mutex.h revision 59d9d668d4f4286813afe2b4e7c6db839222ce96
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 kOatFileSecondaryLookupLock, 74 kDefaultMutexLevel, 75 kMarkSweepLargeObjectLock, 76 kPinTableLock, 77 kLoadLibraryLock, 78 kJdwpObjectRegistryLock, 79 kModifyLdtLock, 80 kAllocatedThreadIdsLock, 81 kMonitorPoolLock, 82 kClassLinkerClassesLock, 83 kBreakpointLock, 84 kMonitorLock, 85 kMonitorListLock, 86 kThreadListLock, 87 kBreakpointInvokeLock, 88 kDeoptimizationLock, 89 kTraceLock, 90 kProfilerLock, 91 kJdwpEventListLock, 92 kJdwpAttachLock, 93 kJdwpStartLock, 94 kRuntimeShutdownLock, 95 kHeapBitmapLock, 96 kMutatorLock, 97 kThreadListSuspendThreadLock, 98 kZygoteCreationLock, 99 100 kLockLevelCount // Must come last. 101}; 102std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 103 104const bool kDebugLocking = kIsDebugBuild; 105 106// Record Log contention information, dumpable via SIGQUIT. 107#ifdef ART_USE_FUTEXES 108// To enable lock contention logging, set this to true. 109const bool kLogLockContentions = false; 110#else 111// Keep this false as lock contention logging is supported only with 112// futex. 113const bool kLogLockContentions = false; 114#endif 115const size_t kContentionLogSize = 4; 116const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 117const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 118 119// Base class for all Mutex implementations 120class BaseMutex { 121 public: 122 const char* GetName() const { 123 return name_; 124 } 125 126 virtual bool IsMutex() const { return false; } 127 virtual bool IsReaderWriterMutex() const { return false; } 128 129 virtual void Dump(std::ostream& os) const = 0; 130 131 static void DumpAll(std::ostream& os); 132 133 protected: 134 friend class ConditionVariable; 135 136 BaseMutex(const char* name, LockLevel level); 137 virtual ~BaseMutex(); 138 void RegisterAsLocked(Thread* self); 139 void RegisterAsUnlocked(Thread* self); 140 void CheckSafeToWait(Thread* self); 141 142 friend class ScopedContentionRecorder; 143 144 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 145 void DumpContention(std::ostream& os) const; 146 147 const LockLevel level_; // Support for lock hierarchy. 148 const char* const name_; 149 150 // A log entry that records contention but makes no guarantee that either tid will be held live. 151 struct ContentionLogEntry { 152 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 153 uint64_t blocked_tid; 154 uint64_t owner_tid; 155 AtomicInteger count; 156 }; 157 struct ContentionLogData { 158 ContentionLogEntry contention_log[kContentionLogSize]; 159 // The next entry in the contention log to be updated. Value ranges from 0 to 160 // kContentionLogSize - 1. 161 AtomicInteger cur_content_log_entry; 162 // Number of times the Mutex has been contended. 163 AtomicInteger contention_count; 164 // Sum of time waited by all contenders in ns. 165 Atomic<uint64_t> wait_time; 166 void AddToWaitTime(uint64_t value); 167 ContentionLogData() : wait_time(0) {} 168 }; 169 ContentionLogData contention_log_data_[kContentionLogDataSize]; 170 171 public: 172 bool HasEverContended() const { 173 if (kLogLockContentions) { 174 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 175 } 176 return false; 177 } 178}; 179 180// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 181// exclusive access to what it guards. A Mutex can be in one of two states: 182// - Free - not owned by any thread, 183// - Exclusive - owned by a single thread. 184// 185// The effect of locking and unlocking operations on the state is: 186// State | ExclusiveLock | ExclusiveUnlock 187// ------------------------------------------- 188// Free | Exclusive | error 189// Exclusive | Block* | Free 190// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 191// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 192std::ostream& operator<<(std::ostream& os, const Mutex& mu); 193class LOCKABLE Mutex : public BaseMutex { 194 public: 195 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 196 ~Mutex(); 197 198 virtual bool IsMutex() const { return true; } 199 200 // Block until mutex is free then acquire exclusive access. 201 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 202 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 203 204 // Returns true if acquires exclusive access, false otherwise. 205 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 206 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 207 208 // Release exclusive access. 209 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 210 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 211 212 // Is the current thread the exclusive holder of the Mutex. 213 bool IsExclusiveHeld(const Thread* self) const; 214 215 // Assert that the Mutex is exclusively held by the current thread. 216 void AssertExclusiveHeld(const Thread* self) { 217 if (kDebugLocking && (gAborting == 0)) { 218 CHECK(IsExclusiveHeld(self)) << *this; 219 } 220 } 221 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 222 223 // Assert that the Mutex is not held by the current thread. 