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// Copyright (c) 2006-2009 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.
//
// FileSystemAccessor provides functions so consumers can do file access
// asynchronously. It would PostTask to FILE thread to access file info, then on
// completion PostTask back to the caller thread and pass the result back.
// Here is an example on how to use it to get file size:
// 1. Define a callback function so FileSystemAccessor could run it after the
// task has been completed:
// void Foo::GetFileSizeCallback(int64 result, void* param) {
// }
// 2. Call static function FileSystemAccessor::RequestFileSize, provide file
// path, param (any object you want to pass back to the callback function)
// and callback:
// FileSystemAccessor::RequestFileSize(
// path,
// param,
// NewCallback(this, &Foo::GetFileSizeCallback));
// 3. FileSystemAceessor would PostTask to FILE thread to get file size, then
// on completion it would PostTask back to the current thread and run
// Foo::GetFileSizeCallback.
//
#ifndef CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
#define CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
#include "base/scoped_ptr.h"
#include "base/ref_counted.h"
#include "base/task.h"
class FilePath;
class MessageLoop;
class FileSystemAccessor
: public base::RefCountedThreadSafe<FileSystemAccessor> {
public:
typedef Callback2<int64, void*>::Type FileSizeCallback;
virtual ~FileSystemAccessor();
// Request to get file size.
//
// param is an object that is owned by the caller and needs to pass back to
// the caller by FileSystemAccessor through the callback function.
// It can be set to NULL if no object needs to pass back.
//
// FileSizeCallback function is defined as:
// void f(int64 result, void* param);
// Variable result has the file size. If the file does not exist or there is
// error accessing the file, result is set to -1. If the given path is a
// directory, result is set to 0.
static void RequestFileSize(const FilePath& path,
void* param,
FileSizeCallback* callback);
private:
FileSystemAccessor(void* param, FileSizeCallback* callback);
// Get file size on the worker thread and pass result back to the caller
// thread.
void GetFileSize(const FilePath& path);
// Getting file size completed, callback to reply message.
void GetFileSizeCompleted(int64 result);
MessageLoop* caller_loop_;
void* param_;
scoped_ptr<FileSizeCallback> callback_;
DISALLOW_COPY_AND_ASSIGN(FileSystemAccessor);
};
#endif // CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
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