chrome/browser/media_galleries/fileapi/file_path_watcher_util.cc

   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 #include "chrome/browser/media_galleries/fileapi/file_path_watcher_util.h"
   6
   7 #include "base/bind.h"
   8 #include "base/callback.h"
   9 #include "base/location.h"
  10 #include "base/logging.h"
  11 #include "chrome/browser/media_galleries/fileapi/media_file_system_backend.h"
  12 #include "content/public/browser/browser_thread.h"
  13
  14 namespace {
  15
  16 // Bounces |path| and |error| to |callback| from the FILE thread to the media
  17 // task runner.
  18 void OnFilePathChangedOnFileThread(
  19     const base::FilePathWatcher::Callback& callback,
  20     const base::FilePath& path,
  21     bool error) {
  22   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  23   MediaFileSystemBackend::MediaTaskRunner()->PostTask(
  24       FROM_HERE, base::Bind(callback, path, error));
  25 }
  26
  27 // The watch has to be started on the FILE thread, and the callback called by
  28 // the FilePathWatcher also needs to run on the FILE thread.
  29 void StartFilePathWatchOnFileThread(
  30     const base::FilePath& path,
  31     const FileWatchStartedCallback& watch_started_callback,
  32     const base::FilePathWatcher::Callback& path_changed_callback) {
  33   DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
  34   // The watcher is created on the FILE thread because it is very difficult
  35   // to safely pass an already-created file watcher to a different thread.
  36   scoped_ptr<base::FilePathWatcher> watcher(new base::FilePathWatcher);
  37   bool success = watcher->Watch(
  38       path,
  39       false /* recursive */,
  40       base::Bind(&OnFilePathChangedOnFileThread, path_changed_callback));
  41   if (!success)
  42     LOG(ERROR) << "Adding watch for " << path.value() << " failed";
  43   MediaFileSystemBackend::MediaTaskRunner()->PostTask(
  44       FROM_HERE, base::Bind(watch_started_callback, base::Passed(&watcher)));
  45 }
  46
  47 }  // namespace
  48
  49 void StartFilePathWatchOnMediaTaskRunner(
  50     const base::FilePath& path,
  51     const FileWatchStartedCallback& watch_started_callback,
  52     const base::FilePathWatcher::Callback& path_changed_callback) {
  53   DCHECK(MediaFileSystemBackend::CurrentlyOnMediaTaskRunnerThread());
  54   content::BrowserThread::PostTask(content::BrowserThread::FILE,
  55                                    FROM_HERE,
  56                                    base::Bind(&StartFilePathWatchOnFileThread,
  57                                               path,
  58                                               watch_started_callback,
  59                                               path_changed_callback));
  60 }