| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ART_RUNTIME_BASE_MUTEX_H_ |
| #define ART_RUNTIME_BASE_MUTEX_H_ |
| |
| #include <pthread.h> |
| #include <stdint.h> |
| |
| #include <iosfwd> |
| #include <string> |
| |
| #include "atomic_integer.h" |
| #include "base/logging.h" |
| #include "base/macros.h" |
| #include "globals.h" |
| #include "locks.h" |
| |
| #if defined(__APPLE__) |
| #define ART_USE_FUTEXES 0 |
| #else |
| #define ART_USE_FUTEXES !defined(__mips__) |
| #endif |
| |
| // Currently Darwin doesn't support locks with timeouts. |
| #if !defined(__APPLE__) |
| #define HAVE_TIMED_RWLOCK 1 |
| #else |
| #define HAVE_TIMED_RWLOCK 0 |
| #endif |
| |
| namespace art { |
| |
| class ScopedContentionRecorder; |
| class Thread; |
| |
| const bool kDebugLocking = kIsDebugBuild; |
| |
| // Record Log contention information, dumpable via SIGQUIT. |
| #ifdef ART_USE_FUTEXES |
| // To enable lock contention logging, flip this to true. |
| const bool kLogLockContentions = false; |
| #else |
| // Keep this false as lock contention logging is supported only with |
| // futex. |
| const bool kLogLockContentions = false; |
| #endif |
| const size_t kContentionLogSize = 64; |
| const size_t kContentionLogDataSize = kLogLockContentions ? 1 : 0; |
| const size_t kAllMutexDataSize = kLogLockContentions ? 1 : 0; |
| |
| // Base class for all Mutex implementations |
| class BaseMutex { |
| public: |
| const char* GetName() const { |
| return name_; |
| } |
| |
| virtual bool IsMutex() const { return false; } |
| virtual bool IsReaderWriterMutex() const { return false; } |
| |
| virtual void Dump(std::ostream& os) const = 0; |
| |
| static void DumpAll(std::ostream& os); |
| |
| protected: |
| friend class ConditionVariable; |
| |
| BaseMutex(const char* name, LockLevel level); |
| virtual ~BaseMutex(); |
| void RegisterAsLocked(Thread* self); |
| void RegisterAsUnlocked(Thread* self); |
| void CheckSafeToWait(Thread* self); |
| |
| friend class ScopedContentionRecorder; |
| |
| void RecordContention(uint64_t blocked_tid, uint64_t owner_tid, uint64_t nano_time_blocked); |
| void DumpContention(std::ostream& os) const; |
| |
| const LockLevel level_; // Support for lock hierarchy. |
| const char* const name_; |
| |
| // A log entry that records contention but makes no guarantee that either tid will be held live. |
| struct ContentionLogEntry { |
| ContentionLogEntry() : blocked_tid(0), owner_tid(0) {} |
| uint64_t blocked_tid; |
| uint64_t owner_tid; |
| AtomicInteger count; |
| }; |
| struct ContentionLogData { |
| ContentionLogEntry contention_log[kContentionLogSize]; |
| // The next entry in the contention log to be updated. Value ranges from 0 to |
| // kContentionLogSize - 1. |
| AtomicInteger cur_content_log_entry; |
| // Number of times the Mutex has been contended. |
| AtomicInteger contention_count; |
| // Sum of time waited by all contenders in ns. |
| volatile uint64_t wait_time; |
| void AddToWaitTime(uint64_t value); |
| ContentionLogData() : wait_time(0) {} |
| }; |
| ContentionLogData contetion_log_data_[kContentionLogDataSize]; |
| |
| public: |
| bool HasEverContended() const { |
| if (kLogLockContentions) { |
| return contetion_log_data_->contention_count > 0; |
| } |
| return false; |
| } |
| }; |
| |
| // A Mutex is used to achieve mutual exclusion between threads. A Mutex can be used to gain |
| // exclusive access to what it guards. A Mutex can be in one of two states: |
| // - Free - not owned by any thread, |
| // - Exclusive - owned by a single thread. |
| // |
| // The effect of locking and unlocking operations on the state is: |
| // State | ExclusiveLock | ExclusiveUnlock |
| // ------------------------------------------- |
| // Free | Exclusive | error |
