The Tor Browser: toolkit/modules/NewTabUtils.jsm@6474c204b198 (annotated)

toolkit/modules/NewTabUtils.jsm@6474c204b198 (annotated)

toolkit/modules/NewTabUtils.jsm

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 this.EXPORTED_SYMBOLS = ["NewTabUtils"];
 const Ci = Components.interfaces;
 const Cc = Components.classes;
 const Cu = Components.utils;
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
   "resource://gre/modules/PlacesUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PageThumbs",
   "resource://gre/modules/PageThumbs.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "BinarySearch",
   "resource://gre/modules/BinarySearch.jsm");
 XPCOMUtils.defineLazyGetter(this, "Timer", () => {
   return Cu.import("resource://gre/modules/Timer.jsm", {});
 });
 XPCOMUtils.defineLazyGetter(this, "gPrincipal", function () {
   let uri = Services.io.newURI("about:newtab", null, null);
   return Services.scriptSecurityManager.getNoAppCodebasePrincipal(uri);
 });
 XPCOMUtils.defineLazyGetter(this, "gCryptoHash", function () {
   return Cc["@mozilla.org/security/hash;1"].createInstance(Ci.nsICryptoHash);
 });
 XPCOMUtils.defineLazyGetter(this, "gUnicodeConverter", function () {
   let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
                     .createInstance(Ci.nsIScriptableUnicodeConverter);
   converter.charset = 'utf8';
   return converter;
 });
 // The preference that tells whether this feature is enabled.
 const PREF_NEWTAB_ENABLED = "browser.newtabpage.enabled";
 // The preference that tells the number of rows of the newtab grid.
 const PREF_NEWTAB_ROWS = "browser.newtabpage.rows";
 // The preference that tells the number of columns of the newtab grid.
 const PREF_NEWTAB_COLUMNS = "browser.newtabpage.columns";
 // The maximum number of results PlacesProvider retrieves from history.
 const HISTORY_RESULTS_LIMIT = 100;
 // The maximum number of links Links.getLinks will return.
 const LINKS_GET_LINKS_LIMIT = 100;
 // The gather telemetry topic.
 const TOPIC_GATHER_TELEMETRY = "gather-telemetry";
 // The amount of time we wait while coalescing updates for hidden pages.
 const SCHEDULE_UPDATE_TIMEOUT_MS = 1000;
 /**
  * Calculate the MD5 hash for a string.
  * @param aValue
  *        The string to convert.
  * @return The base64 representation of the MD5 hash.
  */
 function toHash(aValue) {
   let value = gUnicodeConverter.convertToByteArray(aValue);
   gCryptoHash.init(gCryptoHash.MD5);
   gCryptoHash.update(value, value.length);
   return gCryptoHash.finish(true);
 }
 /**
  * Singleton that provides storage functionality.
  */
 XPCOMUtils.defineLazyGetter(this, "Storage", function() {
   return new LinksStorage();
 });
 function LinksStorage() {
   // Handle migration of data across versions.
   try {
     if (this._storedVersion < this._version) {
       // This is either an upgrade, or version information is missing.
       if (this._storedVersion < 1) {
         // Version 1 moved data from DOM Storage to prefs.  Since migrating from
         // version 0 is no more supported, we just reportError a dataloss later.
         throw new Error("Unsupported newTab storage version");
       }
       // Add further migration steps here.
     }
     else {
       // This is a downgrade.  Since we cannot predict future, upgrades should
       // be backwards compatible.  We will set the version to the old value
       // regardless, so, on next upgrade, the migration steps will run again.
       // For this reason, they should also be able to run multiple times, even
       // on top of an already up-to-date storage.
     }
   } catch (ex) {
     // Something went wrong in the update process, we can't recover from here,
     // so just clear the storage and start from scratch (dataloss!).
     Components.utils.reportError(
       "Unable to migrate the newTab storage to the current version. "+
       "Restarting from scratch.\n" + ex);
     this.clear();
   }
   // Set the version to the current one.
   this._storedVersion = this._version;
 }
 LinksStorage.prototype = {
   get _version() 1,
   get _prefs() Object.freeze({
     pinnedLinks: "browser.newtabpage.pinned",
     blockedLinks: "browser.newtabpage.blocked",
   }),
   get _storedVersion() {
     if (this.__storedVersion === undefined) {
       try {
         this.__storedVersion =
           Services.prefs.getIntPref("browser.newtabpage.storageVersion");
       } catch (ex) {
         // The storage version is unknown, so either:
         // - it's a new profile
         // - it's a profile where versioning information got lost
         // In this case we still run through all of the valid migrations,
         // starting from 1, as if it was a downgrade.  As previously stated the
         // migrations should already support running on an updated store.
         this.__storedVersion = 1;
       }
     }
     return this.__storedVersion;
   },
   set _storedVersion(aValue) {
     Services.prefs.setIntPref("browser.newtabpage.storageVersion", aValue);
     this.__storedVersion = aValue;
     return aValue;
   },
   /**
    * Gets the value for a given key from the storage.
