mutex.h revision 7de77dd4f2d3cbb0615ee001589eb99ae82c3dcc
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 kMonitorPoolLock, 74 kDefaultMutexLevel, 75 kMarkSweepLargeObjectLock, 76 kPinTableLock, 77 kLoadLibraryLock, 78 kJdwpObjectRegistryLock, 79 kModifyLdtLock, 80 kAllocatedThreadIdsLock, 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 kZygoteCreationLock, 97 98 kLockLevelCount // Must come last. 99}; 100std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 101 102const bool kDebugLocking = kIsDebugBuild; 103 104// Record Log contention information, dumpable via SIGQUIT. 105#ifdef ART_USE_FUTEXES 106// To enable lock contention logging, set this to true. 107const bool kLogLockContentions = false; 108#else 109// Keep this false as lock contention logging is supported only with 110// futex. 111const bool kLogLockContentions = false; 112#endif 113const size_t kContentionLogSize = 4; 114const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 115const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 116 117// Base class for all Mutex implementations 118class BaseMutex { 119 public: 120 const char* GetName() const { 121 return name_; 122 } 123 124 virtual bool IsMutex() const { return false; } 125 virtual bool IsReaderWriterMutex() const { return false; } 126 127 virtual void Dump(std::ostream& os) const = 0; 128 129 static void DumpAll(std::ostream& os); 130 131 protected: 132 friend class ConditionVariable; 133 134 BaseMutex(const char* name, LockLevel level); 135 virtual ~BaseMutex(); 136 void RegisterAsLocked(Thread* self); 137 void RegisterAsUnlocked(Thread* self); 138 void CheckSafeToWait(Thread* self); 139 140 friend class ScopedContentionRecorder; 141 142 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 143 void DumpContention(std::ostream& os) const; 144 145 const LockLevel level_; // Support for lock hierarchy. 146 const char* const name_; 147 148 // A log entry that records contention but makes no guarantee that either tid will be held live. 149 struct ContentionLogEntry { 150 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 151 uint64_t blocked_tid; 152 uint64_t owner_tid; 153 AtomicInteger count; 154 }; 155 struct ContentionLogData { 156 ContentionLogEntry contention_log[kContentionLogSize]; 157 // The next entry in the contention log to be updated. Value ranges from 0 to 158 // kContentionLogSize - 1. 159 AtomicInteger cur_content_log_entry; 160 // Number of times the Mutex has been contended. 161 AtomicInteger contention_count; 162 // Sum of time waited by all contenders in ns. 163 volatile uint64_t wait_time; 164 void AddToWaitTime(uint64_t value); 165 ContentionLogData() : wait_time(0) {} 166 }; 167 ContentionLogData contention_log_data_[kContentionLogDataSize]; 168 169 public: 170 bool HasEverContended() const { 171 if (kLogLockContentions) { 172 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 173 } 174 return false; 175 } 176}; 177 178// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 179// exclusive access to what it guards. A Mutex can be in one of two states: 180// - Free - not owned by any thread, 181// - Exclusive - owned by a single thread. 182// 183// The effect of locking and unlocking operations on the state is: 184// State | ExclusiveLock | ExclusiveUnlock 185// ------------------------------------------- 186// Free | Exclusive | error 187// Exclusive | Block* | Free 188// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 189// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 190std::ostream& operator<<(std::ostream& os, const Mutex& mu); 191class LOCKABLE Mutex : public BaseMutex { 192 public: 193 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 194 ~Mutex(); 195 196 virtual bool IsMutex() const { return true; } 197 198 // Block until mutex is free then acquire exclusive access. 199 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 200 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 201 202 // Returns true if acquires exclusive access, false otherwise. 203 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 204 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 205 206 // Release exclusive access. 207 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 208 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 209 210 // Is the current thread the exclusive holder of the Mutex. 211 bool IsExclusiveHeld(const Thread* self) const; 212 213 // Assert that the Mutex is exclusively held by the current thread. 214 void AssertExclusiveHeld(const Thread* self) { 215 if (kDebugLocking && (gAborting == 0)) { 216 CHECK(IsExclusiveHeld(self)) << *this; 217 } 218 } 219 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 220 221 // Assert that the Mutex is not held by the current thread. 222 void AssertNotHeldExclusive(const Thread* self) { 223 if (kDebugLocking && (gAborting == 0)) { 224 CHECK(!IsExclusiveHeld(self)) << *this; 225 } 226 } 227 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 228 229 // Id associated with exclusive owner. 230 uint64_t GetExclusiveOwnerTid() const; 231 232 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 233 unsigned int GetDepth() const { 234 return recursion_count_; 235 } 236 237 virtual void Dump(std::ostream& os) const; 238 239 private: 240#if ART_USE_FUTEXES 241 // 0 is unheld, 1 is held. 242 volatile int32_t state_; 243 // Exclusive owner. 244 volatile uint64_t exclusive_owner_; 245 // Number of waiting contenders. 246 AtomicInteger num_contenders_; 247#else 248 pthread_mutex_t mutex_; 249 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 250#endif 251 const bool recursive_; // Can the lock be recursively held? 252 unsigned int recursion_count_; 253 friend class ConditionVariable; 254 DISALLOW_COPY_AND_ASSIGN(Mutex); 255}; 256 257// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 258// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 259// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 260// condition variable. A ReaderWriterMutex can be in one of three states: 261// - Free - not owned by any thread, 262// - Exclusive - owned by a single thread, 263// - Shared(n) - shared amongst n threads. 