blob: f39955c47f50c8e0d71f7af2daff75cfee7efd1e [file] [log] [blame]
// Copyright (c) 2012 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.
// See net/disk_cache/disk_cache.h for the public interface of the cache.
#include <stddef.h>
#include "base/macros.h"
#include "net/base/net_export.h"
#include "net/disk_cache/blockfile/file.h"
#include "net/disk_cache/blockfile/file_block.h"
namespace base {
class FilePath;
namespace disk_cache {
// This class implements a memory mapped file used to access block-files. The
// idea is that the header and bitmap will be memory mapped all the time, and
// the actual data for the blocks will be access asynchronously (most of the
// time).
class NET_EXPORT_PRIVATE MappedFile : public File {
MappedFile() : File(true), init_(false) {}
// Performs object initialization. name is the file to use, and size is the
// amount of data to memory map from the file. If size is 0, the whole file
// will be mapped in memory.
void* Init(const base::FilePath& name, size_t size);
void* buffer() const {
return buffer_;
// Loads or stores a given block from the backing file (synchronously).
bool Load(const FileBlock* block);
bool Store(const FileBlock* block);
// Flush the memory-mapped section to disk (synchronously).
void Flush();
// Heats up the file system cache and make sure the file is fully
// readable (synchronously).
bool Preload();
~MappedFile() override;
bool init_;
#if defined(OS_WIN)
HANDLE section_;
void* buffer_; // Address of the memory mapped buffer.
size_t view_size_; // Size of the memory pointed by buffer_.
#if defined(POSIX_AVOID_MMAP)
void* snapshot_; // Copy of the buffer taken when it was last flushed.
// Helper class for calling Flush() on exit from the current scope.
class ScopedFlush {
explicit ScopedFlush(MappedFile* file) : file_(file) {}
~ScopedFlush() {
MappedFile* file_;
} // namespace disk_cache