(For-try) Divide recursive Copy/Move into multiple async tasks

webkit/fileapi/recursive_operation_delegate.h

+// 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 WEBKIT_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
+#define WEBKIT_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_
+
+#include <queue>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "webkit/fileapi/file_system_operation.h"
+#include "webkit/fileapi/file_system_url.h"
+
+namespace fileapi {
+
+class FileSystemContext;
+class LocalFileSystemOperation;
+
+// A base class for recursive operation delegates.
+// This also provides some convenient default implementations for subclasses
+// like StartRecursiveOperation() and  NewOperation().
+//
+// 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.
+//
+// Each subclass can call NewOperation to create a new file system operation
+// to perform a sub-operations, e.g. can call RemoveFile for recursive Remove.
+class RecursiveOperationDelegate
+    : public base::SupportsWeakPtr<RecursiveOperationDelegate> {
+ public:
+  typedef FileSystemOperation::StatusCallback StatusCallback;
+  typedef FileSystemOperation::FileEntryList FileEntryList;
+
+  RecursiveOperationDelegate(LocalFileSystemOperation* original_operation);
+  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;
+
+ protected:
+  // Starts to process files/directories recursively from the given |root|.
+  // This will call ProcessFile and ProcessDirectory on each directory or file.
+  // If the given |root| is a file this simply calls ProcessFile and exits.
+  //
+  // |callback| is fired with base::PLATFORM_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);
+
+  // Returns new sub-operation for a given |url|.
+  // This may return NULL if any error has happened.
+  // If non-null |error| is given it is set to the error code.
+  LocalFileSystemOperation* NewOperation(const FileSystemURL& url,
+                                         base::PlatformFileError* error);
+
+  FileSystemContext* file_system_context();
+
+ private:
+  void ProcessNextDirectory(base::PlatformFileError error);
+  void DidProcessFile(base::PlatformFileError error);
+  void DidProcessDirectory(const FileSystemURL& url,
+                           base::PlatformFileError error);
+  void DidReadDirectory(
+      const FileSystemURL& parent,
+      base::PlatformFileError error,
+      const FileEntryList& entries,
+      bool has_more);
+  void DidTryProcessFile(base::PlatformFileError previous_error,
+                         base::PlatformFileError error);
+
+  LocalFileSystemOperation* original_operation_;
+  StatusCallback callback_;
+  std::queue<FileSystemURL> pending_directories_;
+  int inflight_operations_;
+
+  DISALLOW_COPY_AND_ASSIGN(RecursiveOperationDelegate);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_RECURSIVE_OPERATION_DELEGATE_H_