Refactor FileSystemOperation to take callback for each method.

webkit/fileapi/file_system_operation_interface.h

 // 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.
 
 #ifndef WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_INTERFACE_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_INTERFACE_H_
 
+#include "base/file_util_proxy.h"
+#include "base/platform_file.h"
 #include "base/process.h"
 
 namespace base {
 class Time;
 }  // namespace base
 
 namespace net {
 class URLRequest;
 class URLRequestContext;
 }  // namespace net
 
 class GURL;
 
 namespace fileapi {
 
-class FileSystemCallbackDispatcher;
 class FileSystemOperation;
 
 // The interface class for FileSystemOperation implementations.
 //
 // This interface defines file system operations required to implement
 // "File API: Directories and System"
 // http://www.w3.org/TR/file-system-api/
 //
 // DESIGN NOTES
 //
 // This class is designed to
 //
 // 1) Serve one-time file system operation per instance.  Only one
 // method(CreateFile, CreateDirectory, Copy, Move, DirectoryExists,
 // GetMetadata, ReadDirectory and Remove) may be called during the
 // lifetime of this object and it should be called no more than once.
 //
 // 2) Be self-destructed, or get deleted via base::Owned() after the
 // operation finishes and completion callback is called.
 //
-// 3) Deliver the results of operations to the client via
-// FileSystemCallbackDispatcher.
-// TODO(kinuko): Change the functions to take callbacks instead.
+// 3) Deliver the results of operations to the client via the callback function
+// passed as the last parameter of the method.
 //
 class FileSystemOperationInterface {
  public:
   virtual ~FileSystemOperationInterface() {}
 
+  // Used for CreateFile(), etc. |result| is the return code of the operation.
+  typedef base::Callback<void(base::PlatformFileError result)> StatusCallback;
+
+  // Used for GetMetadata(). |result| is the return code of the operation,
+  // |file_info| is the obtained file info, and |platform_path| is the path
+  // of the file.
+  typedef base::Callback<void(
+      base::PlatformFileError result,
+      const base::PlatformFileInfo& file_info,
+      const FilePath& platform_path)> GetMetadataCallback;
+
+  // Used for OpenFile(). |result| is the return code of the operation.
+  typedef base::Callback<void(
+      base::PlatformFileError result,
+      base::PlatformFile file,
+      base::ProcessHandle peer_handle)> OpenFileCallback;
+
+  // Used for ReadDirectory(). |result| is the return code of the operation,
+  // |file_list| is the list of files read, and |has_more| is true if some files
+  // are yet to be read.
+  typedef base::Callback<void(
+      base::PlatformFileError result,
+      const std::vector<base::FileUtilProxy::Entry>& file_list,
+      bool has_more)> ReadDirectoryCallback;
+
+  // Used for Write().
+  typedef base::Callback<void(base::PlatformFileError result,
+                              int64 bytes,
+                              bool complete)> WriteCallback;
+
   // Creates a file at |path|. If |exclusive| is true, an error is raised
   // in case a file is already present at the URL.
   virtual void CreateFile(const GURL& path,
-                          bool exclusive) = 0;
+                          bool exclusive,
+                          const StatusCallback& callback) = 0;
 
   // Creates a directory at |path|. If |exclusive| is true, an error is
   // raised in case a directory is already present at the URL. If
   // |recursive| is true, create parent directories as needed just like
   // mkdir -p does.
   virtual void CreateDirectory(const GURL& path,
                                bool exclusive,
-                               bool recursive) = 0;
+                               bool recursive,
+                               const StatusCallback& callback) = 0;
 
   // Copes a file or directory from |src_path| to |dest_path|. If
   // |src_path| is a directory, the contents of |src_path| are copied to
   // |dest_path| recursively. A new file or directory is created at
   // |dest_path| as needed.
   virtual void Copy(const GURL& src_path,
-                    const GURL& dest_path) = 0;
+                    const GURL& dest_path,
+                    const StatusCallback& callback) = 0;
 
   // Moves a file or directory from |src_path| to |dest_path|. A new file
   // or directory is created at |dest_path| as needed.
   virtual void Move(const GURL& src_path,
-                    const GURL& dest_path) = 0;
+                    const GURL& dest_path,
+                    const StatusCallback& callback) = 0;
 
   // Checks if a directory is present at |path|.
-  virtual void DirectoryExists(const GURL& path) = 0;
+  virtual void DirectoryExists(const GURL& path,
+                               const StatusCallback& callback) = 0;
 
   // Checks if a file is present at |path|.
-  virtual void FileExists(const GURL& path) = 0;
+  virtual void FileExists(const GURL& path,
+                          const StatusCallback& callback) = 0;
 
