| // Copyright 2017 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. |
| |
| #ifndef STARBOARD_COMMON_LOCKED_PTR_H_ |
| #define STARBOARD_COMMON_LOCKED_PTR_H_ |
| |
| #include "starboard/common/scoped_ptr.h" |
| #include "starboard/log.h" |
| #include "starboard/mutex.h" |
| |
| #ifdef __cplusplus |
| namespace starboard { |
| |
| // This class adds thread-safety to any class. Note when using LockedPtr<T>, |
| // the caller should use the returned object directly as a pointer without |
| // holding on it. This is enforced by making the ctors of Impl private. |
| template <typename Type> |
| class LockedPtr { |
| public: |
| template <typename ImplType> |
| class Impl { |
| public: |
| ~Impl() { |
| if (mutex_) { |
| mutex_->Release(); |
| } |
| } |
| |
| ImplType* operator->() { return ptr_; } |
| |
| private: |
| friend class LockedPtr<Type>; |
| |
| Impl(Mutex* mutex, ImplType* ptr) : mutex_(mutex), ptr_(ptr) { |
| SB_DCHECK(mutex); |
| SB_DCHECK(ptr); |
| |
| mutex_->Acquire(); |
| } |
| |
| // The copy ctor transfers the ownership. So only the last one holds the |
| // lock. This is safe as long as the user won't hold a reference to the |
| // returned object. |
| Impl(Impl& that) { |
| mutex_ = that.mutex_; |
| ptr_ = that.ptr_; |
| |
| that.mutex_ = NULL; |
| that.ptr_ = NULL; |
| } |
| |
| Mutex* mutex_; |
| ImplType* ptr_; |
| }; |
| |
| LockedPtr() : ptr_(NULL) {} |
| explicit LockedPtr(scoped_ptr<Type> ptr) : ptr_(ptr) { |
| SB_DCHECK(ptr != NULL); |
| } |
| |
| // This function is solely used to set the pointer to a valid value when it is |
| // not convenient to construct the object directly. So it checks if the |
| // existing |ptr_| is NULL. |
| void set(scoped_ptr<Type> ptr) { |
| starboard::ScopedLock scoped_lock(mutex_); |
| SB_DCHECK(ptr_ == NULL); |
| ptr_ = ptr.Pass(); |
| } |
| |
| bool is_valid() const { |
| starboard::ScopedLock scoped_lock(mutex_); |
| return ptr_ != NULL; |
| } |
| |
| Impl<Type> operator->() { |
| Impl<Type> impl(&mutex_, ptr_.get()); |
| return impl; |
| } |
| |
| Impl<const Type> operator->() const { |
| Impl<const Type> impl(&mutex_, ptr_.get()); |
| return impl; |
| } |
| |
| private: |
| mutable Mutex mutex_; |
| scoped_ptr<Type> ptr_; |
| }; |
| |
| } // namespace starboard |
| #endif // __cplusplus |
| |
| #endif // STARBOARD_COMMON_LOCKED_PTR_H_ |