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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
      6 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
      7 
      8 #include "base/callback_forward.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/memory/weak_ptr.h"
     11 #include "chrome/browser/chromeos/drive/file_system_util.h"
     12 
     13 namespace base {
     14 class FilePath;
     15 }  // namespace base
     16 
     17 namespace drive {
     18 
     19 namespace file_system {
     20 class OperationObserver;
     21 }  // namespace file_system
     22 
     23 namespace internal {
     24 
     25 typedef base::Callback<void(bool)> StartWatchCallback;
     26 
     27 // The class watches modification to Drive files in the cache directory.
     28 // This is used for returning a local writable snapshot of Drive files from the
     29 // Save-As file dialog, so that the callers of the dialog can save to Drive
     30 // without any special handling about Drive.
     31 class FileWriteWatcher {
     32  public:
     33   explicit FileWriteWatcher(file_system::OperationObserver* observer);
     34   ~FileWriteWatcher();
     35 
     36   // Starts watching the modification to |path|. When it successfully started
     37   // watching, it runs |callback| by passing true as the argument. Or if it
     38   // failed, the callback is run with false.
     39   // When modification is detected, it is notified to the |observer| passed to
     40   // the constructor by calling OnCacheFileUploadNeededByOperation(resource_id).
     41   //
     42   // Currently, the modification is watched in "one-shot" manner. That is, once
     43   // a modification is notified, the watch is deactivated for freeing system
     44   // resources. As a heuristic to capture the real end of write operations that
     45   // might be done by several chunked writes, the notification is fired after
     46   // 5 seconds has passed after the last write operation is detected.
     47   //
     48   // TODO(kinaba): investigate the possibility to continuously watch the whole
     49   // cache directory. http://crbug.com/269424
     50   void StartWatch(const base::FilePath& path,
     51                   const std::string& resource_id,
     52                   const StartWatchCallback& callback);
     53 
     54   // For testing purpose, stops inserting delay between the write detection and
     55   // notification to the observer.
     56   void DisableDelayForTesting();
     57 
     58  private:
     59   // Invoked when a modification is observed.
     60   void OnWriteEvent(const std::string& resource_id);
     61 
     62   class FileWriteWatcherImpl;
     63   scoped_ptr<FileWriteWatcherImpl, util::DestroyHelper> watcher_impl_;
     64   file_system::OperationObserver* operation_observer_;
     65 
     66   // Note: This should remain the last member so it'll be destroyed and
     67   // invalidate its weak pointers before any other members are destroyed.
     68   base::WeakPtrFactory<FileWriteWatcher> weak_ptr_factory_;
     69   DISALLOW_COPY_AND_ASSIGN(FileWriteWatcher);
     70 };
     71 
     72 }  // namespace internal
     73 }  // namespace drive
     74 
     75 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
     76