| // Exclusive | Block* | Free |
| // * Mutex is not reentrant and so an attempt to ExclusiveLock on the same thread will result in |
| // an error. Being non-reentrant simplifies Waiting on ConditionVariables. |
| std::ostream& operator<<(std::ostream& os, const Mutex& mu); |
| class LOCKABLE Mutex : public BaseMutex { |
| public: |
| explicit Mutex(const char* name, LockLevel level = kDefaultMutexLevel, bool recursive = false); |
| ~Mutex(); |
| |
| virtual bool IsMutex() const { return true; } |
| |
| // Block until mutex is free then acquire exclusive access. |
| void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); |
| void Lock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } |
| |
| // Returns true if acquires exclusive access, false otherwise. |
| bool ExclusiveTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); |
| bool TryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true) { return ExclusiveTryLock(self); } |
| |
| // Release exclusive access. |
| void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); |
| void Unlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } |
| |
| // Is the current thread the exclusive holder of the Mutex. |
| bool IsExclusiveHeld(const Thread* self) const; |
| |
| // Assert that the Mutex is exclusively held by the current thread. |
| void AssertExclusiveHeld(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| CHECK(IsExclusiveHeld(self)) << *this; |
| } |
| } |
| void AssertHeld(const Thread* self) { AssertExclusiveHeld(self); } |
| |
| // Assert that the Mutex is not held by the current thread. |
| void AssertNotHeldExclusive(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| CHECK(!IsExclusiveHeld(self)) << *this; |
| } |
| } |
| void AssertNotHeld(const Thread* self) { AssertNotHeldExclusive(self); } |
| |
| // Id associated with exclusive owner. |
| uint64_t GetExclusiveOwnerTid() const; |
| |
| // Returns how many times this Mutex has been locked, it is better to use AssertHeld/NotHeld. |
| unsigned int GetDepth() const { |
| return recursion_count_; |
| } |
| |
| virtual void Dump(std::ostream& os) const; |
| |
| private: |
| #if ART_USE_FUTEXES |
| // 0 is unheld, 1 is held. |
| volatile int32_t state_; |
| // Exclusive owner. |
| volatile uint64_t exclusive_owner_; |
| // Number of waiting contenders. |
| volatile int32_t num_contenders_; |
| #else |
| pthread_mutex_t mutex_; |
| #endif |
| const bool recursive_; // Can the lock be recursively held? |
| unsigned int recursion_count_; |
| friend class ConditionVariable; |
| DISALLOW_COPY_AND_ASSIGN(Mutex); |
| }; |
| |
| // A ReaderWriterMutex is used to achieve mutual exclusion between threads, similar to a Mutex. |
| // Unlike a Mutex a ReaderWriterMutex can be used to gain exclusive (writer) or shared (reader) |
| // access to what it guards. A flaw in relation to a Mutex is that it cannot be used with a |
| // condition variable. A ReaderWriterMutex can be in one of three states: |
| // - Free - not owned by any thread, |
| // - Exclusive - owned by a single thread, |
| // - Shared(n) - shared amongst n threads. |
| // |
| // The effect of locking and unlocking operations on the state is: |
| // |
| // State | ExclusiveLock | ExclusiveUnlock | SharedLock | SharedUnlock |
| // ---------------------------------------------------------------------------- |
| // Free | Exclusive | error | SharedLock(1) | error |
| // Exclusive | Block | Free | Block | error |
| // Shared(n) | Block | error | SharedLock(n+1)* | Shared(n-1) or Free |
| // * for large values of n the SharedLock may block. |
| std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu); |
| class LOCKABLE ReaderWriterMutex : public BaseMutex { |
| public: |
| explicit ReaderWriterMutex(const char* name, LockLevel level = kDefaultMutexLevel); |
