michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["PageThumbs", "PageThumbsStorage"];
michael@0: 
michael@0: const Cu = Components.utils;
michael@0: const Cc = Components.classes;
michael@0: const Ci = Components.interfaces;
michael@0: 
michael@0: const HTML_NAMESPACE = "http://www.w3.org/1999/xhtml";
michael@0: const PREF_STORAGE_VERSION = "browser.pagethumbnails.storage_version";
michael@0: const LATEST_STORAGE_VERSION = 3;
michael@0: 
michael@0: const EXPIRATION_MIN_CHUNK_SIZE = 50;
michael@0: const EXPIRATION_INTERVAL_SECS = 3600;
michael@0: 
michael@0: // If a request for a thumbnail comes in and we find one that is "stale"
michael@0: // (or don't find one at all) we automatically queue a request to generate a
michael@0: // new one.
michael@0: const MAX_THUMBNAIL_AGE_SECS = 172800; // 2 days == 60*60*24*2 == 172800 secs.
michael@0: 
michael@0: /**
michael@0:  * Name of the directory in the profile that contains the thumbnails.
michael@0:  */
michael@0: const THUMBNAIL_DIRECTORY = "thumbnails";
michael@0: 
michael@0: /**
michael@0:  * The default background color for page thumbnails.
michael@0:  */
michael@0: const THUMBNAIL_BG_COLOR = "#fff";
michael@0: 
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
michael@0: Cu.import("resource://gre/modules/osfile/_PromiseWorker.jsm", this);
michael@0: Cu.import("resource://gre/modules/Promise.jsm", this);
michael@0: Cu.import("resource://gre/modules/osfile.jsm", this);
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
michael@0:   "resource://gre/modules/NetUtil.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "Services",
michael@0:   "resource://gre/modules/Services.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
michael@0:   "resource://gre/modules/FileUtils.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
michael@0:   "resource://gre/modules/PlacesUtils.jsm");
michael@0: 
michael@0: XPCOMUtils.defineLazyServiceGetter(this, "gUpdateTimerManager",
michael@0:   "@mozilla.org/updates/timer-manager;1", "nsIUpdateTimerManager");
michael@0: 
michael@0: XPCOMUtils.defineLazyGetter(this, "gCryptoHash", function () {
michael@0:   return Cc["@mozilla.org/security/hash;1"].createInstance(Ci.nsICryptoHash);
michael@0: });
michael@0: 
michael@0: XPCOMUtils.defineLazyGetter(this, "gUnicodeConverter", function () {
michael@0:   let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
michael@0:                     .createInstance(Ci.nsIScriptableUnicodeConverter);
michael@0:   converter.charset = 'utf8';
michael@0:   return converter;
michael@0: });
michael@0: 
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "Task",
michael@0:   "resource://gre/modules/Task.jsm");
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "Deprecated",
michael@0:   "resource://gre/modules/Deprecated.jsm");
michael@0: XPCOMUtils.defineLazyModuleGetter(this, "AsyncShutdown",
michael@0:   "resource://gre/modules/AsyncShutdown.jsm");
michael@0: 
michael@0: /**
michael@0:  * Utilities for dealing with promises and Task.jsm
michael@0:  */
michael@0: const TaskUtils = {
michael@0:   /**
michael@0:    * Add logging to a promise.
michael@0:    *
michael@0:    * @param {Promise} promise
michael@0:    * @return {Promise} A promise behaving as |promise|, but with additional
michael@0:    * logging in case of uncaught error.
michael@0:    */
michael@0:   captureErrors: function captureErrors(promise) {
michael@0:     return promise.then(
michael@0:       null,
michael@0:       function onError(reason) {
michael@0:         Cu.reportError("Uncaught asynchronous error: " + reason + " at\n"
michael@0:           + reason.stack + "\n");
michael@0:         throw reason;
michael@0:       }
michael@0:     );
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Spawn a new Task from a generator.
michael@0:    *
michael@0:    * This function behaves as |Task.spawn|, with the exception that it
michael@0:    * adds logging in case of uncaught error. For more information, see
michael@0:    * the documentation of |Task.jsm|.
michael@0:    *
michael@0:    * @param {generator} gen Some generator.
michael@0:    * @return {Promise} A promise built from |gen|, with the same semantics
michael@0:    * as |Task.spawn(gen)|.
michael@0:    */
michael@0:   spawn: function spawn(gen) {
michael@0:     return this.captureErrors(Task.spawn(gen));
michael@0:   },
michael@0:   /**
michael@0:    * Read the bytes from a blob, asynchronously.
michael@0:    *
michael@0:    * @return {Promise}
michael@0:    * @resolve {ArrayBuffer} In case of success, the bytes contained in the blob.
michael@0:    * @reject {DOMError} In case of error, the underlying DOMError.
