mutex.h revision 306db81aba41eb244a4e8299cf58ac18ae9999c7
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 kJdwpObjectRegistryLock, 78 kModifyLdtLock, 79 kAllocatedThreadIdsLock, 80 kMonitorPoolLock, 81 kClassLinkerClassesLock, 82 kBreakpointLock, 83 kMonitorLock, 84 kMonitorListLock, 85 kJniLoadLibraryLock, 86 kThreadListLock, 87 kBreakpointInvokeLock, 88 kAllocTrackerLock, 89 kDeoptimizationLock, 90 kTraceLock, 91 kProfilerLock, 92 kJdwpEventListLock, 93 kJdwpAttachLock, 94 kJdwpStartLock, 95 kRuntimeShutdownLock, 96 kHeapBitmapLock, 97 kMutatorLock, 98 kThreadListSuspendThreadLock, 99 kZygoteCreationLock, 100 101 kLockLevelCount // Must come last. 102}; 103std::ostream& operator<<(std::ostream& os, const LockLevel& rhs); 104 105const bool kDebugLocking = kIsDebugBuild; 106 107// Record Log contention information, dumpable via SIGQUIT. 108#ifdef ART_USE_FUTEXES 109// To enable lock contention logging, set this to true. 110const bool kLogLockContentions = false; 111#else 112// Keep this false as lock contention logging is supported only with 113// futex. 114const bool kLogLockContentions = false; 115#endif 116const size_t kContentionLogSize = 4; 117const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; 118const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; 119 120// Base class for all Mutex implementations 121class BaseMutex { 122 public: 123 const char* GetName() const { 124 return name_; 125 } 126 127 virtual bool IsMutex() const { return false; } 128 virtual bool IsReaderWriterMutex() const { return false; } 129 130 virtual void Dump(std::ostream& os) const = 0; 131 132 static void DumpAll(std::ostream& os); 133 134 protected: 135 friend class ConditionVariable; 136 137 BaseMutex(const char* name, LockLevel level); 138 virtual ~BaseMutex(); 139 void RegisterAsLocked(Thread* self); 140 void RegisterAsUnlocked(Thread* self); 141 void CheckSafeToWait(Thread* self); 142 143 friend class ScopedContentionRecorder; 144 145 void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); 146 void DumpContention(std::ostream& os) const; 147 148 const LockLevel level_; // Support for lock hierarchy. 149 const char* const name_; 150 151 // A log entry that records contention but makes no guarantee that either tid will be held live. 152 struct ContentionLogEntry { 153 ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} 154 uint64_t blocked_tid; 155 uint64_t owner_tid; 156 AtomicInteger count; 157 }; 158 struct ContentionLogData { 159 ContentionLogEntry contention_log[kContentionLogSize]; 160 // The next entry in the contention log to be updated. Value ranges from 0 to 161 // kContentionLogSize - 1. 162 AtomicInteger cur_content_log_entry; 163 // Number of times the Mutex has been contended. 164 AtomicInteger contention_count; 165 // Sum of time waited by all contenders in ns. 166 Atomic<uint64_t> wait_time; 167 void AddToWaitTime(uint64_t value); 168 ContentionLogData() : wait_time(0) {} 169 }; 170 ContentionLogData contention_log_data_[kContentionLogDataSize]; 171 172 public: 173 bool HasEverContended() const { 174 if (kLogLockContentions) { 175 return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0; 176 } 177 return false; 178 } 179}; 180 181// A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain 182// exclusive access to what it guards. A Mutex can be in one of two states: 183// - Free - not owned by any thread, 184// - Exclusive - owned by a single thread. 185// 186// The effect of locking and unlocking operations on the state is: 187// State | ExclusiveLock | ExclusiveUnlock 188// ------------------------------------------- 189// Free | Exclusive | error 190// Exclusive | Block* | Free 191// * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in 192// an error. Being non-reentrant simplifies Waiting on ConditionVariables. 193std::ostream& operator<<(std::ostream& os, const Mutex& mu); 194class LOCKABLE Mutex : public BaseMutex { 195 public: 196 explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); 197 ~Mutex(); 198 199 virtual bool IsMutex() const { return true; } 200 201 // Block until mutex is free then acquire exclusive access. 202 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 203 void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 204 205 // Returns true if acquires exclusive access, false otherwise. 206 bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 207 bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } 208 209 // Release exclusive access. 210 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 211 void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 212 213 // Is the current thread the exclusive holder of the Mutex. 214 bool IsExclusiveHeld(const Thread* self) const; 215 216 // Assert that the Mutex is exclusively held by the current thread. 217 void AssertExclusiveHeld(const Thread* self) { 218 if (kDebugLocking && (gAborting == 0)) { 219 CHECK(IsExclusiveHeld(self)) << *this; 220 } 221 } 222 void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } 223 224 // Assert that the Mutex is not held by the current thread. 225 void AssertNotHeldExclusive(const Thread* self) { 226 if (kDebugLocking && (gAborting == 0)) { 227 CHECK(!IsExclusiveHeld(self)) << *this; 228 } 229 } 230 void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } 231 232 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 233 // than the owner. 