224 void AssertNotHeldExclusive(const Thread* self) { 225 if (kDebugLocking && (gAborting == 0)) { 226 CHECK(!IsExclusiveHeld(self)) << *this; 227 } 228 } 229 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 230 231 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 232 // than the owner. 233 uint64_t GetExclusiveOwnerTid() const; 234 235 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 236 unsigned int GetDepth() const { 237 return recursion_count_; 238 } 239 240 virtual void Dump(std::ostream& os) const; 241 242 private: 243#if ART_USE_FUTEXES 244 // 0 is unheld, 1 is held. 245 AtomicInteger state_; 246 // Exclusive owner. 247 volatile uint64_t exclusive_owner_; 248 // Number of waiting contenders. 249 AtomicInteger num_contenders_; 250#else 251 pthread_mutex_t mutex_; 252 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 253#endif 254 const bool recursive_; // Can the lock be recursively held? 255 unsigned int recursion_count_; 256 friend class ConditionVariable; 257 DISALLOW_COPY_AND_ASSIGN(Mutex); 258}; 259 260// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 261// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 262// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 263// condition variable. A ReaderWriterMutex can be in one of three states: 264// - Free - not owned by any thread, 265// - Exclusive - owned by a single thread, 266// - Shared(n) - shared amongst n threads. 267// 268// The effect of locking and unlocking operations on the state is: 269// 270// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 271// ---------------------------------------------------------------------------- 272// Free | Exclusive | error | SharedLock(1) | error 273// Exclusive | Block | Free | Block | error 274// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 275// * for large values of n the SharedLock may block. 276std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 277class LOCKABLE ReaderWriterMutex : public BaseMutex { 278 public: 279 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 280 ~ReaderWriterMutex(); 281 282 virtual bool IsReaderWriterMutex() const { return true; } 283 284 // Block until ReaderWriterMutex is free then acquire exclusive access. 285 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 286 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 287 288 // Release exclusive access. 289 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 290 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 291 292 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 293 // or false if timeout is reached. 294#if HAVE_TIMED_RWLOCK 295 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 296 EXCLUSIVE_TRYLOCK_FUNCTION(true); 297#endif 298 299 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 300 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 301 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 302 303 // Try to acquire share of ReaderWriterMutex. 304 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 305 306 // Release a share of the access. 307 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 308 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 309 310 // Is the current thread the exclusive holder of the ReaderWriterMutex. 311 bool IsExclusiveHeld(const Thread* self) const; 312 313 // Assert the current thread has exclusive access to the ReaderWriterMutex. 314 void AssertExclusiveHeld(const Thread* self) { 315 if (kDebugLocking && (gAborting == 0)) { 316 CHECK(IsExclusiveHeld(self)) << *this; 317 } 318 } 319 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 320 321 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 322 void AssertNotExclusiveHeld(const Thread* self) { 323 if (kDebugLocking && (gAborting == 0)) { 324 CHECK(!IsExclusiveHeld(self)) << *this; 325 } 326 } 327 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 328 329 // Is the current thread a shared holder of the ReaderWriterMutex. 330 bool IsSharedHeld(const Thread* self) const; 331 332 // Assert the current thread has shared access to the ReaderWriterMutex. 333 void AssertSharedHeld(const Thread* self) { 334 if (kDebugLocking && (gAborting == 0)) { 335 // TODO: we can only assert this well when self != NULL. 336 CHECK(IsSharedHeld(self) || self == NULL) << *this; 337 } 338 } 339 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 340 341 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 342 // mode. 343 void AssertNotHeld(const Thread* self) { 344 if (kDebugLocking && (gAborting == 0)) { 345 CHECK(!IsSharedHeld(self)) << *this; 346 } 347 } 348 349 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 350 // than the owner. 351 uint64_t GetExclusiveOwnerTid() const; 352 353 virtual void Dump(std::ostream& os) const; 354 355 private: 356#if ART_USE_FUTEXES 357 // -1 implies held exclusive, +ve shared held by state_ many owners. 