michael@0:    */
michael@0:   readBlob: function readBlob(blob) {
michael@0:     let deferred = Promise.defer();
michael@0:     let reader = Cc["@mozilla.org/files/filereader;1"].createInstance(Ci.nsIDOMFileReader);
michael@0:     reader.onloadend = function onloadend() {
michael@0:       if (reader.readyState != Ci.nsIDOMFileReader.DONE) {
michael@0:         deferred.reject(reader.error);
michael@0:       } else {
michael@0:         deferred.resolve(reader.result);
michael@0:       }
michael@0:     };
michael@0:     reader.readAsArrayBuffer(blob);
michael@0:     return deferred.promise;
michael@0:   }
michael@0: };
michael@0: 
michael@0: 
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Singleton providing functionality for capturing web page thumbnails and for
michael@0:  * accessing them if already cached.
michael@0:  */
michael@0: this.PageThumbs = {
michael@0:   _initialized: false,
michael@0: 
michael@0:   /**
michael@0:    * The calculated width and height of the thumbnails.
michael@0:    */
michael@0:   _thumbnailWidth : 0,
michael@0:   _thumbnailHeight : 0,
michael@0: 
michael@0:   /**
michael@0:    * The scheme to use for thumbnail urls.
michael@0:    */
michael@0:   get scheme() "moz-page-thumb",
michael@0: 
michael@0:   /**
michael@0:    * The static host to use for thumbnail urls.
michael@0:    */
michael@0:   get staticHost() "thumbnail",
michael@0: 
michael@0:   /**
michael@0:    * The thumbnails' image type.
michael@0:    */
michael@0:   get contentType() "image/png",
michael@0: 
michael@0:   init: function PageThumbs_init() {
michael@0:     if (!this._initialized) {
michael@0:       this._initialized = true;
michael@0:       PlacesUtils.history.addObserver(PageThumbsHistoryObserver, false);
michael@0: 
michael@0:       // Migrate the underlying storage, if needed.
michael@0:       PageThumbsStorageMigrator.migrate();
michael@0:       PageThumbsExpiration.init();
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   uninit: function PageThumbs_uninit() {
michael@0:     if (this._initialized) {
michael@0:       this._initialized = false;
michael@0:       PlacesUtils.history.removeObserver(PageThumbsHistoryObserver);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Gets the thumbnail image's url for a given web page's url.
michael@0:    * @param aUrl The web page's url that is depicted in the thumbnail.
michael@0:    * @return The thumbnail image's url.
michael@0:    */
michael@0:   getThumbnailURL: function PageThumbs_getThumbnailURL(aUrl) {
michael@0:     return this.scheme + "://" + this.staticHost +
michael@0:            "?url=" + encodeURIComponent(aUrl);
michael@0:   },
michael@0: 
michael@0:    /**
michael@0:     * Gets the path of the thumbnail file for a given web page's
michael@0:     * url. This file may or may not exist depending on whether the
michael@0:     * thumbnail has been captured or not.
michael@0:     *
michael@0:     * @param aUrl The web page's url.
michael@0:     * @return The path of the thumbnail file.
michael@0:     */
michael@0:    getThumbnailPath: function PageThumbs_getThumbnailPath(aUrl) {
michael@0:      return PageThumbsStorage.getFilePathForURL(aUrl);
michael@0:    },
michael@0: 
michael@0:   /**
michael@0:    * Captures a thumbnail for the given window.
michael@0:    * @param aWindow The DOM window to capture a thumbnail from.
michael@0:    * @param aCallback The function to be called when the thumbnail has been
michael@0:    *                  captured. The first argument will be the data stream
michael@0:    *                  containing the image data.
michael@0:    */
michael@0:   capture: function PageThumbs_capture(aWindow, aCallback) {
michael@0:     if (!this._prefEnabled()) {
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     let canvas = this._createCanvas();
michael@0:     this.captureToCanvas(aWindow, canvas);
michael@0: 
michael@0:     // Fetch the canvas data on the next event loop tick so that we allow
michael@0:     // some event processing in between drawing to the canvas and encoding
michael@0:     // its data. We want to block the UI as short as possible. See bug 744100.
michael@0:     Services.tm.currentThread.dispatch(function () {
michael@0:       canvas.mozFetchAsStream(aCallback, this.contentType);
michael@0:     }.bind(this), Ci.nsIThread.DISPATCH_NORMAL);
michael@0:   },
michael@0: 
michael@0: 
michael@0:   /**
michael@0:    * Captures a thumbnail for the given window.
michael@0:    *
michael@0:    * @param aWindow The DOM window to capture a thumbnail from.
michael@0:    * @return {Promise}
michael@0:    * @resolve {Blob} The thumbnail, as a Blob.