234 uint64_t GetExclusiveOwnerTid() const; 235 236 // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. 237 unsigned int GetDepth() const { 238 return recursion_count_; 239 } 240 241 virtual void Dump(std::ostream& os) const; 242 243 private: 244#if ART_USE_FUTEXES 245 // 0 is unheld, 1 is held. 246 AtomicInteger state_; 247 // Exclusive owner. 248 volatile uint64_t exclusive_owner_; 249 // Number of waiting contenders. 250 AtomicInteger num_contenders_; 251#else 252 pthread_mutex_t mutex_; 253 volatile uint64_t exclusive_owner_; // Guarded by mutex_. 254#endif 255 const bool recursive_; // Can the lock be recursively held? 256 unsigned int recursion_count_; 257 friend class ConditionVariable; 258 DISALLOW_COPY_AND_ASSIGN(Mutex); 259}; 260 261// A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. 262// Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) 263// access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a 264// condition variable. A ReaderWriterMutex can be in one of three states: 265// - Free - not owned by any thread, 266// - Exclusive - owned by a single thread, 267// - Shared(n) - shared amongst n threads. 268// 269// The effect of locking and unlocking operations on the state is: 270// 271// State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock 272// ---------------------------------------------------------------------------- 273// Free | Exclusive | error | SharedLock(1) | error 274// Exclusive | Block | Free | Block | error 275// Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free 276// * for large values of n the SharedLock may block. 277std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); 278class LOCKABLE ReaderWriterMutex : public BaseMutex { 279 public: 280 explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); 281 ~ReaderWriterMutex(); 282 283 virtual bool IsReaderWriterMutex() const { return true; } 284 285 // Block until ReaderWriterMutex is free then acquire exclusive access. 286 void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); 287 void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } 288 289 // Release exclusive access. 290 void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); 291 void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } 292 293 // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success 294 // or false if timeout is reached. 295#if HAVE_TIMED_RWLOCK 296 bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) 297 EXCLUSIVE_TRYLOCK_FUNCTION(true); 298#endif 299 300 // Block until ReaderWriterMutex is shared or free then acquire a share on the access. 301 void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; 302 void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } 303 304 // Try to acquire share of ReaderWriterMutex. 305 bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); 306 307 // Release a share of the access. 308 void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; 309 void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } 310 311 // Is the current thread the exclusive holder of the ReaderWriterMutex. 312 bool IsExclusiveHeld(const Thread* self) const; 313 314 // Assert the current thread has exclusive access to the ReaderWriterMutex. 315 void AssertExclusiveHeld(const Thread* self) { 316 if (kDebugLocking && (gAborting == 0)) { 317 CHECK(IsExclusiveHeld(self)) << *this; 318 } 319 } 320 void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } 321 322 // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. 323 void AssertNotExclusiveHeld(const Thread* self) { 324 if (kDebugLocking && (gAborting == 0)) { 325 CHECK(!IsExclusiveHeld(self)) << *this; 326 } 327 } 328 void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } 329 330 // Is the current thread a shared holder of the ReaderWriterMutex. 331 bool IsSharedHeld(const Thread* self) const; 332 333 // Assert the current thread has shared access to the ReaderWriterMutex. 334 void AssertSharedHeld(const Thread* self) { 335 if (kDebugLocking && (gAborting == 0)) { 336 // TODO: we can only assert this well when self != NULL. 337 CHECK(IsSharedHeld(self) || self == NULL) << *this; 338 } 339 } 340 void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } 341 342 // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive 343 // mode. 344 void AssertNotHeld(const Thread* self) { 345 if (kDebugLocking && (gAborting == 0)) { 346 CHECK(!IsSharedHeld(self)) << *this; 347 } 348 } 349 350 // Id associated with exclusive owner. No memory ordering semantics if called from a thread other 351 // than the owner. 352 uint64_t GetExclusiveOwnerTid() const; 353 354 virtual void Dump(std::ostream& os) const; 355 356 private: 357#if ART_USE_FUTEXES 358 // -1 implies held exclusive, +ve shared held by state_ many owners. 359 AtomicInteger state_; 360 // Exclusive owner. Modification guarded by this mutex. 361 volatile uint64_t exclusive_owner_; 362 // Number of contenders waiting for a reader share. 363 AtomicInteger num_pending_readers_; 364 // Number of contenders waiting to be the writer. 365 AtomicInteger num_pending_writers_; 366#else 367 pthread_rwlock_t rwlock_; 368 volatile uint64_t exclusive_owner_; // Guarded by rwlock_. 