358 AtomicInteger state_; 359 // Exclusive owner. Modification guarded by this mutex. 360 volatile uint64_t exclusive_owner_; 361 // Number of contenders waiting for a reader share. 362 AtomicInteger num_pending_readers_; 363 // Number of contenders waiting to be the writer. 364 AtomicInteger num_pending_writers_; 365#else 366 pthread_rwlock_t rwlock_; 367 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 368#endif 369 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 370}; 371 372// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 373// (Signal) or all at once (Broadcast). 374class ConditionVariable { 375 public: 376 explicit ConditionVariable(const char* name, Mutex& mutex); 377 ~ConditionVariable(); 378 379 void Broadcast(Thread* self); 380 void Signal(Thread* self); 381 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 382 // pointer copy, thereby defeating annotalysis. 383 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 384 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 385 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 386 // when waiting. 387 // TODO: remove this. 388 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 389 390 private: 391 const char* const name_; 392 // The Mutex being used by waiters. It is an error to mix condition variables between different 393 // Mutexes. 394 Mutex& guard_; 395#if ART_USE_FUTEXES 396 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 397 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 398 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 399 // without guard_ held. 400 AtomicInteger sequence_; 401 // Number of threads that have come into to wait, not the length of the waiters on the futex as 402 // waiters may have been requeued onto guard_. Guarded by guard_. 403 volatile int32_t num_waiters_; 404#else 405 pthread_cond_t cond_; 406#endif 407 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 408}; 409 410// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 411// upon destruction. 412class SCOPED_LOCKABLE MutexLock { 413 public: 414 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 415 mu_.ExclusiveLock(self_); 416 } 417 418 ~MutexLock() UNLOCK_FUNCTION() { 419 mu_.ExclusiveUnlock(self_); 420 } 421 422 private: 423 Thread* const self_; 424 Mutex& mu_; 425 DISALLOW_COPY_AND_ASSIGN(MutexLock); 426}; 427// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 428#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 429 430// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 431// construction and releases it upon destruction. 432class SCOPED_LOCKABLE ReaderMutexLock { 433 public: 434 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 435 self_(self), mu_(mu) { 436 mu_.SharedLock(self_); 437 } 438 439 ~ReaderMutexLock() UNLOCK_FUNCTION() { 440 mu_.SharedUnlock(self_); 441 } 442 443 private: 444 Thread* const self_; 445 ReaderWriterMutex& mu_; 446 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 447}; 448// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 449// "ReaderMutexLock mu(lock)". 450#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 451 452// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 453// construction and releases it upon destruction. 454class SCOPED_LOCKABLE WriterMutexLock { 455 public: 456 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 457 self_(self), mu_(mu) { 458 mu_.ExclusiveLock(self_); 459 } 460 461 ~WriterMutexLock() UNLOCK_FUNCTION() { 462 mu_.ExclusiveUnlock(self_); 463 } 464 465 private: 466 Thread* const self_; 467 ReaderWriterMutex& mu_; 468 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 469}; 470// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 471// "WriterMutexLock mu(lock)". 472#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 473 474// Global mutexes corresponding to the levels above. 475class Locks { 476 public: 477 static void Init(); 478 479 // There's a potential race for two threads to try to suspend each other and for both of them 480 // to succeed and get blocked becoming runnable. This lock ensures that only one thread is 481 // requesting suspension of another at any time. As the the thread list suspend thread logic 482 // transitions to runnable, if the current thread were tried to be suspended then this thread 483 // would block holding this lock until it could safely request thread suspension of the other 484 // thread without that thread having a suspension request against this thread. This avoids a 485 // potential deadlock cycle. 486 static Mutex* thread_list_suspend_thread_lock_; 487 488 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 489 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 490 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 491 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 492 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 493 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 494 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 495 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 496 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 497 // chance to acquire the lock. 498 // 499 // Thread suspension: 500 // Shared users | Exclusive user 501 // (holding mutator lock and in kRunnable state) | .. running .. 