michael@0:    */
michael@0:   captureToBlob: function PageThumbs_captureToBlob(aWindow) {
michael@0:     if (!this._prefEnabled()) {
michael@0:       return null;
michael@0:     }
michael@0: 
michael@0:     let canvas = this._createCanvas();
michael@0:     this.captureToCanvas(aWindow, canvas);
michael@0: 
michael@0:     let deferred = Promise.defer();
michael@0:     let type = this.contentType;
michael@0:     // Fetch the canvas data on the next event loop tick so that we allow
michael@0:     // some event processing in between drawing to the canvas and encoding
michael@0:     // its data. We want to block the UI as short as possible. See bug 744100.
michael@0:     canvas.toBlob(function asBlob(blob) {
michael@0:       deferred.resolve(blob, type);
michael@0:     });
michael@0:     return deferred.promise;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Captures a thumbnail from a given window and draws it to the given canvas.
michael@0:    * @param aWindow The DOM window to capture a thumbnail from.
michael@0:    * @param aCanvas The canvas to draw to.
michael@0:    */
michael@0:   captureToCanvas: function PageThumbs_captureToCanvas(aWindow, aCanvas) {
michael@0:     let telemetryCaptureTime = new Date();
michael@0:     this._captureToCanvas(aWindow, aCanvas);
michael@0:     let telemetry = Services.telemetry;
michael@0:     telemetry.getHistogramById("FX_THUMBNAILS_CAPTURE_TIME_MS")
michael@0:       .add(new Date() - telemetryCaptureTime);
michael@0:   },
michael@0: 
michael@0:   // The background thumbnail service captures to canvas but doesn't want to
michael@0:   // participate in this service's telemetry, which is why this method exists.
michael@0:   _captureToCanvas: function PageThumbs__captureToCanvas(aWindow, aCanvas) {
michael@0:     let [sw, sh, scale] = this._determineCropSize(aWindow, aCanvas);
michael@0:     let ctx = aCanvas.getContext("2d");
michael@0: 
michael@0:     // Scale the canvas accordingly.
michael@0:     ctx.save();
michael@0:     ctx.scale(scale, scale);
michael@0: 
michael@0:     try {
michael@0:       // Draw the window contents to the canvas.
michael@0:       ctx.drawWindow(aWindow, 0, 0, sw, sh, THUMBNAIL_BG_COLOR,
michael@0:                      ctx.DRAWWINDOW_DO_NOT_FLUSH);
michael@0:     } catch (e) {
michael@0:       // We couldn't draw to the canvas for some reason.
michael@0:     }
michael@0: 
michael@0:     ctx.restore();
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Captures a thumbnail for the given browser and stores it to the cache.
michael@0:    * @param aBrowser The browser to capture a thumbnail for.
michael@0:    * @param aCallback The function to be called when finished (optional).
michael@0:    */
michael@0:   captureAndStore: function PageThumbs_captureAndStore(aBrowser, aCallback) {
michael@0:     if (!this._prefEnabled()) {
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     let url = aBrowser.currentURI.spec;
michael@0:     let channel = aBrowser.docShell.currentDocumentChannel;
michael@0:     let originalURL = channel.originalURI.spec;
michael@0: 
michael@0:     // see if this was an error response.
michael@0:     let wasError = this._isChannelErrorResponse(channel);
michael@0: 
michael@0:     TaskUtils.spawn((function task() {
michael@0:       let isSuccess = true;
michael@0:       try {
michael@0:         let blob = yield this.captureToBlob(aBrowser.contentWindow);
michael@0:         let buffer = yield TaskUtils.readBlob(blob);
michael@0:         yield this._store(originalURL, url, buffer, wasError);
michael@0:       } catch (_) {
michael@0:         isSuccess = false;
michael@0:       }
michael@0:       if (aCallback) {
michael@0:         aCallback(isSuccess);
michael@0:       }
michael@0:     }).bind(this));
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Checks if an existing thumbnail for the specified URL is either missing
michael@0:    * or stale, and if so, captures and stores it.  Once the thumbnail is stored,
michael@0:    * an observer service notification will be sent, so consumers should observe
michael@0:    * such notifications if they want to be notified of an updated thumbnail.
michael@0:    *
michael@0:    * @param aBrowser The content window of this browser will be captured.
michael@0:    * @param aCallback The function to be called when finished (optional).
michael@0:    */
michael@0:   captureAndStoreIfStale: function PageThumbs_captureAndStoreIfStale(aBrowser, aCallback) {
michael@0:     let url = aBrowser.currentURI.spec;
michael@0:     PageThumbsStorage.isFileRecentForURL(url).then(recent => {
michael@0:       if (!recent.ok &&
michael@0:           // Careful, the call to PageThumbsStorage is async, so the browser may
michael@0:           // have navigated away from the URL or even closed.
