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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 "base/logging.h" | |
9 #include "base/memory/scoped_ptr.h" | |
10 #include "base/memory/shared_memory.h" | |
11 #include "content/common/shared_memory_seqlock_buffer.h" | |
12 | |
13 namespace content { | |
14 namespace internal { | |
15 | |
16 class SharedMemorySeqLockReaderBase { | |
17 protected: | |
18 SharedMemorySeqLockReaderBase(); | |
19 virtual ~SharedMemorySeqLockReaderBase(); | |
20 | |
21 void* InitializeSharedMemory( | |
22 base::SharedMemoryHandle shared_memory_handle, | |
23 size_t buffer_size); | |
24 | |
25 bool FetchFromBuffer(content::OneWriterSeqLock* seqlock, void* final, | |
26 void* temp, void* from, size_t size); | |
27 | |
28 static const int kMaximumContentionCount = 10; | |
29 base::SharedMemoryHandle renderer_shared_memory_handle_; | |
30 scoped_ptr<base::SharedMemory> renderer_shared_memory_; | |
31 }; | |
32 | |
33 } // namespace internal | |
34 | |
35 // Template argument Data should be a pod-like structure only containing | |
36 // data fields, such that it is copyable by memcpy method. | |
37 template<typename Data> | |
38 class SharedMemorySeqLockReader | |
39 : private internal::SharedMemorySeqLockReaderBase { | |
40 public: | |
41 SharedMemorySeqLockReader() : buffer_(0) { } | |
42 virtual ~SharedMemorySeqLockReader() { } | |
43 | |
44 bool GetLatestData(Data* data) { | |
45 DCHECK(buffer_); | |
46 DCHECK(sizeof(*data) == sizeof(*temp_buffer_)); | |
47 return FetchFromBuffer(&buffer_->seqlock, data, temp_buffer_.get(), | |
48 &buffer_->data, sizeof(*temp_buffer_)); | |
49 } | |
50 | |
51 bool Initialize(base::SharedMemoryHandle shared_memory_handle) { | |
52 if (void* memory = InitializeSharedMemory( | |
53 shared_memory_handle, sizeof(SharedMemorySeqLockBuffer<Data>))) { | |
54 buffer_ = static_cast<SharedMemorySeqLockBuffer<Data>*>(memory); | |
55 temp_buffer_.reset(new Data); | |
56 return true; | |
57 } | |
58 return false; | |
59 } | |
60 | |
61 private: | |
62 SharedMemorySeqLockBuffer<Data>* buffer_; | |
63 scoped_ptr<Data> temp_buffer_; | |
64 | |
65 DISALLOW_COPY_AND_ASSIGN(SharedMemorySeqLockReader); | |
66 }; | |
67 | |
68 } // namespace content | |
69 | |
70 #endif // CONTENT_RENDERER_SHARED_MEMORY_SEQLOCK_READER_H_ | |
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