    * @param aKey The storage key (a string).
    * @param aDefault A default value if the key doesn't exist.
    * @return The value for the given key.
    */
   get: function Storage_get(aKey, aDefault) {
     let value;
     try {
       let prefValue = Services.prefs.getComplexValue(this._prefs[aKey],
                                                      Ci.nsISupportsString).data;
       value = JSON.parse(prefValue);
     } catch (e) {}
     return value || aDefault;
   },
   /**
    * Sets the storage value for a given key.
    * @param aKey The storage key (a string).
    * @param aValue The value to set.
    */
   set: function Storage_set(aKey, aValue) {
     // Page titles may contain unicode, thus use complex values.
     let string = Cc["@mozilla.org/supports-string;1"]
                    .createInstance(Ci.nsISupportsString);
     string.data = JSON.stringify(aValue);
     Services.prefs.setComplexValue(this._prefs[aKey], Ci.nsISupportsString,
                                    string);
   },
   /**
    * Removes the storage value for a given key.
    * @param aKey The storage key (a string).
    */
   remove: function Storage_remove(aKey) {
     Services.prefs.clearUserPref(this._prefs[aKey]);
   },
   /**
    * Clears the storage and removes all values.
    */
   clear: function Storage_clear() {
     for (let key in this._prefs) {
       this.remove(key);
     }
   }
 };
 /**
  * Singleton that serves as a registry for all open 'New Tab Page's.
  */
 let AllPages = {
   /**
    * The array containing all active pages.
    */
   _pages: [],
   /**
    * Cached value that tells whether the New Tab Page feature is enabled.
    */
   _enabled: null,
   /**
    * Adds a page to the internal list of pages.
    * @param aPage The page to register.
    */
   register: function AllPages_register(aPage) {
     this._pages.push(aPage);
     this._addObserver();
   },
   /**
    * Removes a page from the internal list of pages.
    * @param aPage The page to unregister.
    */
   unregister: function AllPages_unregister(aPage) {
     let index = this._pages.indexOf(aPage);
     if (index > -1)
       this._pages.splice(index, 1);
   },
   /**
    * Returns whether the 'New Tab Page' is enabled.
    */
   get enabled() {
     if (this._enabled === null)
       this._enabled = Services.prefs.getBoolPref(PREF_NEWTAB_ENABLED);
     return this._enabled;
   },
   /**
    * Enables or disables the 'New Tab Page' feature.
    */
   set enabled(aEnabled) {
     if (this.enabled != aEnabled)
       Services.prefs.setBoolPref(PREF_NEWTAB_ENABLED, !!aEnabled);
   },
   /**
    * Returns the number of registered New Tab Pages (i.e. the number of open
    * about:newtab instances).
    */
   get length() {
     return this._pages.length;
   },
   /**
    * Updates all currently active pages but the given one.
    * @param aExceptPage The page to exclude from updating.
    * @param aHiddenPagesOnly If true, only pages hidden in the preloader are
    *                         updated.
    */
   update: function AllPages_update(aExceptPage, aHiddenPagesOnly=false) {
     this._pages.forEach(function (aPage) {
       if (aExceptPage != aPage)
         aPage.update(aHiddenPagesOnly);
     });
   },
   /**
    * Many individual link changes may happen in a small amount of time over
    * multiple turns of the event loop.  This method coalesces updates by waiting
    * a small amount of time before updating hidden pages.
    */
   scheduleUpdateForHiddenPages: function AllPages_scheduleUpdateForHiddenPages() {
     if (!this._scheduleUpdateTimeout) {
       this._scheduleUpdateTimeout = Timer.setTimeout(() => {
         delete this._scheduleUpdateTimeout;
         this.update(null, true);
       }, SCHEDULE_UPDATE_TIMEOUT_MS);
     }
   },
   get updateScheduledForHiddenPages() {
     return !!this._scheduleUpdateTimeout;
   },
   /**
    * Implements the nsIObserver interface to get notified when the preference
    * value changes or when a new copy of a page thumbnail is available.
    */
   observe: function AllPages_observe(aSubject, aTopic, aData) {
     if (aTopic == "nsPref:changed") {
       // Clear the cached value.
       this._enabled = null;
     }
     // and all notifications get forwarded to each page.
     this._pages.forEach(function (aPage) {
       aPage.observe(aSubject, aTopic, aData);
     }, this);
   },
   /**
    * Adds a preference and new thumbnail observer and turns itself into a
    * no-op after the first invokation.
