[Media Galleries] Filesystem interface for Mac PTP/MTP devices using ImageCaptureCore (part 3)

chrome/browser/media_gallery/mac/mtp_device_delegate_impl_mac.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 CHROME_BROWSER_MEDIA_GALLERY_MTP_DEVICE_DELEGATE_IMPL_MAC_H_
+#define CHROME_BROWSER_MEDIA_GALLERY_MTP_DEVICE_DELEGATE_IMPL_MAC_H_
+
+#include <vector>
+#include "base/file_path.h"
+#include "base/hash_tables.h"
+#include "base/memory/weak_ptr.h"
+#include "base/platform_file.h"
+#include "base/synchronization/waitable_event.h"
+#include "webkit/fileapi/file_system_file_util.h"
+#include "webkit/fileapi/media/mtp_device_delegate.h"
+
+namespace base {
+class SequencedTaskRunner;
+}
+
+namespace chrome {
+
+class CameraDeviceInterface;
+
+// Delegate for presenting an Image Capture device through the filesystem
+// API. The synthetic filesystem will be rooted at the constructed location,
+// and names of non-directories notified through the ItemAdded call will be
+// all appear as children of that directory.
+class MTPDeviceDelegateImplMac : public fileapi::MTPDeviceDelegate {
+ public:
+  MTPDeviceDelegateImplMac(const FilePath::StringType& location,
+                           base::SequencedTaskRunner* media_task_runner);
+  // Destructed via CancelPendingTasksAndDeleteDelegate. Do not call directly.
+  virtual ~MTPDeviceDelegateImplMac();
+
+  // MTPDeviceDelegate:
+  virtual base::PlatformFileError GetFileInfo(
+      const FilePath& file_path,
+      base::PlatformFileInfo* file_info) OVERRIDE;
+  virtual scoped_ptr<fileapi::FileSystemFileUtil::AbstractFileEnumerator>
+      CreateFileEnumerator(const FilePath& root, bool recursive) OVERRIDE;
+  virtual base::PlatformFileError CreateSnapshotFile(
+      const FilePath& device_file_path,
+      const FilePath& local_path,
+      base::PlatformFileInfo* file_info) OVERRIDE;
+  virtual void CancelPendingTasksAndDeleteDelegate() OVERRIDE;
+
+  // Forward delegates for ImageCaptureDeviceListener
+  virtual void ItemAdded(const std::string& name,
+                         const base::PlatformFileInfo& info);
+  virtual void NoMoreItems();
+  virtual void DownloadedFile(const std::string& name,
+                              base::PlatformFileError error);
+
+  // Implementation returned by |CreateFileEnumerator()|. Must be deleted
+  // before CancelPendingTeasksAndDeleteDelegate is called.

[Lei Zhang, 2012/12/22 02:44:35]

typo

[Greg Billock, 2012/12/22 03:11:41]

Done.

+  class Enumerator :
+      public fileapi::FileSystemFileUtil::AbstractFileEnumerator {
+   public:
+    explicit Enumerator(MTPDeviceDelegateImplMac* delegate);
+    virtual ~Enumerator();
+
+    virtual FilePath Next() OVERRIDE;
+    virtual int64 Size() OVERRIDE;
+    virtual base::Time LastModifiedTime() OVERRIDE;
+    virtual bool IsDirectory() OVERRIDE;
+
+    // Called by the delegate to signal any waiters that the received items
+    // list has changed state.
+    void ItemsChanged();
+
+   private:
+    MTPDeviceDelegateImplMac* delegate_;
+    size_t position_;
+    base::WaitableEvent wait_for_items_;
+  };
+
+  // GetFile and HasAllFiles called by enumerators.
+  FilePath GetFile(size_t index);
+  bool HasAllFiles();
+  void RemoveEnumerator(Enumerator* enumerator);
+
+ private:
+  std::string device_id_;
+  FilePath root_path_;
+
+  // Stores a reference to worker pool thread. All requests and response of file
+  // operations are posted on |media_task_runner_|. All callbacks from the
+  // camera will come through this task runner as well.
+  scoped_refptr<base::SequencedTaskRunner> media_task_runner_;
+
+  // Interface object for the camera underlying this MTP session.
+  scoped_ptr<CameraDeviceInterface> camera_interface_;
+
+  // Stores a map from filename to file metadata received from the camera.
+  base::hash_map<FilePath::StringType, base::PlatformFileInfo> file_info_;
+
+  // Notifications for all the files we're waiting on downloads for.
+  base::hash_map<std::string, base::WaitableEvent*> download_events_;
+
+  // Resulting error codes for downloads.
+  base::hash_map<std::string, base::PlatformFileError> download_errors_;
+
+  // List of files received from the camera.
+  std::vector<FilePath::StringType> file_paths_;
+
+  // List of enumerators which may be listening for files to come in.
+  std::vector<Enumerator*> enumerators_;

[Lei Zhang, 2012/12/22 02:44:35]

I don't think we'll have multiple enumerators. Also, enumerators tend to get
iterated through all the way right after being created. Thus they'll be blocked
waiting for device entries no matter what.

Given this, would it simplify the implementation to just get the entire list of
files when creating the enumerator?

[Greg Billock, 2012/12/22 03:11:41]

Oh, that does simplify things. I'll assume that.

On 2012/12/22 02:44:35, Lei Zhang wrote:
The way I'm implementing it, the caller is free to start working with the files
even before all of them are known. For cards with a lot of files, that's really
nice -- the first ones come in, and you can download them while the other 1000
load, which can take a couple of minutes, in my experience. So I'll keep the
blocking behavior, but I can definitely simplify the notification logic with
only one iteration going on.

+
+  // Set to true when all file metadata has been received from the camera.
+  bool received_all_files_;
+
+  DISALLOW_COPY_AND_ASSIGN(MTPDeviceDelegateImplMac);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_MEDIA_GALLERY_MTP_DEVICE_DELEGATE_IMPL_MAC_H_