chrome/browser/resources/file_manager/foreground/js/file_watcher.js

   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 'use strict';
   6
   7 /**
   8  * Watches for changes in the tracked directory, including local metadata
   9  * changes.
  10  *
  11  * @param {MetadataCache} metadataCache Instance of MetadataCache.
  12  * @extends {cr.EventTarget}
  13  * @constructor
  14  */
  15 function FileWatcher(metadataCache) {
  16   this.queue_ = new AsyncUtil.Queue();
  17   this.metadataCache_ = metadataCache;
  18   this.watchedDirectoryEntry_ = null;
  19
  20   this.onDirectoryChangedBound_ = this.onDirectoryChanged_.bind(this);
  21   chrome.fileBrowserPrivate.onDirectoryChanged.addListener(
  22       this.onDirectoryChangedBound_);
  23
  24   this.filesystemMetadataObserverId_ = null;
  25   this.thumbnailMetadataObserverId_ = null;
  26   this.driveMetadataObserverId_ = null;
  27 }
  28
  29 /**
  30  * FileWatcher extends cr.EventTarget.
  31  */
  32 FileWatcher.prototype.__proto__ = cr.EventTarget.prototype;
  33
  34 /**
  35  * Stops watching (must be called before page unload).
  36  */
  37 FileWatcher.prototype.dispose = function() {
  38   chrome.fileBrowserPrivate.onDirectoryChanged.removeListener(
  39       this.onDirectoryChangedBound_);
  40   if (this.watchedDirectoryEntry_)
  41     this.resetWatchedEntry_(function() {}, function() {});
  42 };
  43
  44 /**
  45  * Called when a file in the watched directory is changed.
  46  * @param {Event} event Change event.
  47  * @private
  48  */
  49 FileWatcher.prototype.onDirectoryChanged_ = function(event) {
  50   if (this.watchedDirectoryEntry_ &&
  51       event.entry.toURL() === this.watchedDirectoryEntry_.toURL()) {
  52     var e = new Event('watcher-directory-changed');
  53     this.dispatchEvent(e);
  54   }
  55 };
  56
  57 /**
  58  * Called when general metadata in the watched directory has been changed.
  59  *
  60  * @param {Array.<string>} urls Array of urls.
  61  * @param {Object.<string, Object>} properties Map from entry URLs to metadata
  62  *     properties.
  63  * @private
  64  */
  65 FileWatcher.prototype.onFilesystemMetadataChanged_ = function(
  66     urls, properties) {
  67   this.dispatchMetadataEvent_('filesystem', urls, properties);
  68 };
  69
  70 /**
  71  * Called when thumbnail metadata in the watched directory has been changed.
  72  *
  73  * @param {Array.<string>} urls Array of urls.
  74  * @param {Object.<string, Object>} properties Map from entry URLs to metadata
  75  *     properties.
  76  * @private
  77  */
  78 FileWatcher.prototype.onThumbnailMetadataChanged_ = function(
  79     urls, properties) {
  80   this.dispatchMetadataEvent_('thumbnail', urls, properties);
  81 };
  82
  83 /**
  84  * Called when drive metadata in the watched directory has been changed.
  85  *
  86  * @param {Array.<string>} urls Array of urls.
  87  * @param {Object.<string, Object>} properties Map from entry URLs to metadata
  88  *     properties.
  89  * @private
  90  */
  91 FileWatcher.prototype.onDriveMetadataChanged_ = function(
  92     urls, properties) {
  93   this.dispatchMetadataEvent_('drive', urls, properties);
  94 };
  95
  96 /**
  97  * Dispatches an event about detected change in metadata within the tracked
  98  * directory.
  99  *
 100  * @param {string} type Type of the metadata change.
 101  * @param {Array.<string>} urls Array of urls.
 102  * @param {Object.<string, Object>} properties Map from entry URLs to metadata
 103  *     properties.
 104  * @private
 105  */
 106 FileWatcher.prototype.dispatchMetadataEvent_ = function(
 107     type, urls, properties) {
 108   var e = new Event('watcher-metadata-changed');
 109   e.metadataType = type;
 110   e.urls = urls;
 111   e.properties = properties;
 112   this.dispatchEvent(e);
 113 };
 114
 115 /**
 116  * Changes the watched directory. In case of a fake entry, the watch is
 117  * just released, since there is no reason to track a fake directory.