michael@0:           aBrowser.currentURI &&
michael@0:           aBrowser.currentURI.spec == url) {
michael@0:         this.captureAndStore(aBrowser, aCallback);
michael@0:       } else if (aCallback) {
michael@0:         aCallback(true);
michael@0:       }
michael@0:     }, err => {
michael@0:       if (aCallback)
michael@0:         aCallback(false);
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Stores data to disk for the given URLs.
michael@0:    *
michael@0:    * NB: The background thumbnail service calls this, too.
michael@0:    *
michael@0:    * @param aOriginalURL The URL with which the capture was initiated.
michael@0:    * @param aFinalURL The URL to which aOriginalURL ultimately resolved.
michael@0:    * @param aData An ArrayBuffer containing the image data.
michael@0:    * @param aNoOverwrite If true and files for the URLs already exist, the files
michael@0:    *                     will not be overwritten.
michael@0:    * @return {Promise}
michael@0:    */
michael@0:   _store: function PageThumbs__store(aOriginalURL, aFinalURL, aData, aNoOverwrite) {
michael@0:     return TaskUtils.spawn(function () {
michael@0:       let telemetryStoreTime = new Date();
michael@0:       yield PageThumbsStorage.writeData(aFinalURL, aData, aNoOverwrite);
michael@0:       Services.telemetry.getHistogramById("FX_THUMBNAILS_STORE_TIME_MS")
michael@0:         .add(new Date() - telemetryStoreTime);
michael@0: 
michael@0:       Services.obs.notifyObservers(null, "page-thumbnail:create", aFinalURL);
michael@0:       // We've been redirected. Create a copy of the current thumbnail for
michael@0:       // the redirect source. We need to do this because:
michael@0:       //
michael@0:       // 1) Users can drag any kind of links onto the newtab page. If those
michael@0:       //    links redirect to a different URL then we want to be able to
michael@0:       //    provide thumbnails for both of them.
michael@0:       //
michael@0:       // 2) The newtab page should actually display redirect targets, only.
michael@0:       //    Because of bug 559175 this information can get lost when using
michael@0:       //    Sync and therefore also redirect sources appear on the newtab
michael@0:       //    page. We also want thumbnails for those.
michael@0:       if (aFinalURL != aOriginalURL) {
michael@0:         yield PageThumbsStorage.copy(aFinalURL, aOriginalURL, aNoOverwrite);
michael@0:         Services.obs.notifyObservers(null, "page-thumbnail:create", aOriginalURL);
michael@0:       }
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Register an expiration filter.
michael@0:    *
michael@0:    * When thumbnails are going to expire, each registered filter is asked for a
michael@0:    * list of thumbnails to keep.
michael@0:    *
michael@0:    * The filter (if it is a callable) or its filterForThumbnailExpiration method
michael@0:    * (if the filter is an object) is called with a single argument.  The
michael@0:    * argument is a callback function.  The filter must call the callback
michael@0:    * function and pass it an array of zero or more URLs.  (It may do so
michael@0:    * asynchronously.)  Thumbnails for those URLs will be except from expiration.
michael@0:    *
michael@0:    * @param aFilter callable, or object with filterForThumbnailExpiration method
michael@0:    */
michael@0:   addExpirationFilter: function PageThumbs_addExpirationFilter(aFilter) {
michael@0:     PageThumbsExpiration.addFilter(aFilter);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Unregister an expiration filter.
michael@0:    * @param aFilter A filter that was previously passed to addExpirationFilter.
michael@0:    */
michael@0:   removeExpirationFilter: function PageThumbs_removeExpirationFilter(aFilter) {
michael@0:     PageThumbsExpiration.removeFilter(aFilter);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Determines the crop size for a given content window.
michael@0:    * @param aWindow The content window.
michael@0:    * @param aCanvas The target canvas.
michael@0:    * @return An array containing width, height and scale.
michael@0:    */
michael@0:   _determineCropSize: function PageThumbs_determineCropSize(aWindow, aCanvas) {
michael@0:     let utils = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
michael@0:                        .getInterface(Ci.nsIDOMWindowUtils);
michael@0:     let sbWidth = {}, sbHeight = {};
michael@0: 
michael@0:     try {
michael@0:       utils.getScrollbarSize(false, sbWidth, sbHeight);
michael@0:     } catch (e) {
michael@0:       // This might fail if the window does not have a presShell.
michael@0:       Cu.reportError("Unable to get scrollbar size in _determineCropSize.");
michael@0:       sbWidth.value = sbHeight.value = 0;
michael@0:     }
michael@0: 
michael@0:     // Even in RTL mode, scrollbars are always on the right.
michael@0:     // So there's no need to determine a left offset.