369#endif 370 DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); 371}; 372 373// ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually 374// (Signal) or all at once (Broadcast). 375class ConditionVariable { 376 public: 377 explicit ConditionVariable(const char* name, Mutex& mutex); 378 ~ConditionVariable(); 379 380 void Broadcast(Thread* self); 381 void Signal(Thread* self); 382 // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their 383 // pointer copy, thereby defeating annotalysis. 384 void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 385 void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; 386 // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held 387 // when waiting. 388 // TODO: remove this. 389 void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; 390 391 private: 392 const char* const name_; 393 // The Mutex being used by waiters. It is an error to mix condition variables between different 394 // Mutexes. 395 Mutex& guard_; 396#if ART_USE_FUTEXES 397 // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up 398 // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ 399 // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait 400 // without guard_ held. 401 AtomicInteger sequence_; 402 // Number of threads that have come into to wait, not the length of the waiters on the futex as 403 // waiters may have been requeued onto guard_. Guarded by guard_. 404 volatile int32_t num_waiters_; 405#else 406 pthread_cond_t cond_; 407#endif 408 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 409}; 410 411// Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it 412// upon destruction. 413class SCOPED_LOCKABLE MutexLock { 414 public: 415 explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { 416 mu_.ExclusiveLock(self_); 417 } 418 419 ~MutexLock() UNLOCK_FUNCTION() { 420 mu_.ExclusiveUnlock(self_); 421 } 422 423 private: 424 Thread* const self_; 425 Mutex& mu_; 426 DISALLOW_COPY_AND_ASSIGN(MutexLock); 427}; 428// Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". 429#define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) 430 431// Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon 432// construction and releases it upon destruction. 433class SCOPED_LOCKABLE ReaderMutexLock { 434 public: 435 explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 436 self_(self), mu_(mu) { 437 mu_.SharedLock(self_); 438 } 439 440 ~ReaderMutexLock() UNLOCK_FUNCTION() { 441 mu_.SharedUnlock(self_); 442 } 443 444 private: 445 Thread* const self_; 446 ReaderWriterMutex& mu_; 447 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 448}; 449// Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of 450// "ReaderMutexLock mu(lock)". 451#define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) 452 453// Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon 454// construction and releases it upon destruction. 455class SCOPED_LOCKABLE WriterMutexLock { 456 public: 457 explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : 458 self_(self), mu_(mu) { 459 mu_.ExclusiveLock(self_); 460 } 461 462 ~WriterMutexLock() UNLOCK_FUNCTION() { 463 mu_.ExclusiveUnlock(self_); 464 } 465 466 private: 467 Thread* const self_; 468 ReaderWriterMutex& mu_; 469 DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); 470}; 471// Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of 472// "WriterMutexLock mu(lock)". 473#define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) 474 475// Global mutexes corresponding to the levels above. 476class Locks { 477 public: 478 static void Init(); 479 480 // There's a potential race for two threads to try to suspend each other and for both of them 481 // to succeed and get blocked becoming runnable. This lock ensures that only one thread is 482 // requesting suspension of another at any time. As the the thread list suspend thread logic 483 // transitions to runnable, if the current thread were tried to be suspended then this thread 484 // would block holding this lock until it could safely request thread suspension of the other 485 // thread without that thread having a suspension request against this thread. This avoids a 486 // potential deadlock cycle. 487 static Mutex* thread_list_suspend_thread_lock_; 488 489 // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block 490 // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds 491 // a share on the mutator_lock_. The garbage collector may also execute with shared access but 492 // at times requires exclusive access to the heap (not to be confused with the heap meta-data 493 // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks 494 // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_ 495 // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition 496 // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on 497 // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector) 498 // chance to acquire the lock. 499 // 500 // Thread suspension: 501 // Shared users | Exclusive user 502 // (holding mutator lock and in kRunnable state) | .. running .. 