 118  *
 119  * @param {!DirectoryEntry|!Object} entry Directory entry to be tracked, or the
 120  *     fake entry.
 121  * @param {function()} callback Completion callback.
 122  */
 123 FileWatcher.prototype.changeWatchedDirectory = function(entry, callback) {
 124   if (entry && entry.toURL) {
 125     this.changeWatchedEntry_(
 126         entry,
 127         callback,
 128         function() {
 129           console.error(
 130              'Unable to change the watched directory to: ' + entry.toURL());
 131           callback();
 132         });
 133   } else {
 134     this.resetWatchedEntry_(
 135         callback,
 136         function() {
 137           console.error('Unable to reset the watched directory.');
 138           callback();
 139         });
 140   }
 141 };
 142
 143 /**
 144  * Resets the watched entry to the passed directory.
 145  *
 146  * @param {function()} onSuccess Success callback.
 147  * @param {function()} onError Error callback.
 148  * @private
 149  */
 150 FileWatcher.prototype.resetWatchedEntry_ = function(onSuccess, onError) {
 151   // Run the tasks in the queue to avoid races.
 152   this.queue_.run(function(callback) {
 153     // Release the watched directory.
 154     if (this.watchedDirectoryEntry_) {
 155       chrome.fileBrowserPrivate.removeFileWatch(
 156           this.watchedDirectoryEntry_.toURL(),
 157           function(result) {
 158             this.watchedDirectoryEntry_ = null;
 159             if (result)
 160               onSuccess();
 161             else
 162               onError();
 163             callback();
 164           }.bind(this));
 165       this.metadataCache_.removeObserver(this.filesystemMetadataObserverId_);
 166       this.metadataCache_.removeObserver(this.thumbnailMetadataObserverId_);
 167       this.metadataCache_.removeObserver(this.driveMetadataObserverId_);
 168     } else {
 169       onSuccess();
 170       callback();
 171     }
 172   }.bind(this));
 173 };
 174
 175 /**
 176  * Sets the watched entry to the passed directory.
 177  *
 178  * @param {!DirectoryEntry} entry Directory to be watched.
 179  * @param {function()} onSuccess Success callback.
 180  * @param {function()} onError Error callback.
 181  * @private
 182  */
 183 FileWatcher.prototype.changeWatchedEntry_ = function(
 184     entry, onSuccess, onError) {
 185   var setEntryClosure = function() {
 186     // Run the tasks in the queue to avoid races.
 187     this.queue_.run(function(callback) {
 188       chrome.fileBrowserPrivate.addFileWatch(
 189           entry.toURL(),
 190           function(result) {
 191             if (!result) {
 192               this.watchedDirectoryEntry_ = null;
 193               onError();
 194             } else {
 195               this.watchedDirectoryEntry_ = entry;
 196               onSuccess();
 197             }
 198             callback();
 199           }.bind(this));
 200       this.filesystemMetadataObserverId_ = this.metadataCache_.addObserver(
 201         entry,
 202         MetadataCache.CHILDREN,
 203         'filesystem',
 204         this.onFilesystemMetadataChanged_.bind(this));
 205       this.thumbnailMetadataObserverId_ = this.metadataCache_.addObserver(
 206         entry,
 207         MetadataCache.CHILDREN,
 208         'thumbnail',
 209         this.onThumbnailMetadataChanged_.bind(this));
 210       this.driveMetadataObserverId_ = this.metadataCache_.addObserver(
 211         entry,
 212         MetadataCache.CHILDREN,
 213         'drive',
 214         this.onDriveMetadataChanged_.bind(this));
 215     }.bind(this));
 216   }.bind(this);
 217
 218   // Reset the watched directory first, then set the new watched directory.
 219   this.resetWatchedEntry_(setEntryClosure, onError);
 220 };
 221
 222 /**
 223  * @return {DirectoryEntry} Current watched directory entry.
 224  */
 225 FileWatcher.prototype.getWatchedDirectoryEntry = function() {
 226   return this.watchedDirectoryEntry_;
 227 };