502 // .. running .. | Request thread suspension by: 503 // .. running .. | - acquiring thread_suspend_count_lock_ 504 // .. running .. | - incrementing Thread::suspend_count_ on 505 // .. running .. | all mutator threads 506 // .. running .. | - releasing thread_suspend_count_lock_ 507 // .. running .. | Block trying to acquire exclusive mutator lock 508 // Poll Thread::suspend_count_ and enter full | .. blocked .. 509 // suspend code. | .. blocked .. 510 // Change state to kSuspended | .. blocked .. 511 // x: Release share on mutator_lock_ | Carry out exclusive access 512 // Acquire thread_suspend_count_lock_ | .. exclusive .. 513 // while Thread::suspend_count_ > 0 | .. exclusive .. 514 // - wait on Thread::resume_cond_ | .. exclusive .. 515 // (releases thread_suspend_count_lock_) | .. exclusive .. 516 // .. waiting .. | Release mutator_lock_ 517 // .. waiting .. | Request thread resumption by: 518 // .. waiting .. | - acquiring thread_suspend_count_lock_ 519 // .. waiting .. | - decrementing Thread::suspend_count_ on 520 // .. waiting .. | all mutator threads 521 // .. waiting .. | - notifying on Thread::resume_cond_ 522 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 523 // Release thread_suspend_count_lock_ | .. running .. 524 // Acquire share on mutator_lock_ | .. running .. 525 // - This could block but the thread still | .. running .. 526 // has a state of kSuspended and so this | .. running .. 527 // isn't an issue. | .. running .. 528 // Acquire thread_suspend_count_lock_ | .. running .. 529 // - we poll here as we're transitioning into | .. running .. 530 // kRunnable and an individual thread suspend | .. running .. 531 // request (e.g for debugging) won't try | .. running .. 532 // to acquire the mutator lock (which would | .. running .. 533 // block as we hold the mutator lock). This | .. running .. 534 // poll ensures that if the suspender thought | .. running .. 535 // we were suspended by incrementing our | .. running .. 536 // Thread::suspend_count_ and then reading | .. running .. 537 // our state we go back to waiting on | .. running .. 538 // Thread::resume_cond_. | .. running .. 539 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 540 // Release thread_suspend_count_lock_ | .. running .. 541 // if can_go_runnable | .. running .. 542 // Change state to kRunnable | .. running .. 543 // else | .. running .. 544 // Goto x | .. running .. 545 // .. running .. | .. running .. 546 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(thread_list_suspend_thread_lock_); 547 548 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 549 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 550 551 // Guards shutdown of the runtime. 552 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 553 554 // Guards background profiler global state. 555 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 556 557 // Guards trace (ie traceview) requests. 558 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 559 560 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 561 // attaching and detaching. 562 static Mutex* thread_list_lock_ ACQUIRED_AFTER(trace_lock_); 563 564 // Guards breakpoints. 565 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(thread_list_lock_); 566 567 // Guards lists of classes within the class linker. 568 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 569 570 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 571 // doesn't try to hold a higher level Mutex. 572 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 573 574 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 575 576 // Guard the allocation/deallocation of thread ids. 577 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 578 579 // Guards modification of the LDT on x86. 580 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 581 582 // Guards intern table. 583 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 584 585 // Have an exclusive aborting thread. 586 static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 587 588 // Allow mutual exclusion when manipulating Thread::suspend_count_. 589 // TODO: Does the trade-off of a per-thread lock make sense? 590 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 591 592 // One unexpected signal at a time lock. 593 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 594 595 // Guards the maps in mem_map. 596 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 597 598 // Have an exclusive logging thread. 599 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 600}; 601 602} // namespace art 603 604#endif // ART_RUNTIME_BASE_MUTEX_H_ 605