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// Copyright 2013 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 CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_
#define CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/shared_memory.h"
#include "content/common/shared_memory_seqlock_buffer.h"
namespace content {
namespace internal {
class SharedMemorySeqLockReaderBase {
protected:
SharedMemorySeqLockReaderBase();
virtual ~SharedMemorySeqLockReaderBase();
void* InitializeSharedMemory(
base::SharedMemoryHandle shared_memory_handle,
size_t buffer_size);
bool FetchFromBuffer(content::OneWriterSeqLock* seqlock, void* final,
void* temp, void* from, size_t size);
static const int kMaximumContentionCount = 10;
base::SharedMemoryHandle renderer_shared_memory_handle_;
scoped_ptr<base::SharedMemory> renderer_shared_memory_;
};
} // namespace internal
// Template argument Data should be a pod-like structure only containing
// data fields, such that it is copyable by memcpy method.
template<typename Data>
class SharedMemorySeqLockReader
: private internal::SharedMemorySeqLockReaderBase {
public:
SharedMemorySeqLockReader() : buffer_(0) { }
virtual ~SharedMemorySeqLockReader() { }
bool GetLatestData(Data* data) {
DCHECK(buffer_);
DCHECK(sizeof(*data) == sizeof(*temp_buffer_));
return FetchFromBuffer(&buffer_->seqlock, data, temp_buffer_.get(),
&buffer_->data, sizeof(*temp_buffer_));
}
bool Initialize(base::SharedMemoryHandle shared_memory_handle) {
if (void* memory = InitializeSharedMemory(
shared_memory_handle, sizeof(SharedMemorySeqLockBuffer<Data>))) {
buffer_ = static_cast<SharedMemorySeqLockBuffer<Data>*>(memory);
temp_buffer_.reset(new Data);
return true;
}
return false;
}
private:
SharedMemorySeqLockBuffer<Data>* buffer_;
scoped_ptr<Data> temp_buffer_;
DISALLOW_COPY_AND_ASSIGN(SharedMemorySeqLockReader);
};
} // namespace content
#endif // CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_
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