| ~ReaderWriterMutex(); |
| |
| virtual bool IsReaderWriterMutex() const { return true; } |
| |
| // Block until ReaderWriterMutex is free then acquire exclusive access. |
| void ExclusiveLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION(); |
| void WriterLock(Thread* self) EXCLUSIVE_LOCK_FUNCTION() { ExclusiveLock(self); } |
| |
| // Release exclusive access. |
| void ExclusiveUnlock(Thread* self) UNLOCK_FUNCTION(); |
| void WriterUnlock(Thread* self) UNLOCK_FUNCTION() { ExclusiveUnlock(self); } |
| |
| // Block until ReaderWriterMutex is free and acquire exclusive access. Returns true on success |
| // or false if timeout is reached. |
| #if HAVE_TIMED_RWLOCK |
| bool ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) |
| EXCLUSIVE_TRYLOCK_FUNCTION(true); |
| #endif |
| |
| // Block until ReaderWriterMutex is shared or free then acquire a share on the access. |
| void SharedLock(Thread* self) SHARED_LOCK_FUNCTION() ALWAYS_INLINE; |
| void ReaderLock(Thread* self) SHARED_LOCK_FUNCTION() { SharedLock(self); } |
| |
| // Try to acquire share of ReaderWriterMutex. |
| bool SharedTryLock(Thread* self) EXCLUSIVE_TRYLOCK_FUNCTION(true); |
| |
| // Release a share of the access. |
| void SharedUnlock(Thread* self) UNLOCK_FUNCTION() ALWAYS_INLINE; |
| void ReaderUnlock(Thread* self) UNLOCK_FUNCTION() { SharedUnlock(self); } |
| |
| // Is the current thread the exclusive holder of the ReaderWriterMutex. |
| bool IsExclusiveHeld(const Thread* self) const; |
| |
| // Assert the current thread has exclusive access to the ReaderWriterMutex. |
| void AssertExclusiveHeld(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| CHECK(IsExclusiveHeld(self)) << *this; |
| } |
| } |
| void AssertWriterHeld(const Thread* self) { AssertExclusiveHeld(self); } |
| |
| // Assert the current thread doesn't have exclusive access to the ReaderWriterMutex. |
| void AssertNotExclusiveHeld(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| CHECK(!IsExclusiveHeld(self)) << *this; |
| } |
| } |
| void AssertNotWriterHeld(const Thread* self) { AssertNotExclusiveHeld(self); } |
| |
| // Is the current thread a shared holder of the ReaderWriterMutex. |
| bool IsSharedHeld(const Thread* self) const; |
| |
| // Assert the current thread has shared access to the ReaderWriterMutex. |
| void AssertSharedHeld(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| // TODO: we can only assert this well when self != NULL. |
| CHECK(IsSharedHeld(self) || self == NULL) << *this; |
| } |
| } |
| void AssertReaderHeld(const Thread* self) { AssertSharedHeld(self); } |
| |
| // Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive |
| // mode. |
| void AssertNotHeld(const Thread* self) { |
| if (kDebugLocking && (gAborting == 0)) { |
| CHECK(!IsSharedHeld(self)) << *this; |
| } |
| } |
| |
| // Id associated with exclusive owner. |
| uint64_t GetExclusiveOwnerTid() const; |
| |
| virtual void Dump(std::ostream& os) const; |
| |
| private: |
| #if ART_USE_FUTEXES |
| // -1 implies held exclusive, +ve shared held by state_ many owners. |
| volatile int32_t state_; |
| // Exclusive owner. |
| volatile uint64_t exclusive_owner_; |
| // Pending readers. |
| volatile int32_t num_pending_readers_; |
| // Pending writers. |
| volatile int32_t num_pending_writers_; |
| #else |
| pthread_rwlock_t rwlock_; |
| #endif |
| DISALLOW_COPY_AND_ASSIGN(ReaderWriterMutex); |
| }; |
| |
| // ConditionVariables allow threads to queue and sleep. Threads may then be resumed individually |
| // (Signal) or all at once (Broadcast). |
| class ConditionVariable { |
| public: |
| explicit ConditionVariable(const char* name, Mutex& mutex); |
| ~ConditionVariable(); |
| |
| void Broadcast(Thread* self); |