michael@0:     let sw = aWindow.innerWidth - sbWidth.value;
michael@0:     let sh = aWindow.innerHeight - sbHeight.value;
michael@0: 
michael@0:     let {width: thumbnailWidth, height: thumbnailHeight} = aCanvas;
michael@0:     let scale = Math.min(Math.max(thumbnailWidth / sw, thumbnailHeight / sh), 1);
michael@0:     let scaledWidth = sw * scale;
michael@0:     let scaledHeight = sh * scale;
michael@0: 
michael@0:     if (scaledHeight > thumbnailHeight)
michael@0:       sh -= Math.floor(Math.abs(scaledHeight - thumbnailHeight) * scale);
michael@0: 
michael@0:     if (scaledWidth > thumbnailWidth)
michael@0:       sw -= Math.floor(Math.abs(scaledWidth - thumbnailWidth) * scale);
michael@0: 
michael@0:     return [sw, sh, scale];
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Creates a new hidden canvas element.
michael@0:    * @param aWindow The document of this window will be used to create the
michael@0:    *                canvas.  If not given, the hidden window will be used.
michael@0:    * @return The newly created canvas.
michael@0:    */
michael@0:   _createCanvas: function PageThumbs_createCanvas(aWindow) {
michael@0:     let doc = (aWindow || Services.appShell.hiddenDOMWindow).document;
michael@0:     let canvas = doc.createElementNS(HTML_NAMESPACE, "canvas");
michael@0:     canvas.mozOpaque = true;
michael@0:     canvas.mozImageSmoothingEnabled = true;
michael@0:     let [thumbnailWidth, thumbnailHeight] = this._getThumbnailSize();
michael@0:     canvas.width = thumbnailWidth;
michael@0:     canvas.height = thumbnailHeight;
michael@0:     return canvas;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Calculates the thumbnail size based on current desktop's dimensions.
michael@0:    * @return The calculated thumbnail size or a default if unable to calculate.
michael@0:    */
michael@0:   _getThumbnailSize: function PageThumbs_getThumbnailSize() {
michael@0:     if (!this._thumbnailWidth || !this._thumbnailHeight) {
michael@0:       let screenManager = Cc["@mozilla.org/gfx/screenmanager;1"]
michael@0:                             .getService(Ci.nsIScreenManager);
michael@0:       let left = {}, top = {}, width = {}, height = {};
michael@0:       screenManager.primaryScreen.GetRectDisplayPix(left, top, width, height);
michael@0:       this._thumbnailWidth = Math.round(width.value / 3);
michael@0:       this._thumbnailHeight = Math.round(height.value / 3);
michael@0:     }
michael@0:     return [this._thumbnailWidth, this._thumbnailHeight];
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Given a channel, returns true if it should be considered an "error
michael@0:    * response", false otherwise.
michael@0:    */
michael@0:   _isChannelErrorResponse: function(channel) {
michael@0:     // No valid document channel sounds like an error to me!
michael@0:     if (!channel)
michael@0:       return true;
michael@0:     if (!(channel instanceof Ci.nsIHttpChannel))
michael@0:       // it might be FTP etc, so assume it's ok.
michael@0:       return false;
michael@0:     try {
michael@0:       return !channel.requestSucceeded;
michael@0:     } catch (_) {
michael@0:       // not being able to determine success is surely failure!
michael@0:       return true;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   _prefEnabled: function PageThumbs_prefEnabled() {
michael@0:     try {
michael@0:       return !Services.prefs.getBoolPref("browser.pagethumbnails.capturing_disabled");
michael@0:     }
michael@0:     catch (e) {
michael@0:       return true;
michael@0:     }
michael@0:   },
michael@0: };
michael@0: 
michael@0: this.PageThumbsStorage = {
michael@0:   // The path for the storage
michael@0:   _path: null,
michael@0:   get path() {
michael@0:     if (!this._path) {
michael@0:       this._path = OS.Path.join(OS.Constants.Path.localProfileDir, THUMBNAIL_DIRECTORY);
michael@0:     }
michael@0:     return this._path;
michael@0:   },
michael@0: 
michael@0:   ensurePath: function Storage_ensurePath() {
michael@0:     // Create the directory (ignore any error if the directory
michael@0:     // already exists). As all writes are done from the PageThumbsWorker
michael@0:     // thread, which serializes its operations, this ensures that
michael@0:     // future operations can proceed without having to check whether
michael@0:     // the directory exists.
michael@0:     return PageThumbsWorker.post("makeDir",
michael@0:       [this.path, {ignoreExisting: true}]).then(
michael@0:         null,
michael@0:         function onError(aReason) {
michael@0:           Components.utils.reportError("Could not create thumbnails directory" + aReason);
michael@0:         });
michael@0:   },
michael@0: 
michael@0:   getLeafNameForURL: function Storage_getLeafNameForURL(aURL) {
michael@0:     if (typeof aURL != "string") {
michael@0:       throw new TypeError("Expecting a string");
michael@0:     }
michael@0:     let hash = this._calculateMD5Hash(aURL);
michael@0:     return hash + ".png";
michael@0:   },
michael@0: 
michael@0:   getFilePathForURL: function Storage_getFilePathForURL(aURL) {
michael@0:     return OS.Path.join(this.path, this.getLeafNameForURL(aURL));
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Write the contents of a thumbnail, off the main thread.