264// 265// The effect of locking and unlocking operations on the state is: 266// 267// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 268// ---------------------------------------------------------------------------- 269// Free | Exclusive | error | SharedLock(1) | error 270// Exclusive | Block | Free | Block | error 271// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 272// * for large values of n the SharedLock may block. 273std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 274class LOCKABLE ReaderWriterMutex : public BaseMutex { 275 public: 276 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 277 ~ReaderWriterMutex(); 278 279 virtual bool IsReaderWriterMutex() const { return true; } 280 281 // Block until ReaderWriterMutex is free then acquire exclusive access. 282 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 283 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 284 285 // Release exclusive access. 286 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 287 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 288 289 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 290 // or false if timeout is reached. 291#if HAVE_TIMED_RWLOCK 292 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 293 EXCLUSIVE_TRYLOCK_FUNCTION(true); 294#endif 295 296 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 297 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 298 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 299 300 // Try to acquire share of ReaderWriterMutex. 301 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 302 303 // Release a share of the access. 304 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 305 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 306 307 // Is the current thread the exclusive holder of the ReaderWriterMutex. 308 bool IsExclusiveHeld(const Thread* self) const; 309 310 // Assert the current thread has exclusive access to the ReaderWriterMutex. 311 void AssertExclusiveHeld(const Thread* self) { 312 if (kDebugLocking && (gAborting == 0)) { 313 CHECK(IsExclusiveHeld(self)) << *this; 314 } 315 } 316 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 317 318 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 319 void AssertNotExclusiveHeld(const Thread* self) { 320 if (kDebugLocking && (gAborting == 0)) { 321 CHECK(!IsExclusiveHeld(self)) << *this; 322 } 323 } 324 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 325 326 // Is the current thread a shared holder of the ReaderWriterMutex. 327 bool IsSharedHeld(const Thread* self) const; 328 329 // Assert the current thread has shared access to the ReaderWriterMutex. 330 void AssertSharedHeld(const Thread* self) { 331 if (kDebugLocking && (gAborting == 0)) { 332 // TODO: we can only assert this well when self != NULL. 333 CHECK(IsSharedHeld(self) || self == NULL) << *this; 334 } 335 } 336 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 337 338 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 339 // mode. 340 void AssertNotHeld(const Thread* self) { 341 if (kDebugLocking && (gAborting == 0)) { 342 CHECK(!IsSharedHeld(self)) << *this; 343 } 344 } 345 346 // Id associated with exclusive owner. 347 uint64_t GetExclusiveOwnerTid() const; 348 349 virtual void Dump(std::ostream& os) const; 350 351 private: 352#if ART_USE_FUTEXES 353 // -1 implies held exclusive, +ve shared held by state_ many owners. 354 volatile int32_t state_; 355 // Exclusive owner. 356 volatile uint64_t exclusive_owner_; 357 // Pending readers. 358 volatile int32_t num_pending_readers_; 359 // Pending writers. 360 AtomicInteger num_pending_writers_; 361#else 362 pthread_rwlock_t rwlock_; 363 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 364#endif 365 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 366}; 367 368// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 369// (Signal) or all at once (Broadcast). 370class ConditionVariable { 371 public: 372 explicit ConditionVariable(const char* name, Mutex& mutex); 373 ~ConditionVariable(); 374 375 void Broadcast(Thread* self); 376 void Signal(Thread* self); 377 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 378 // pointer copy, thereby defeating annotalysis. 379 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 380 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 381 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 382 // when waiting. 383 // TODO: remove this. 384 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 385 386 private: 387 const char* const name_; 388 // The Mutex being used by waiters. It is an error to mix condition variables between different 389 // Mutexes. 390 Mutex& guard_; 391#if ART_USE_FUTEXES 392 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 393 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 394 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 395 // without guard_ held. 396 AtomicInteger sequence_; 397 // Number of threads that have come into to wait, not the length of the waiters on the futex as 398 // waiters may have been requeued onto guard_. Guarded by guard_. 399 volatile int32_t num_waiters_; 400#else 401 pthread_cond_t cond_; 402#endif 403 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 404}; 405 406// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 407// upon destruction. 408class SCOPED_LOCKABLE MutexLock { 409 public: 410 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 411 mu_.ExclusiveLock(self_); 412 } 413 414 ~MutexLock() UNLOCK_FUNCTION() { 415 mu_.ExclusiveUnlock(self_); 416 } 417 418 private: 419 Thread* const self_; 420 Mutex& mu_; 421 DISALLOW_COPY_AND_ASSIGN(MutexLock); 422}; 423// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 424#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 425 426// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 427// construction and releases it upon destruction. 428class SCOPED_LOCKABLE ReaderMutexLock { 429 public: 430 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 431 self_(self), mu_(mu) { 432 mu_.SharedLock(self_); 433 } 434 435 ~ReaderMutexLock() UNLOCK_FUNCTION() { 436 mu_.SharedUnlock(self_); 437 } 438 439 private: 440 Thread* const self_; 441 ReaderWriterMutex& mu_; 442 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 443}; 444// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 445// "ReaderMutexLock mu(lock)". 