503 // .. running .. | Request thread suspension by: 504 // .. running .. | - acquiring thread_suspend_count_lock_ 505 // .. running .. | - incrementing Thread::suspend_count_ on 506 // .. running .. | all mutator threads 507 // .. running .. | - releasing thread_suspend_count_lock_ 508 // .. running .. | Block trying to acquire exclusive mutator lock 509 // Poll Thread::suspend_count_ and enter full | .. blocked .. 510 // suspend code. | .. blocked .. 511 // Change state to kSuspended | .. blocked .. 512 // x: Release share on mutator_lock_ | Carry out exclusive access 513 // Acquire thread_suspend_count_lock_ | .. exclusive .. 514 // while Thread::suspend_count_ > 0 | .. exclusive .. 515 // - wait on Thread::resume_cond_ | .. exclusive .. 516 // (releases thread_suspend_count_lock_) | .. exclusive .. 517 // .. waiting .. | Release mutator_lock_ 518 // .. waiting .. | Request thread resumption by: 519 // .. waiting .. | - acquiring thread_suspend_count_lock_ 520 // .. waiting .. | - decrementing Thread::suspend_count_ on 521 // .. waiting .. | all mutator threads 522 // .. waiting .. | - notifying on Thread::resume_cond_ 523 // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_ 524 // Release thread_suspend_count_lock_ | .. running .. 525 // Acquire share on mutator_lock_ | .. running .. 526 // - This could block but the thread still | .. running .. 527 // has a state of kSuspended and so this | .. running .. 528 // isn't an issue. | .. running .. 529 // Acquire thread_suspend_count_lock_ | .. running .. 530 // - we poll here as we're transitioning into | .. running .. 531 // kRunnable and an individual thread suspend | .. running .. 532 // request (e.g for debugging) won't try | .. running .. 533 // to acquire the mutator lock (which would | .. running .. 534 // block as we hold the mutator lock). This | .. running .. 535 // poll ensures that if the suspender thought | .. running .. 536 // we were suspended by incrementing our | .. running .. 537 // Thread::suspend_count_ and then reading | .. running .. 538 // our state we go back to waiting on | .. running .. 539 // Thread::resume_cond_. | .. running .. 540 // can_go_runnable = Thread::suspend_count_ == 0 | .. running .. 541 // Release thread_suspend_count_lock_ | .. running .. 542 // if can_go_runnable | .. running .. 543 // Change state to kRunnable | .. running .. 544 // else | .. running .. 545 // Goto x | .. running .. 546 // .. running .. | .. running .. 547 static ReaderWriterMutex* mutator_lock_ ACQUIRED_AFTER(thread_list_suspend_thread_lock_); 548 549 // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap. 550 static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_); 551 552 // Guards shutdown of the runtime. 553 static Mutex* runtime_shutdown_lock_ ACQUIRED_AFTER(heap_bitmap_lock_); 554 555 // Guards background profiler global state. 556 static Mutex* profiler_lock_ ACQUIRED_AFTER(runtime_shutdown_lock_); 557 558 // Guards trace (ie traceview) requests. 559 static Mutex* trace_lock_ ACQUIRED_AFTER(profiler_lock_); 560 561 // Guards debugger recent allocation records. 562 static Mutex* alloc_tracker_lock_ ACQUIRED_AFTER(trace_lock_); 563 564 // Guards updates to instrumentation to ensure mutual exclusion of 565 // events like deoptimization requests. 566 // TODO: improve name, perhaps instrumentation_update_lock_. 567 static Mutex* deoptimization_lock_ ACQUIRED_AFTER(alloc_tracker_lock_); 568 569 // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads 570 // attaching and detaching. 571 static Mutex* thread_list_lock_ ACQUIRED_AFTER(deoptimization_lock_); 572 573 // Guards maintaining loading library data structures. 574 static Mutex* jni_libraries_lock_ ACQUIRED_AFTER(thread_list_lock_); 575 576 // Guards breakpoints. 577 static ReaderWriterMutex* breakpoint_lock_ ACQUIRED_AFTER(jni_libraries_lock_); 578 579 // Guards lists of classes within the class linker. 580 static ReaderWriterMutex* classlinker_classes_lock_ ACQUIRED_AFTER(breakpoint_lock_); 581 582 // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code 583 // doesn't try to hold a higher level Mutex. 584 #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(Locks::classlinker_classes_lock_) 585 586 static Mutex* allocated_monitor_ids_lock_ ACQUIRED_AFTER(classlinker_classes_lock_); 587 588 // Guard the allocation/deallocation of thread ids. 589 static Mutex* allocated_thread_ids_lock_ ACQUIRED_AFTER(allocated_monitor_ids_lock_); 590 591 // Guards modification of the LDT on x86. 592 static Mutex* modify_ldt_lock_ ACQUIRED_AFTER(allocated_thread_ids_lock_); 593 594 // Guards intern table. 595 static Mutex* intern_table_lock_ ACQUIRED_AFTER(modify_ldt_lock_); 596 597 // Have an exclusive aborting thread. 598 static Mutex* abort_lock_ ACQUIRED_AFTER(intern_table_lock_); 599 600 // Allow mutual exclusion when manipulating Thread::suspend_count_. 601 // TODO: Does the trade-off of a per-thread lock make sense? 602 static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_); 603 604 // One unexpected signal at a time lock. 605 static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_); 606 607 // Guards the maps in mem_map. 608 static Mutex* mem_maps_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 609 610 // Have an exclusive logging thread. 611 static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_); 612}; 613 614} // namespace art 615 616#endif // ART_RUNTIME_BASE_MUTEX_H_ 617