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// Copyright (c) 2013 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.
#ifndef STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
#define STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
#include <queue>
#include <stack>
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/memory/weak_ptr.h"
#include "storage/browser/fileapi/file_system_operation.h"
#include "storage/browser/fileapi/file_system_url.h"
namespace storage {
class FileSystemContext;
class FileSystemOperationRunner;
// A base class for recursive operation delegates.
//
// In short, each subclass should override ProcessFile and ProcessDirectory
// to process a directory or a file. To start the recursive operation it
// should also call StartRecursiveOperation.
class STORAGE_EXPORT RecursiveOperationDelegate
: public base::SupportsWeakPtr<RecursiveOperationDelegate> {
public:
typedef FileSystemOperation::StatusCallback StatusCallback;
typedef FileSystemOperation::FileEntryList FileEntryList;
virtual ~RecursiveOperationDelegate();
// This is called when the consumer of this instance starts a non-recursive
// operation.
virtual void Run() = 0;
// This is called when the consumer of this instance starts a recursive
// operation.
virtual void RunRecursively() = 0;
// This is called each time a file is found while recursively
// performing an operation.
virtual void ProcessFile(const FileSystemURL& url,
const StatusCallback& callback) = 0;
// This is called each time a directory is found while recursively
// performing an operation.
virtual void ProcessDirectory(const FileSystemURL& url,
const StatusCallback& callback) = 0;
// This is called each time after files and subdirectories for a
// directory is processed while recursively performing an operation.
virtual void PostProcessDirectory(const FileSystemURL& url,
const StatusCallback& callback) = 0;
// Cancels the currently running operation.
void Cancel();
protected:
explicit RecursiveOperationDelegate(FileSystemContext* file_system_context);
// Starts to process files/directories recursively from the given |root|.
// This will call ProcessFile and ProcessDirectory on each file or directory.
//
// First, this tries to call ProcessFile with |root| regardless whether it is
// actually a file or a directory. If it is a directory, ProcessFile should
// return File::FILE_NOT_A_FILE.
//
// For each directory, the recursive operation works as follows:
// ProcessDirectory is called first for the directory.
// Then the directory contents are read (to obtain its sub directories and
// files in it).
// ProcessFile is called for found files. This may run in parallel.
// The same step is recursively applied to each subdirectory.
// After all files and subdirectories in a directory are processed,
// PostProcessDirectory is called for the directory.
// Here is an example;
// a_dir/ -+- b1_dir/ -+- c1_dir/ -+- d1_file
// | | |
// | +- c2_file +- d2_file
// |
// +- b2_dir/ --- e_dir/
// |
// +- b3_file
// |
// +- b4_file
// Then traverse order is:
// ProcessFile(a_dir) (This should return File::FILE_NOT_A_FILE).
// ProcessDirectory(a_dir).
// ProcessFile(b3_file), ProcessFile(b4_file). (in parallel).
// ProcessDirectory(b1_dir).
// ProcessFile(c2_file)
// ProcessDirectory(c1_dir).
// ProcessFile(d1_file), ProcessFile(d2_file). (in parallel).
// PostProcessDirectory(c1_dir)
// PostProcessDirectory(b1_dir).
// ProcessDirectory(b2_dir)
// ProcessDirectory(e_dir)
// PostProcessDirectory(e_dir)
// PostProcessDirectory(b2_dir)
// PostProcessDirectory(a_dir)
//
// |callback| is fired with base::File::FILE_OK when every file/directory
// under |root| is processed, or fired earlier when any suboperation fails.
void StartRecursiveOperation(const FileSystemURL& root,
const StatusCallback& callback);
FileSystemContext* file_system_context() { return file_system_context_; }
const FileSystemContext* file_system_context() const {
return file_system_context_;
}
FileSystemOperationRunner* operation_runner();
// Called when Cancel() is called. This is a hook to do something more
// in a derived class. By default, do nothing.
virtual void OnCancel();
private:
void DidTryProcessFile(const FileSystemURL& root,
base::File::Error error);
void ProcessNextDirectory();
void DidProcessDirectory(base::File::Error error);
void DidReadDirectory(const FileSystemURL& parent,
base::File::Error error,
const FileEntryList& entries,
bool has_more);
void ProcessPendingFiles();
void DidProcessFile(base::File::Error error);
void ProcessSubDirectory();
void DidPostProcessDirectory(base::File::Error error);
// Called when all recursive operation is done (or an error occurs).
void Done(base::File::Error error);
FileSystemContext* file_system_context_;
StatusCallback callback_;
std::stack<FileSystemURL> pending_directories_;
std::stack<std::queue<FileSystemURL> > pending_directory_stack_;
std::queue<FileSystemURL> pending_files_;
int inflight_operations_;
bool canceled_;
DISALLOW_COPY_AND_ASSIGN(RecursiveOperationDelegate);
};
} // namespace storage
#endif // STORAGE_BROWSER_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_