michael@0:    *
michael@0:    * @param {string} aURL The url for which to store a thumbnail.
michael@0:    * @param {ArrayBuffer} aData The data to store in the thumbnail, as
michael@0:    * an ArrayBuffer. This array buffer is neutered and cannot be
michael@0:    * reused after the copy.
michael@0:    * @param {boolean} aNoOverwrite If true and the thumbnail's file already
michael@0:    * exists, the file will not be overwritten.
michael@0:    *
michael@0:    * @return {Promise}
michael@0:    */
michael@0:   writeData: function Storage_writeData(aURL, aData, aNoOverwrite) {
michael@0:     let path = this.getFilePathForURL(aURL);
michael@0:     this.ensurePath();
michael@0:     aData = new Uint8Array(aData);
michael@0:     let msg = [
michael@0:       path,
michael@0:       aData,
michael@0:       {
michael@0:         tmpPath: path + ".tmp",
michael@0:         bytes: aData.byteLength,
michael@0:         noOverwrite: aNoOverwrite,
michael@0:         flush: false /*thumbnails do not require the level of guarantee provided by flush*/
michael@0:       }];
michael@0:     return PageThumbsWorker.post("writeAtomic", msg,
michael@0:       msg /*we don't want that message garbage-collected,
michael@0:            as OS.Shared.Type.void_t.in_ptr.toMsg uses C-level
michael@0:            memory tricks to enforce zero-copy*/).
michael@0:       then(null, this._eatNoOverwriteError(aNoOverwrite));
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Copy a thumbnail, off the main thread.
michael@0:    *
michael@0:    * @param {string} aSourceURL The url of the thumbnail to copy.
michael@0:    * @param {string} aTargetURL The url of the target thumbnail.
michael@0:    * @param {boolean} aNoOverwrite If true and the target file already exists,
michael@0:    * the file will not be overwritten.
michael@0:    *
michael@0:    * @return {Promise}
michael@0:    */
michael@0:   copy: function Storage_copy(aSourceURL, aTargetURL, aNoOverwrite) {
michael@0:     this.ensurePath();
michael@0:     let sourceFile = this.getFilePathForURL(aSourceURL);
michael@0:     let targetFile = this.getFilePathForURL(aTargetURL);
michael@0:     let options = { noOverwrite: aNoOverwrite };
michael@0:     return PageThumbsWorker.post("copy", [sourceFile, targetFile, options]).
michael@0:       then(null, this._eatNoOverwriteError(aNoOverwrite));
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Remove a single thumbnail, off the main thread.
michael@0:    *
michael@0:    * @return {Promise}
michael@0:    */
michael@0:   remove: function Storage_remove(aURL) {
michael@0:     return PageThumbsWorker.post("remove", [this.getFilePathForURL(aURL)]);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Remove all thumbnails, off the main thread.
michael@0:    *
michael@0:    * @return {Promise}
michael@0:    */
michael@0:   wipe: Task.async(function* Storage_wipe() {
michael@0:     //
michael@0:     // This operation may be launched during shutdown, so we need to
michael@0:     // take a few precautions to ensure that:
michael@0:     //
michael@0:     // 1. it is not interrupted by shutdown, in which case we
michael@0:     //    could be leaving privacy-sensitive files on disk;
michael@0:     // 2. it is not launched too late during shutdown, in which
michael@0:     //    case this could cause shutdown freezes (see bug 1005487,
michael@0:     //    which will eventually be fixed by bug 965309)
michael@0:     //
michael@0: 
michael@0:     let blocker = () => promise;
michael@0: 
michael@0:     // The following operation will rise an error if we have already
michael@0:     // reached profileBeforeChange, in which case it is too late
michael@0:     // to clear the thumbnail wipe.
michael@0:     AsyncShutdown.profileBeforeChange.addBlocker(
michael@0:       "PageThumbs: removing all thumbnails",
michael@0:       blocker);
michael@0: 
michael@0:     // Start the work only now that `profileBeforeChange` has had
michael@0:     // a chance to throw an error.
michael@0: 
michael@0:     let promise = PageThumbsWorker.post("wipe", [this.path]);
michael@0:     try {
michael@0:       yield promise;
michael@0:     }  finally {
michael@0:        // Generally, we will be done much before profileBeforeChange,
michael@0:        // so let's not hoard blockers.
michael@0:        if ("removeBlocker" in AsyncShutdown.profileBeforeChange) {
michael@0:          // `removeBlocker` was added with bug 985655. In the interest
michael@0:          // of backporting, let's degrade gracefully if `removeBlocker`
michael@0:          // doesn't exist.
