| // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_ |
| #define BASE_SYNCHRONIZATION_LOCK_IMPL_H_ |
| |
| #include "base/base_export.h" |
| #include "base/logging.h" |
| #include "base/macros.h" |
| #include "base/thread_annotations.h" |
| #include "build/build_config.h" |
| |
| #if defined(OS_WIN) |
| #include "base/win/windows_types.h" |
| #elif defined(OS_POSIX) || defined(OS_FUCHSIA) |
| #include <errno.h> |
| #include <pthread.h> |
| #endif |
| |
| namespace base { |
| namespace internal { |
| |
| // This class implements the underlying platform-specific spin-lock mechanism |
| // used for the Lock class. Most users should not use LockImpl directly, but |
| // should instead use Lock. |
| class BASE_EXPORT LockImpl { |
| public: |
| #if defined(OS_WIN) |
| using NativeHandle = CHROME_SRWLOCK; |
| #elif defined(OS_POSIX) || defined(OS_FUCHSIA) |
| using NativeHandle = pthread_mutex_t; |
| #endif |
| |
| LockImpl(); |
| ~LockImpl(); |
| |
| // If the lock is not held, take it and return true. If the lock is already |
| // held by something else, immediately return false. |
| bool Try(); |
| |
| // Take the lock, blocking until it is available if necessary. |
| void Lock(); |
| |
| // Release the lock. This must only be called by the lock's holder: after |
| // a successful call to Try, or a call to Lock. |
| inline void Unlock(); |
| |
| // Return the native underlying lock. |
| // TODO(awalker): refactor lock and condition variables so that this is |
| // unnecessary. |
| NativeHandle* native_handle() { return &native_handle_; } |
| |
| #if defined(OS_POSIX) || defined(OS_FUCHSIA) |
| // Whether this lock will attempt to use priority inheritance. |
| static bool PriorityInheritanceAvailable(); |
| #endif |
| |
| private: |
| NativeHandle native_handle_; |
| |
| DISALLOW_COPY_AND_ASSIGN(LockImpl); |
| }; |
| |
| #if defined(OS_WIN) |
| void LockImpl::Unlock() { |
| ::ReleaseSRWLockExclusive(reinterpret_cast<PSRWLOCK>(&native_handle_)); |
| } |
| #elif defined(OS_POSIX) || defined(OS_FUCHSIA) |
| void LockImpl::Unlock() { |
| int rv = pthread_mutex_unlock(&native_handle_); |
| DCHECK_EQ(rv, 0) << ". " << strerror(rv); |
| } |
| #endif |
| |
| // This is an implementation used for AutoLock templated on the lock type. |
| template <class LockType> |
| class SCOPED_LOCKABLE BasicAutoLock { |
| public: |
| struct AlreadyAcquired {}; |
| |
| explicit BasicAutoLock(LockType& lock) EXCLUSIVE_LOCK_FUNCTION(lock) |
| : lock_(lock) { |
| lock_.Acquire(); |
| } |
| |
| BasicAutoLock(LockType& lock, const AlreadyAcquired&) |
| EXCLUSIVE_LOCKS_REQUIRED(lock) |
| : lock_(lock) { |
| lock_.AssertAcquired(); |
| } |
| |
| ~BasicAutoLock() UNLOCK_FUNCTION() { |
| lock_.AssertAcquired(); |
| lock_.Release(); |
| } |
| |
| private: |
| LockType& lock_; |
| DISALLOW_COPY_AND_ASSIGN(BasicAutoLock); |
| }; |
| |
| // This is an implementation used for AutoUnlock templated on the lock type. |
| template <class LockType> |
| class BasicAutoUnlock { |
| public: |
| explicit BasicAutoUnlock(LockType& lock) : lock_(lock) { |
| // We require our caller to have the lock. |
| lock_.AssertAcquired(); |
| lock_.Release(); |
| } |
| |
| ~BasicAutoUnlock() { lock_.Acquire(); } |
| |
| private: |
| LockType& lock_; |
| DISALLOW_COPY_AND_ASSIGN(BasicAutoUnlock); |
| }; |
| |
| // This is an implementation used for AutoLockMaybe templated on the lock type. |
| template <class LockType> |
| class SCOPED_LOCKABLE BasicAutoLockMaybe { |
| public: |
| explicit BasicAutoLockMaybe(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock) |
| : lock_(lock) { |
| if (lock_) |
| lock_->Acquire(); |
| } |
| |
| ~BasicAutoLockMaybe() UNLOCK_FUNCTION() { |
| if (lock_) { |
| lock_->AssertAcquired(); |
| lock_->Release(); |
| } |
| } |
| |
| private: |
| LockType* const lock_; |
| DISALLOW_COPY_AND_ASSIGN(BasicAutoLockMaybe); |
| }; |
| |
| // This is an implementation used for ReleasableAutoLock templated on the lock |
| // type. |
| template <class LockType> |
| class SCOPED_LOCKABLE BasicReleasableAutoLock { |
| public: |
| explicit BasicReleasableAutoLock(LockType* lock) EXCLUSIVE_LOCK_FUNCTION(lock) |
| : lock_(lock) { |
| DCHECK(lock_); |
| lock_->Acquire(); |
| } |
| |
| ~BasicReleasableAutoLock() UNLOCK_FUNCTION() { |
| if (lock_) { |
| lock_->AssertAcquired(); |
| lock_->Release(); |
| } |
| } |
| |
| void Release() UNLOCK_FUNCTION() { |
| DCHECK(lock_); |
| lock_->AssertAcquired(); |
| lock_->Release(); |
| lock_ = nullptr; |
| } |
| |
| private: |
| LockType* lock_; |
| DISALLOW_COPY_AND_ASSIGN(BasicReleasableAutoLock); |
| }; |
| |
| } // namespace internal |
| } // namespace base |
| |
| #endif // BASE_SYNCHRONIZATION_LOCK_IMPL_H_ |