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| 1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_ | |
| 6 #define CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_ | |
| 7 | |
| 8 #include <stddef.h> | |
| 9 | |
| 10 #include <memory> | |
| 11 | |
| 12 #include "base/logging.h" | |
| 13 #include "base/macros.h" | |
| 14 #include "base/memory/shared_memory.h" | |
| 15 #include "device/base/synchronization/shared_memory_seqlock_buffer.h" | |
| 16 | |
| 17 namespace content { | |
| 18 namespace internal { | |
| 19 | |
| 20 class SharedMemorySeqLockReaderBase { | |
| 21 protected: | |
| 22 SharedMemorySeqLockReaderBase(); | |
| 23 virtual ~SharedMemorySeqLockReaderBase(); | |
| 24 | |
| 25 void* InitializeSharedMemory( | |
| 26 base::SharedMemoryHandle shared_memory_handle, | |
| 27 size_t buffer_size); | |
| 28 | |
| 29 bool FetchFromBuffer(device::OneWriterSeqLock* seqlock, | |
| 30 void* final, | |
| 31 void* temp, | |
| 32 void* from, | |
| 33 size_t size); | |
| 34 | |
| 35 static const int kMaximumContentionCount = 10; | |
| 36 base::SharedMemoryHandle renderer_shared_memory_handle_; | |
| 37 std::unique_ptr<base::SharedMemory> renderer_shared_memory_; | |
| 38 }; | |
| 39 | |
| 40 } // namespace internal | |
| 41 | |
| 42 // Template argument Data should be a pod-like structure only containing | |
| 43 // data fields, such that it is copyable by memcpy method. | |
| 44 template<typename Data> | |
| 45 class SharedMemorySeqLockReader | |
| 46 : private internal::SharedMemorySeqLockReaderBase { | |
| 47 public: | |
| 48 SharedMemorySeqLockReader() : buffer_(0) { } | |
| 49 virtual ~SharedMemorySeqLockReader() { } | |
| 50 | |
| 51 bool GetLatestData(Data* data) { | |
| 52 DCHECK(buffer_); | |
| 53 DCHECK(sizeof(*data) == sizeof(*temp_buffer_)); | |
| 54 return FetchFromBuffer(&buffer_->seqlock, data, temp_buffer_.get(), | |
| 55 &buffer_->data, sizeof(*temp_buffer_)); | |
| 56 } | |
| 57 | |
| 58 bool Initialize(base::SharedMemoryHandle shared_memory_handle) { | |
| 59 if (void* memory = InitializeSharedMemory( | |
| 60 shared_memory_handle, | |
| 61 sizeof(device::SharedMemorySeqLockBuffer<Data>))) { | |
| 62 buffer_ = static_cast<device::SharedMemorySeqLockBuffer<Data>*>(memory); | |
| 63 temp_buffer_.reset(new Data); | |
| 64 return true; | |
| 65 } | |
| 66 return false; | |
| 67 } | |
| 68 | |
| 69 private: | |
| 70 device::SharedMemorySeqLockBuffer<Data>* buffer_; | |
| 71 std::unique_ptr<Data> temp_buffer_; | |
| 72 | |
| 73 DISALLOW_COPY_AND_ASSIGN(SharedMemorySeqLockReader); | |
| 74 }; | |
| 75 | |
| 76 } // namespace content | |
| 77 | |
| 78 #endif // CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_ | |
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