michael@0:          AsyncShutdown.profileBeforeChange.removeBlocker(blocker);
michael@0:        }
michael@0:     }
michael@0:   }),
michael@0: 
michael@0:   fileExistsForURL: function Storage_fileExistsForURL(aURL) {
michael@0:     return PageThumbsWorker.post("exists", [this.getFilePathForURL(aURL)]);
michael@0:   },
michael@0: 
michael@0:   isFileRecentForURL: function Storage_isFileRecentForURL(aURL) {
michael@0:     return PageThumbsWorker.post("isFileRecent",
michael@0:                                  [this.getFilePathForURL(aURL),
michael@0:                                   MAX_THUMBNAIL_AGE_SECS]);
michael@0:   },
michael@0: 
michael@0:   _calculateMD5Hash: function Storage_calculateMD5Hash(aValue) {
michael@0:     let hash = gCryptoHash;
michael@0:     let value = gUnicodeConverter.convertToByteArray(aValue);
michael@0: 
michael@0:     hash.init(hash.MD5);
michael@0:     hash.update(value, value.length);
michael@0:     return this._convertToHexString(hash.finish(false));
michael@0:   },
michael@0: 
michael@0:   _convertToHexString: function Storage_convertToHexString(aData) {
michael@0:     let hex = "";
michael@0:     for (let i = 0; i < aData.length; i++)
michael@0:       hex += ("0" + aData.charCodeAt(i).toString(16)).slice(-2);
michael@0:     return hex;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * For functions that take a noOverwrite option, OS.File throws an error if
michael@0:    * the target file exists and noOverwrite is true.  We don't consider that an
michael@0:    * error, and we don't want such errors propagated.
michael@0:    *
michael@0:    * @param {aNoOverwrite} The noOverwrite option used in the OS.File operation.
michael@0:    *
michael@0:    * @return {function} A function that should be passed as the second argument
michael@0:    * to then() (the `onError` argument).
michael@0:    */
michael@0:   _eatNoOverwriteError: function Storage__eatNoOverwriteError(aNoOverwrite) {
michael@0:     return function onError(err) {
michael@0:       if (!aNoOverwrite ||
michael@0:           !(err instanceof OS.File.Error) ||
michael@0:           !err.becauseExists) {
michael@0:         throw err;
michael@0:       }
michael@0:     };
michael@0:   },
michael@0: 
michael@0:   // Deprecated, please do not use
michael@0:   getFileForURL: function Storage_getFileForURL_DEPRECATED(aURL) {
michael@0:     Deprecated.warning("PageThumbs.getFileForURL is deprecated. Please use PageThumbs.getFilePathForURL and OS.File",
michael@0:                        "https://developer.mozilla.org/docs/JavaScript_OS.File");
michael@0:     // Note: Once this method has been removed, we can get rid of the dependency towards FileUtils
michael@0:     return new FileUtils.File(PageThumbsStorage.getFilePathForURL(aURL));
michael@0:   }
michael@0: };
michael@0: 
michael@0: let PageThumbsStorageMigrator = {
michael@0:   get currentVersion() {
michael@0:     try {
michael@0:       return Services.prefs.getIntPref(PREF_STORAGE_VERSION);
michael@0:     } catch (e) {
michael@0:       // The pref doesn't exist, yet. Return version 0.
michael@0:       return 0;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   set currentVersion(aVersion) {
michael@0:     Services.prefs.setIntPref(PREF_STORAGE_VERSION, aVersion);
michael@0:   },
michael@0: 
michael@0:   migrate: function Migrator_migrate() {
michael@0:     let version = this.currentVersion;
michael@0: 
michael@0:     // Storage version 1 never made it to beta.
michael@0:     // At the time of writing only Windows had (ProfD != ProfLD) and we
michael@0:     // needed to move thumbnails from the roaming profile to the locale
michael@0:     // one so that they're not needlessly included in backups and/or
michael@0:     // written via SMB.
michael@0: 
michael@0:     // Storage version 2 also never made it to beta.
michael@0:     // The thumbnail folder structure has been changed and old thumbnails
michael@0:     // were not migrated. Instead, we just renamed the current folder to
michael@0:     // "<name>-old" and will remove it later.
michael@0: 
michael@0:     if (version < 3) {
michael@0:       this.migrateToVersion3();
michael@0:     }
michael@0: 
michael@0:     this.currentVersion = LATEST_STORAGE_VERSION;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Bug 239254 added support for having the disk cache and thumbnail
michael@0:    * directories on a local path (i.e. ~/.cache/) under Linux. We'll first
michael@0:    * try to move the old thumbnails to their new location. If that's not
michael@0:    * possible (because ProfD might be on a different file system than
michael@0:    * ProfLD) we'll just discard them.
michael@0:    *
michael@0:    * @param {string*} local The path to the local profile directory.
