| // Copyright 2015 Google Inc. All Rights Reserved. |
| // |
| // 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. |
| |
| // Module Overview: Starboard Mutex module |
| // |
| // Defines a mutually exclusive lock that can be used to coordinate with other |
| // threads. |
| |
| #ifndef STARBOARD_MUTEX_H_ |
| #define STARBOARD_MUTEX_H_ |
| |
| #include "starboard/export.h" |
| #include "starboard/thread_types.h" |
| #include "starboard/types.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| // Enumeration of possible results from acquiring a mutex. |
| typedef enum SbMutexResult { |
| // The mutex was acquired successfully. |
| kSbMutexAcquired, |
| |
| // The mutex was not acquired because it was held by someone else. |
| kSbMutexBusy, |
| |
| // The mutex has already been destroyed. |
| kSbMutexDestroyed, |
| } SbMutexResult; |
| |
| // Indicates whether the given result is a success. A value of |true| indicates |
| // that the mutex was acquired. |
| // |
| // |result|: The result being checked. |
| static SB_C_FORCE_INLINE bool SbMutexIsSuccess(SbMutexResult result) { |
| return result == kSbMutexAcquired; |
| } |
| |
| // Creates a new mutex. The return value indicates whether the function |
| // was able to create a new mutex. |
| // |
| // |out_mutex|: The handle to the newly created mutex. |
| SB_EXPORT bool SbMutexCreate(SbMutex* out_mutex); |
| |
| // Destroys a mutex. The return value indicates whether the destruction was |
| // successful. |
| // |
| // |mutex|: The mutex to be invalidated. |
| SB_EXPORT bool SbMutexDestroy(SbMutex* mutex); |
| |
| // Acquires |mutex|, blocking indefinitely. The return value identifies |
| // the acquisition result. SbMutexes are not reentrant, so a recursive |
| // acquisition blocks forever. |
| // |
| // |mutex|: The mutex to be acquired. |
| SB_EXPORT SbMutexResult SbMutexAcquire(SbMutex* mutex); |
| |
| // Acquires |mutex|, without blocking. The return value identifies |
| // the acquisition result. SbMutexes are not reentrant, so a recursive |
| // acquisition always fails. |
| // |
| // |mutex|: The mutex to be acquired. |
| SB_EXPORT SbMutexResult SbMutexAcquireTry(SbMutex* mutex); |
| |
| // Releases |mutex| held by the current thread. The return value indicates |
| // whether the release was successful. Releases should always be successful |
| // if |mutex| is held by the current thread. |
| // |
| // |mutex|: The mutex to be released. |
| SB_EXPORT bool SbMutexRelease(SbMutex* mutex); |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |
| |
| #ifdef __cplusplus |
| namespace starboard { |
| |
| // Inline class wrapper for SbMutex. |
| class Mutex { |
| public: |
| Mutex() : mutex_() { SbMutexCreate(&mutex_); } |
| |
| ~Mutex() { SbMutexDestroy(&mutex_); } |
| |
| void Acquire() const { SbMutexAcquire(&mutex_); } |
| bool AcquireTry() const { |
| return SbMutexAcquireTry(&mutex_) == kSbMutexAcquired; |
| } |
| |
| void Release() const { SbMutexRelease(&mutex_); } |
| |
| private: |
| friend class ConditionVariable; |
| SbMutex* mutex() const { return &mutex_; } |
| |
| mutable SbMutex mutex_; |
| }; |
| |
| // Scoped lock holder that works on starboard::Mutex. |
| class ScopedLock { |
| public: |
| explicit ScopedLock(const Mutex& mutex) : mutex_(mutex) { mutex_.Acquire(); } |
| |
| ~ScopedLock() { mutex_.Release(); } |
| |
| private: |
| const Mutex& mutex_; |
| }; |
| |
| // Scoped lock holder that works on starboard::Mutex which uses AcquireTry() |
| // instead of Acquire(). |
| class ScopedTryLock { |
| public: |
| explicit ScopedTryLock(const Mutex& mutex) : mutex_(mutex) { |
| is_locked_ = mutex_.AcquireTry(); |
| } |
| |
| ~ScopedTryLock() { |
| if (is_locked_) { |
| mutex_.Release(); |
| } |
| } |
| |
| bool is_locked() const { return is_locked_; } |
| |
| private: |
| const Mutex& mutex_; |
| bool is_locked_; |
| }; |
| |
| } // namespace starboard |
| #endif |
| |
| #endif // STARBOARD_MUTEX_H_ |