && (gAborting == 0)) { 222 CHECK(!IsExclusiveHeld(self)) << *this; 223 } 224 } 225 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 226 227 // Id associated with exclusive owner. 228 uint64_t GetExclusiveOwnerTid() const; 229 230 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 231 unsigned int GetDepth() const { 232 return recursion_count_; 233 } 234 235 virtual void Dump(std::ostream& os) const; 236 237 private: 238#if ART_USE_FUTEXES 239 // 0 is unheld, 1 is held. 240 volatile int32_t state_; 241 // Exclusive owner. 242 volatile uint64_t exclusive_owner_; 243 // Number of waiting contenders. 244 AtomicInteger num_contenders_; 245#else 246 pthread_mutex_t mutex_; 247#endif 248 const bool recursive_; // Can the lock be recursively held? 249 unsigned int recursion_count_; 250 friend class ConditionVariable; 251 DISALLOW_COPY_AND_ASSIGN(Mutex); 252}; 253 254// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 255// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 256// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 257// condition variable. A ReaderWriterMutex can be in one of three states: 258// - Free - not owned by any thread, 259// - Exclusive - owned by a single thread, 260// - Shared(n) - shared amongst n threads. 261// 262// The effect of locking and unlocking operations on the state is: 263// 264// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 265// ---------------------------------------------------------------------------- 266// Free | Exclusive | error | SharedLock(1) | error 267// Exclusive | Block | Free | Block | error 268// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 269// * for large values of n the SharedLock may block. 270std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 271class LOCKABLE ReaderWriterMutex : public BaseMutex { 272 public: 273 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 274 ~ReaderWriterMutex(); 275 276 virtual bool IsReaderWriterMutex() const { return true; } 277 278 // Block until ReaderWriterMutex is free then acquire exclusive access. 279 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 280 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 281 282 // Release exclusive access. 283 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 284 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 285 286 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 287 // or false if timeout is reached. 288#if HAVE_TIMED_RWLOCK 289 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 290 EXCLUSIVE_TRYLOCK_FUNCTION(true); 291#endif 292 293 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 294 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 295 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 296 297 // Try to acquire share of ReaderWriterMutex. 298 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 299 300 // Release a share of the access. 301 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 302 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 303 304 // Is the current thread the exclusive holder of the ReaderWriterMutex. 305 bool IsExclusiveHeld(const Thread* self) const; 306 307 // Assert the current thread has exclusive access to the ReaderWriterMutex. 308 void AssertExclusiveHeld(const Thread* self) { 309 if (kDebugLocking && (gAborting == 0)) { 310 CHECK(IsExclusiveHeld(self)) << *this; 311 } 312 } 313 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 314 315 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 316 void AssertNotExclusiveHeld(const Thread* self) { 317 if (kDebugLocking && (gAborting == 0)) { 318 CHECK(!IsExclusiveHeld(self)) << *this; 319 } 320 } 321 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 322 323 // Is the current thread a shared holder of the ReaderWriterMutex. 324 bool IsSharedHeld(const Thread* self) const; 325 326 // Assert the current thread has shared access to the ReaderWriterMutex. 327 void AssertSharedHeld(const Thread* self) { 328 if (kDebugLocking && (gAborting == 0)) { 329 // TODO: we can only assert this well when self != NULL. 330 CHECK(IsSharedHeld(self) || self == NULL) << *this; 331 } 332 } 333 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 334 335 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 336 // mode. 337 void AssertNotHeld(const Thread* self) { 338 if (kDebugLocking && (gAborting == 0)) { 339 CHECK(!IsSharedHeld(self)) << *this; 340 } 341 } 342 343 // Id associated with exclusive owner. 344 uint64_t GetExclusiveOwnerTid() const; 345 346 virtual void Dump(std::ostream& os) const; 347 348 private: 349#if ART_USE_FUTEXES 350 // -1 implies held exclusive, +ve shared held by state_ many owners. 351 volatile int32_t state_; 352 // Exclusive owner. 353 volatile uint64_t exclusive_owner_; 354 // Pending readers. 355 volatile int32_t num_pending_readers_; 356 // Pending writers. 357 AtomicInteger num_pending_writers_; 358#else 359 pthread_rwlock_t rwlock_; 360#endif 361 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 362}; 363 364// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 365// (Signal) or all at once (Broadcast). 366class ConditionVariable { 367 public: 368 explicit ConditionVariable(const char* name, Mutex& mutex); 369 ~ConditionVariable(); 370 371 void Broadcast(Thread* self); 372 void Signal(Thread* self); 373 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 374 // pointer copy, thereby defeating annotalysis. 375 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 376 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 377 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 378 // when waiting. 379 // TODO: remove this. 380 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 381 382 private: 383 const char* const name_; 384 // The Mutex being used by waiters. It is an error to mix condition variables between different 385 // Mutexes. 386 Mutex& guard_; 387#if ART_USE_FUTEXES 388 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 389 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 390 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 391 // without guard_ held. 392 AtomicInteger sequence_; 393 // Number of threads that have come into to wait, not the length of the waiters on the futex as 394 // waiters may have been requeued onto guard_. Guarded by guard_. 395 volatile int32_t num_waiters_; 396#else 397 pthread_cond_t cond_; 398#endif 399 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 400}; 401 402// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 403// upon destruction. 