michael@0:    * Used for testing. Default argument is good for all non-testing uses.
michael@0:    * @param {string*} roaming The path to the roaming profile directory.
michael@0:    * Used for testing. Default argument is good for all non-testing uses.
michael@0:    */
michael@0:   migrateToVersion3: function Migrator_migrateToVersion3(
michael@0:     local = OS.Constants.Path.localProfileDir,
michael@0:     roaming = OS.Constants.Path.profileDir) {
michael@0:     PageThumbsWorker.post(
michael@0:       "moveOrDeleteAllThumbnails",
michael@0:       [OS.Path.join(roaming, THUMBNAIL_DIRECTORY),
michael@0:        OS.Path.join(local, THUMBNAIL_DIRECTORY)]
michael@0:     );
michael@0:   }
michael@0: };
michael@0: 
michael@0: let PageThumbsExpiration = {
michael@0:   _filters: [],
michael@0: 
michael@0:   init: function Expiration_init() {
michael@0:     gUpdateTimerManager.registerTimer("browser-cleanup-thumbnails", this,
michael@0:                                       EXPIRATION_INTERVAL_SECS);
michael@0:   },
michael@0: 
michael@0:   addFilter: function Expiration_addFilter(aFilter) {
michael@0:     this._filters.push(aFilter);
michael@0:   },
michael@0: 
michael@0:   removeFilter: function Expiration_removeFilter(aFilter) {
michael@0:     let index = this._filters.indexOf(aFilter);
michael@0:     if (index > -1)
michael@0:       this._filters.splice(index, 1);
michael@0:   },
michael@0: 
michael@0:   notify: function Expiration_notify(aTimer) {
michael@0:     let urls = [];
michael@0:     let filtersToWaitFor = this._filters.length;
michael@0: 
michael@0:     let expire = function expire() {
michael@0:       this.expireThumbnails(urls);
michael@0:     }.bind(this);
michael@0: 
michael@0:     // No registered filters.
michael@0:     if (!filtersToWaitFor) {
michael@0:       expire();
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     function filterCallback(aURLs) {
michael@0:       urls = urls.concat(aURLs);
michael@0:       if (--filtersToWaitFor == 0)
michael@0:         expire();
michael@0:     }
michael@0: 
michael@0:     for (let filter of this._filters) {
michael@0:       if (typeof filter == "function")
michael@0:         filter(filterCallback)
michael@0:       else
michael@0:         filter.filterForThumbnailExpiration(filterCallback);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   expireThumbnails: function Expiration_expireThumbnails(aURLsToKeep) {
michael@0:     let path = this.path;
michael@0:     let keep = [PageThumbsStorage.getLeafNameForURL(url) for (url of aURLsToKeep)];
michael@0:     let msg = [
michael@0:       PageThumbsStorage.path,
michael@0:       keep,
michael@0:       EXPIRATION_MIN_CHUNK_SIZE
michael@0:     ];
michael@0: 
michael@0:     return PageThumbsWorker.post(
michael@0:       "expireFilesInDirectory",
michael@0:       msg
michael@0:     );
michael@0:   }
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Interface to a dedicated thread handling I/O
michael@0:  */
michael@0: 
michael@0: let PageThumbsWorker = (function() {
michael@0:   let worker = new PromiseWorker("resource://gre/modules/PageThumbsWorker.js",
michael@0:     OS.Shared.LOG.bind("PageThumbs"));
michael@0:   return {
michael@0:     post: function post(...args) {
michael@0:       let promise = worker.post.apply(worker, args);
michael@0:       return promise.then(
michael@0:         null,
michael@0:         function onError(error) {
michael@0:           // Decode any serialized error
michael@0:           if (error instanceof PromiseWorker.WorkerError) {
michael@0:             throw OS.File.Error.fromMsg(error.data);
michael@0:           } else {
michael@0:             throw error;
michael@0:           }
michael@0:         }
michael@0:       );
michael@0:     }
michael@0:   };
michael@0: })();
michael@0: 
michael@0: let PageThumbsHistoryObserver = {
michael@0:   onDeleteURI: function Thumbnails_onDeleteURI(aURI, aGUID) {
michael@0:     PageThumbsStorage.remove(aURI.spec);
michael@0:   },
michael@0: 
michael@0:   onClearHistory: function Thumbnails_onClearHistory() {
michael@0:     PageThumbsStorage.wipe();
michael@0:   },
michael@0: 
michael@0:   onTitleChanged: function () {},
michael@0:   onBeginUpdateBatch: function () {},
michael@0:   onEndUpdateBatch: function () {},
michael@0:   onVisit: function () {},
michael@0:   onPageChanged: function () {},
michael@0:   onDeleteVisits: function () {},
michael@0: 
michael@0:   QueryInterface: XPCOMUtils.generateQI([Ci.nsINavHistoryObserver])
michael@0: };