| void Signal(Thread* self); |
| // TODO: No thread safety analysis on Wait and TimedWait as they call mutex operations via their |
| // pointer copy, thereby defeating annotalysis. |
| void Wait(Thread* self) NO_THREAD_SAFETY_ANALYSIS; |
| void TimedWait(Thread* self, int64_t ms, int32_t ns) NO_THREAD_SAFETY_ANALYSIS; |
| // Variant of Wait that should be used with caution. Doesn't validate that no mutexes are held |
| // when waiting. |
| // TODO: remove this. |
| void WaitHoldingLocks(Thread* self) NO_THREAD_SAFETY_ANALYSIS; |
| |
| private: |
| const char* const name_; |
| // The Mutex being used by waiters. It is an error to mix condition variables between different |
| // Mutexes. |
| Mutex& guard_; |
| #if ART_USE_FUTEXES |
| // A counter that is modified by signals and broadcasts. This ensures that when a waiter gives up |
| // their Mutex and another thread takes it and signals, the waiting thread observes that sequence_ |
| // changed and doesn't enter the wait. Modified while holding guard_, but is read by futex wait |
| // without guard_ held. |
| volatile int32_t sequence_; |
| // Number of threads that have come into to wait, not the length of the waiters on the futex as |
| // waiters may have been requeued onto guard_. Guarded by guard_. |
| volatile int32_t num_waiters_; |
| #else |
| pthread_cond_t cond_; |
| #endif |
| DISALLOW_COPY_AND_ASSIGN(ConditionVariable); |
| }; |
| |
| // Scoped locker/unlocker for a regular Mutex that acquires mu upon construction and releases it |
| // upon destruction. |
| class SCOPED_LOCKABLE MutexLock { |
| public: |
| explicit MutexLock(Thread* self, Mutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : self_(self), mu_(mu) { |
| mu_.ExclusiveLock(self_); |
| } |
| |
| ~MutexLock() UNLOCK_FUNCTION() { |
| mu_.ExclusiveUnlock(self_); |
| } |
| |
| private: |
| Thread* const self_; |
| Mutex& mu_; |
| DISALLOW_COPY_AND_ASSIGN(MutexLock); |
| }; |
| // Catch bug where variable name is omitted. "MutexLock (lock);" instead of "MutexLock mu(lock)". |
| #define MutexLock(x) COMPILE_ASSERT(0, mutex_lock_declaration_missing_variable_name) |
| |
| // Scoped locker/unlocker for a ReaderWriterMutex that acquires read access to mu upon |
| // construction and releases it upon destruction. |
| class SCOPED_LOCKABLE ReaderMutexLock { |
| public: |
| explicit ReaderMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : |
| self_(self), mu_(mu) { |
| mu_.SharedLock(self_); |
| } |
| |
| ~ReaderMutexLock() UNLOCK_FUNCTION() { |
| mu_.SharedUnlock(self_); |
| } |
| |
| private: |
| Thread* const self_; |
| ReaderWriterMutex& mu_; |
| DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); |
| }; |
| // Catch bug where variable name is omitted. "ReaderMutexLock (lock);" instead of |
| // "ReaderMutexLock mu(lock)". |
| #define ReaderMutexLock(x) COMPILE_ASSERT(0, reader_mutex_lock_declaration_missing_variable_name) |
| |
| // Scoped locker/unlocker for a ReaderWriterMutex that acquires write access to mu upon |
| // construction and releases it upon destruction. |
| class SCOPED_LOCKABLE WriterMutexLock { |
| public: |
| explicit WriterMutexLock(Thread* self, ReaderWriterMutex& mu) EXCLUSIVE_LOCK_FUNCTION(mu) : |
| self_(self), mu_(mu) { |
| mu_.ExclusiveLock(self_); |
| } |
| |
| ~WriterMutexLock() UNLOCK_FUNCTION() { |
| mu_.ExclusiveUnlock(self_); |
| } |
| |
| private: |
| Thread* const self_; |
| ReaderWriterMutex& mu_; |
| DISALLOW_COPY_AND_ASSIGN(WriterMutexLock); |
| }; |
| // Catch bug where variable name is omitted. "WriterMutexLock (lock);" instead of |
| // "WriterMutexLock mu(lock)". |
| #define WriterMutexLock(x) COMPILE_ASSERT(0, writer_mutex_lock_declaration_missing_variable_name) |
| |
| } // namespace art |
| |
| #endif // ART_RUNTIME_BASE_MUTEX_H_ |