446#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 447 448// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 449// construction and releases it upon destruction. 450class SCOPED_LOCKABLE WriterMutexLock { 451 public: 452 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 453 self_(self), mu_(mu) { 454 mu_.ExclusiveLock(self_); 455 } 456 457 ~WriterMutexLock() UNLOCK_FUNCTION() { 458 mu_.ExclusiveUnlock(self_); 459 } 460 461 private: 462 Thread* const self_; 463 ReaderWriterMutex& mu_; 464 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 465}; 466// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 467// "WriterMutexLock mu(lock)". 468#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 469 470// Global mutexes corresponding to the levels above. 471class Locks { 472 public: 473 static void Init(); 474 475 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 476 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 477 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 478 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 479 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 480 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 481 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 482 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 483 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 484 // chance to acquire the lock. 485 // 486 // Thread suspension: 487 // Shared users | Exclusive user 488 // (holding mutator lock and in kRunnable state) | .. running .. 489 // .. running .. | Request thread suspension by: 490 // .. running .. | - acquiring thread_suspend_count_lock_ 491 // .. running .. | - incrementing Thread::suspend_count_ on 492 // .. running .. | all mutator threads 493 // .. running .. | - releasing thread_suspend_count_lock_ 494 // .. running .. | Block trying to acquire exclusive mutator lock 495 // Poll Thread::suspend_count_ and enter full | .. blocked .. 496 // suspend code. | .. blocked .. 497 // Change state to kSuspended | .. blocked .. 498 // x: Release share on mutator_lock_ | Carry out exclusive access 499 // Acquire thread_suspend_count_lock_ | .. exclusive .. 500 // while Thread::suspend_count_ > 0 | .. exclusive .. 501 // - wait on Thread::resume_cond_ | .. exclusive .. 502 // (releases thread_suspend_count_lock_) | .. exclusive .. 503 // .. waiting .. | Release mutator_lock_ 504 // .. waiting .. | Request thread resumption by: 505 // .. waiting .. | - acquiring thread_suspend_count_lock_ 506 // .. waiting .. | - decrementing Thread::suspend_count_ on 507 // .. waiting .. | all mutator threads 508 // .. waiting .. | - notifying on Thread::resume_cond_ 509 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 510 // Release thread_suspend_count_lock_ | .. running .. 511 // Acquire share on mutator_lock_ | .. running .. 512 // - This could block but the thread still | .. running .. 513 // has a state of kSuspended and so this | .. running .. 514 // isn't an issue. | .. running .. 515 // Acquire thread_suspend_count_lock_ | .. running .. 516 // - we poll here as we're transitioning into | .. running .. 517 // kRunnable and an individual thread suspend | .. running .. 518 // request (e.g for debugging) won't try | .. running .. 519 // to acquire the mutator lock (which would | .. running .. 520 // block as we hold the mutator lock). This | .. running .. 521 // poll ensures that if the suspender thought | .. running .. 522 // we were suspended by incrementing our | .. running .. 523 // Thread::suspend_count_ and then reading | .. running .. 524 // our state we go back to waiting on | .. running .. 525 // Thread::resume_cond_. | .. running .. 526 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 527 // Release thread_suspend_count_lock_ | .. running .. 528 // if can_go_runnable | .. running .. 529 // Change state to kRunnable | .. running .. 530 // else | .. running .. 531 // Goto x | .. running .. 532 // .. running .. | .. running .. 533 static ReaderWriterMutex* mutator_lock_; 534 535 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 536 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 537 538 // Guards shutdown of the runtime. 539 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 540 541 // Guards background profiler global state. 542 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 543 544 // Guards trace (ie traceview) requests. 545 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 546 547 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 548 // attaching and detaching. 549 static Mutex* thread_list_lock_ ACQUIRED_AFTER(trace_lock_); 550 551 // Guards breakpoints. 552 static Mutex* breakpoint_lock_ ACQUIRED_AFTER(thread_list_lock_); 553 554 // Guards lists of classes within the class linker. 555 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 556 557 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 558 // doesn't try to hold a higher level Mutex. 559 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 560 561 // Guard the allocation/deallocation of thread ids. 562 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 563 564 // Guards modification of the LDT on x86. 565 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 566 567 // Guards intern table. 568 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 569 570 // Have an exclusive aborting thread. 571 static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 572 573 // Allow mutual exclusion when manipulating Thread::suspend_count_. 574 // TODO: Does the trade-off of a per-thread lock make sense? 575 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 576 577 // One unexpected signal at a time lock. 578 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 579 580 // Guards the maps in mem_map. 581 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 582 583 // Have an exclusive logging thread. 584 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 585}; 586 587} // namespace art 588 589#endif // ART_RUNTIME_BASE_MUTEX_H_ 590