Index: content/renderer/shared_memory_seqlock_reader.h |
diff --git a/content/renderer/shared_memory_seqlock_reader.h b/content/renderer/shared_memory_seqlock_reader.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..25234209c291071d5522b1217585ca0186eeff88 |
--- /dev/null |
+++ b/content/renderer/shared_memory_seqlock_reader.h |
@@ -0,0 +1,71 @@ |
+// Copyright (c) 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/shared_memory.h" |
+#include "content/common/shared_memory_seqlock_buffer.h" |
+ |
+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 |
+ |
+namespace content { |
+ |
+// 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_ |