   // Gets the metadata of a file or directory at |path|.
-  virtual void GetMetadata(const GURL& path) = 0;
+  virtual void GetMetadata(const GURL& path,
+                           const GetMetadataCallback& callback) = 0;
 
   // Reads contents of a directory at |path|.
-  virtual void ReadDirectory(const GURL& path) = 0;
+  virtual void ReadDirectory(const GURL& path,
+                             const ReadDirectoryCallback& callback) = 0;
 
   // Removes a file or directory at |path|. If |recursive| is true, remove
   // all files and directories under the directory at |path| recursively.
-  virtual void Remove(const GURL& path, bool recursive) = 0;
+  virtual void Remove(const GURL& path, bool recursive,
+                      const StatusCallback& callback) = 0;
 
   // Writes contents of |blob_url| to |path| at |offset|.
   // |url_request_context| is used to read contents in |blob_url|.
   virtual void Write(const net::URLRequestContext* url_request_context,
                      const GURL& path,
                      const GURL& blob_url,
-                     int64 offset) = 0;
+                     int64 offset,
+                     const WriteCallback& callback) = 0;
 
   // Truncates a file at |path| to |length|. If |length| is larger than
   // the original file size, the file will be extended, and the extended
   // part is filled with null bytes.
-  virtual void Truncate(const GURL& path, int64 length) = 0;
+  virtual void Truncate(const GURL& path, int64 length,
+                        const StatusCallback& callback) = 0;
 
   // Tries to cancel the current operation [we support cancelling write or
   // truncate only]. Reports failure for the current operation, then reports
   // success for the cancel operation itself via the |cancel_dispatcher|.
   //
   // E.g. a typical cancel implementation would look like:
   //
   //   virtual void SomeOperationImpl::Cancel(
-  //       scoped_ptr<FileSystemCallbackDispatcher> cancel_dispatcher) {
+  //       const StatusCallback& cancel_callback) {
   //     // Abort the current inflight operation first.
   //     ...
   //
-  //     // Dispatch ABORT error for the current operation by calling
-  //     // DidFail() callback of the dispatcher attached to this operation.
-  //     // (dispatcher_ in this example)
-  //     dispatcher_->DidFail(base::PLATFORM_FILE_ERROR_ABORT);
+  //     // Dispatch ABORT error for the current operation by invoking
+  //     // the callback function attached to this operation.

[kinuko, 2012/02/10 05:34:09]

"by invoking the callback function for the ongoing operation" ?

Can we also note that for cancellable operations the operation needs to keep the
callback around?

[kinaba, 2012/02/10 08:22:58]

Done.

+  //     operation_callback.Run(base::PLATFORM_FILE_ERROR_ABORT, ...);

[kinuko, 2012/02/10 05:34:09]

Can you briefly note that what this operation_callback is supposed to be?

(e.g. maybe we could revise the above comment "for the ongoing operation,
operation_callback_ in this code example")

[kinaba, 2012/02/10 08:22:58]

Done.

   //
   //     // Dispatch 'success' for the cancel (or dispatch appropriate
   //     // error code with DidFail() if the cancel has somehow failed).
-  //     cancel_dispatcher->DidSucceed();
+  //     cancel_callback.Run(base::PLATFORM_FILE_OK);
   //   }
   //
-  virtual void Cancel(
-      scoped_ptr<FileSystemCallbackDispatcher> cancel_dispatcher) = 0;
+  virtual void Cancel(const StatusCallback& cancel_callback) = 0;
 
   // Modifies timestamps of a file or directory at |path| with
   // |last_access_time| and |last_modified_time|. The function DOES NOT
   // create a file unlike 'touch' command on Linux.
   //
   // This function is used only by Pepper as of writing.
   virtual void TouchFile(const GURL& path,
                          const base::Time& last_access_time,
-                         const base::Time& last_modified_time) = 0;
+                         const base::Time& last_modified_time,
+                         const StatusCallback& callback) = 0;
 
   // Opens a file at |path| with |file_flags|, where flags are OR'ed
   // values of base::PlatformFileFlags.
   //
   // |peer_handle| is the process handle of a pepper plugin process, which
   // is necessary for underlying IPC calls with Pepper plugins.
   //
   // This function is used only by Pepper as of writing.
-  virtual void OpenFile(
-      const GURL& path,
-      int file_flags,
-      base::ProcessHandle peer_handle) = 0;
+  virtual void OpenFile(const GURL& path,
+                        int file_flags,
+                        base::ProcessHandle peer_handle,
+                        const OpenFileCallback& callback) = 0;
 
   // For downcasting to FileSystemOperation.
   // TODO(kinuko): this hack should go away once appropriate upload-stream
   // handling based on element types is supported.
   virtual FileSystemOperation* AsFileSystemOperation() = 0;
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_INTERFACE_H_