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_BLOCKFILE_MAPPED_FILE_H_ 8 #define NET_DISK_CACHE_BLOCKFILE_MAPPED_FILE_H_ 9 10 #include "net/base/net_export.h" 11 #include "net/disk_cache/blockfile/file.h" 12 #include "net/disk_cache/blockfile/file_block.h" 13 14 namespace base { 15 class FilePath; 16 } 17 18 namespace 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). 24 class 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 // Heats up the file system cache and make sure the file is fully 50 // readable (synchronously). 51 bool Preload(); 52 53 private: 54 virtual ~MappedFile(); 55 56 bool init_; 57 #if defined(OS_WIN) 58 HANDLE section_; 59 #endif 60 void* buffer_; // Address of the memory mapped buffer. 61 size_t view_size_; // Size of the memory pointed by buffer_. 62 #if defined(POSIX_AVOID_MMAP) 63 void* snapshot_; // Copy of the buffer taken when it was last flushed. 64 #endif 65 66 DISALLOW_COPY_AND_ASSIGN(MappedFile); 67 }; 68 69 // Helper class for calling Flush() on exit from the current scope. 70 class ScopedFlush { 71 public: 72 explicit ScopedFlush(MappedFile* file) : file_(file) {} 73 ~ScopedFlush() { 74 file_->Flush(); 75 } 76 private: 77 MappedFile* file_; 78 }; 79 80 } // namespace disk_cache 81 82 #endif // NET_DISK_CACHE_BLOCKFILE_MAPPED_FILE_H_ 83