404class SCOPED_LOCKABLE MutexLock { 405 public: 406 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 407 mu_.ExclusiveLock(self_); 408 } 409 410 ~MutexLock() UNLOCK_FUNCTION() { 411 mu_.ExclusiveUnlock(self_); 412 } 413 414 private: 415 Thread* const self_; 416 Mutex& mu_; 417 DISALLOW_COPY_AND_ASSIGN(MutexLock); 418}; 419// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 420#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 421 422// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 423// construction and releases it upon destruction. 424class SCOPED_LOCKABLE ReaderMutexLock { 425 public: 426 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 427 self_(self), mu_(mu) { 428 mu_.SharedLock(self_); 429 } 430 431 ~ReaderMutexLock() UNLOCK_FUNCTION() { 432 mu_.SharedUnlock(self_); 433 } 434 435 private: 436 Thread* const self_; 437 ReaderWriterMutex& mu_; 438 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 439}; 440// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 441// "ReaderMutexLock mu(lock)". 442#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 443 444// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 445// construction and releases it upon destruction. 446class SCOPED_LOCKABLE WriterMutexLock { 447 public: 448 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 449 self_(self), mu_(mu) { 450 mu_.ExclusiveLock(self_); 451 } 452 453 ~WriterMutexLock() UNLOCK_FUNCTION() { 454 mu_.ExclusiveUnlock(self_); 455 } 456 457 private: 458 Thread* const self_; 459 ReaderWriterMutex& mu_; 460 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 461}; 462// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 463// "WriterMutexLock mu(lock)". 464#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 465 466// Global mutexes corresponding to the levels above. 467class Locks { 468 public: 469 static void Init(); 470 471 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 472 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 473 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 474 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 475 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 476 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 477 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 478 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 479 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 480 // chance to acquire the lock. 481 // 482 // Thread suspension: 483 // Shared users | Exclusive user 484 // (holding mutator lock and in kRunnable state) | .. running .. 485 // .. running .. | Request thread suspension by: 486 // .. running .. | - acquiring thread_suspend_count_lock_ 487 // .. running .. | - incrementing Thread::suspend_count_ on 488 // .. running .. | all mutator threads 489 // .. running .. | - releasing thread_suspend_count_lock_ 490 // .. running .. | Block trying to acquire exclusive mutator lock 491 // Poll Thread::suspend_count_ and enter full | .. blocked .. 492 // suspend code. | .. blocked .. 493 // Change state to kSuspended | .. blocked .. 494 // x: Release share on mutator_lock_ | Carry out exclusive access 495 // Acquire thread_suspend_count_lock_ | .. exclusive .. 496 // while Thread::suspend_count_ > 0 | .. exclusive .. 497 // - wait on Thread::resume_cond_ | .. exclusive .. 498 // (releases thread_suspend_count_lock_) | .. exclusive .. 499 // .. waiting .. | Release mutator_lock_ 500 // .. waiting .. | Request thread resumption by: 501 // .. waiting .. | - acquiring thread_suspend_count_lock_ 502 // .. waiting .. | - decrementing Thread::suspend_count_ on 503 // .. waiting .. | all mutator threads 504 // .. waiting .. | - notifying on Thread::resume_cond_ 505 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 506 // Release thread_suspend_count_lock_ | .. running .. 507 // Acquire share on mutator_lock_ | .. running .. 508 // - This could block but the thread still | .. running .. 509 // has a state of kSuspended and so this | .. running .. 510 // isn't an issue. | .. running .. 511 // Acquire thread_suspend_count_lock_ | .. running .. 512 // - we poll here as we're transitioning into | .. running .. 513 // kRunnable and an individual thread suspend | .. running .. 514 // request (e.g for debugging) won't try | .. running .. 515 // to acquire the mutator lock (which would | .. running .. 516 // block as we hold the mutator lock). This | .. running .. 517 // poll ensures that if the suspender thought | .. running .. 518 // we were suspended by incrementing our | .. running .. 519 // Thread::suspend_count_ and then reading | .. running .. 520 // our state we go back to waiting on | .. running .. 521 // Thread::resume_cond_. | .. running .. 522 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 523 // Release thread_suspend_count_lock_ | .. running .. 524 // if can_go_runnable | .. running .. 525 // Change state to kRunnable | .. running .. 526 // else | .. running .. 527 // Goto x | .. running .. 528 // .. running .. | .. running .. 529 static ReaderWriterMutex* mutator_lock_; 530 531 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 532 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 533 534 // Guards shutdown of the runtime. 535 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 536 537 // Guards background profiler global state. 538 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 539 540 // Guards trace (ie traceview) requests. 541 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 542 543 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 544 // attaching and detaching. 545 static Mutex* thread_list_lock_ ACQUIRED_AFTER(trace_lock_); 546 547 // Guards breakpoints. 548 static Mutex* breakpoint_lock_ ACQUIRED_AFTER(thread_list_lock_); 549 550 // Guards lists of classes within the class linker. 551 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 552 553 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 554 // doesn't try to hold a higher level Mutex. 555 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 556 557 // Guard the allocation/deallocation of thread ids. 558 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 559 560 // Guards modification of the LDT on x86. 561 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 562 563 // Guards intern table. 564 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 565 566 // Have an exclusive aborting thread. 567 static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 568 569 // Allow mutual exclusion when manipulating Thread::suspend_count_. 570 // TODO: Does the trade-off of a per-thread lock make sense? 571 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 572 573 // One unexpected signal at a time lock. 574 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 575 576 // Have an exclusive logging thread. 577 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 578}; 579 580} // namespace art 581 582#endif // ART_RUNTIME_BASE_MUTEX_H_ 583