1// Copyright (c) 2012 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// See net/disk_cache/disk_cache.h for the public interface of the cache. 6 7#ifndef NET_DISK_CACHE_MAPPED_FILE_H_ 8#define NET_DISK_CACHE_MAPPED_FILE_H_ 9 10#include "net/base/net_export.h" 11#include "net/disk_cache/file.h" 12#include "net/disk_cache/file_block.h" 13 14namespace base { 15class FilePath; 16} 17 18namespace disk_cache { 19 20// This class implements a memory mapped file used to access block-files. The 21// idea is that the header and bitmap will be memory mapped all the time, and 22// the actual data for the blocks will be access asynchronously (most of the 23// time). 24class NET_EXPORT_PRIVATE MappedFile : public File { 25 public: 26 MappedFile() : File(true), init_(false) {} 27 28 // Performs object initialization. name is the file to use, and size is the 29 // amount of data to memory map from the file. If size is 0, the whole file 30 // will be mapped in memory. 31 void* Init(const base::FilePath& name, size_t size); 32 33 void* buffer() const { 34 return buffer_; 35 } 36 37 // Loads or stores a given block from the backing file (synchronously). 38 bool Load(const FileBlock* block); 39 bool Store(const FileBlock* block); 40 41 // Asynchronous versions of Load/Store, following the semantics of File::Read 42 // and File::Write. 43 bool Load(const FileBlock* block, FileIOCallback* callback, bool* completed); 44 bool Store(const FileBlock* block, FileIOCallback* callback, bool* completed); 45 46 // Flush the memory-mapped section to disk (synchronously). 47 void Flush(); 48 49 private: 50 virtual ~MappedFile(); 51 52 bool init_; 53#if defined(OS_WIN) 54 HANDLE section_; 55#endif 56 void* buffer_; // Address of the memory mapped buffer. 57 size_t view_size_; // Size of the memory pointed by buffer_. 58#if defined(POSIX_AVOID_MMAP) 59 void* snapshot_; // Copy of the buffer taken when it was last flushed. 60#endif 61 62 DISALLOW_COPY_AND_ASSIGN(MappedFile); 63}; 64 65// Helper class for calling Flush() on exit from the current scope. 66class ScopedFlush { 67 public: 68 explicit ScopedFlush(MappedFile* file) : file_(file) {} 69 ~ScopedFlush() { 70 file_->Flush(); 71 } 72 private: 73 MappedFile* file_; 74}; 75 76} // namespace disk_cache 77 78#endif // NET_DISK_CACHE_MAPPED_FILE_H_ 79