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 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 // Flush the memory-mapped section to disk (synchronously). 42 void Flush(); 43 44 private: 45 virtual ~MappedFile(); 46 47 bool init_; 48 #if defined(OS_WIN) 49 HANDLE section_; 50 #endif 51 void* buffer_; // Address of the memory mapped buffer. 52 size_t view_size_; // Size of the memory pointed by buffer_. 53 #if defined(POSIX_AVOID_MMAP) 54 void* snapshot_; // Copy of the buffer taken when it was last flushed. 55 #endif 56 57 DISALLOW_COPY_AND_ASSIGN(MappedFile); 58 }; 59 60 // Helper class for calling Flush() on exit from the current scope. 61 class ScopedFlush { 62 public: 63 explicit ScopedFlush(MappedFile* file) : file_(file) {} 64 ~ScopedFlush() { 65 file_->Flush(); 66 } 67 private: 68 MappedFile* file_; 69 }; 70 71 } // namespace disk_cache 72 73 #endif // NET_DISK_CACHE_MAPPED_FILE_H_ 74