    */
   _addObserver: function AllPages_addObserver() {
     Services.prefs.addObserver(PREF_NEWTAB_ENABLED, this, true);
     Services.obs.addObserver(this, "page-thumbnail:create", true);
     this._addObserver = function () {};
   },
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference])
 };
 /**
  * Singleton that keeps Grid preferences
  */
 let GridPrefs = {
   /**
    * Cached value that tells the number of rows of newtab grid.
    */
   _gridRows: null,
   get gridRows() {
     if (!this._gridRows) {
       this._gridRows = Math.max(1, Services.prefs.getIntPref(PREF_NEWTAB_ROWS));
     }
     return this._gridRows;
   },
   /**
    * Cached value that tells the number of columns of newtab grid.
    */
   _gridColumns: null,
   get gridColumns() {
     if (!this._gridColumns) {
       this._gridColumns = Math.max(1, Services.prefs.getIntPref(PREF_NEWTAB_COLUMNS));
     }
     return this._gridColumns;
   },
   /**
    * Initializes object. Adds a preference observer
    */
   init: function GridPrefs_init() {
     Services.prefs.addObserver(PREF_NEWTAB_ROWS, this, false);
     Services.prefs.addObserver(PREF_NEWTAB_COLUMNS, this, false);
   },
   /**
    * Implements the nsIObserver interface to get notified when the preference
    * value changes.
    */
   observe: function GridPrefs_observe(aSubject, aTopic, aData) {
     if (aData == PREF_NEWTAB_ROWS) {
       this._gridRows = null;
     } else {
       this._gridColumns = null;
     }
     AllPages.update();
   }
 };
 GridPrefs.init();
 /**
  * Singleton that keeps track of all pinned links and their positions in the
  * grid.
  */
 let PinnedLinks = {
   /**
    * The cached list of pinned links.
    */
   _links: null,
   /**
    * The array of pinned links.
    */
   get links() {
     if (!this._links)
       this._links = Storage.get("pinnedLinks", []);
     return this._links;
   },
   /**
    * Pins a link at the given position.
    * @param aLink The link to pin.
    * @param aIndex The grid index to pin the cell at.
    */
   pin: function PinnedLinks_pin(aLink, aIndex) {
     // Clear the link's old position, if any.
     this.unpin(aLink);
     this.links[aIndex] = aLink;
     this.save();
   },
   /**
    * Unpins a given link.
    * @param aLink The link to unpin.
    */
   unpin: function PinnedLinks_unpin(aLink) {
     let index = this._indexOfLink(aLink);
     if (index == -1)
       return;
     let links = this.links;
     links[index] = null;
     // trim trailing nulls
     let i=links.length-1;
     while (i >= 0 && links[i] == null)
       i--;
     links.splice(i +1);
     this.save();
   },
   /**
    * Saves the current list of pinned links.
    */
   save: function PinnedLinks_save() {
     Storage.set("pinnedLinks", this.links);
   },
   /**
    * Checks whether a given link is pinned.
    * @params aLink The link to check.
    * @return whether The link is pinned.
    */
   isPinned: function PinnedLinks_isPinned(aLink) {
     return this._indexOfLink(aLink) != -1;
   },
   /**
    * Resets the links cache.
    */
   resetCache: function PinnedLinks_resetCache() {
     this._links = null;
   },
   /**
    * Finds the index of a given link in the list of pinned links.
    * @param aLink The link to find an index for.
    * @return The link's index.
    */
   _indexOfLink: function PinnedLinks_indexOfLink(aLink) {
     for (let i = 0; i < this.links.length; i++) {
       let link = this.links[i];
       if (link && link.url == aLink.url)
         return i;
     }
     // The given link is unpinned.
     return -1;
   }
 };
 /**
  * Singleton that keeps track of all blocked links in the grid.
  */
 let BlockedLinks = {
   /**
    * The cached list of blocked links.
    */
   _links: null,
   /**
    * The list of blocked links.
    */
   get links() {
     if (!this._links)
       this._links = Storage.get("blockedLinks", {});
     return this._links;
   },
   /**
    * Blocks a given link.
    * @param aLink The link to block.
    */
   block: function BlockedLinks_block(aLink) {
     this.links[toHash(aLink.url)] = 1;
     this.save();
     // Make sure we unpin blocked links.
     PinnedLinks.unpin(aLink);
   },
   /**
    * Unblocks a given link.
    * @param aLink The link to unblock.
    */
   unblock: function BlockedLinks_unblock(aLink) {
     if (this.isBlocked(aLink)) {
       delete this.links[toHash(aLink.url)];
       this.save();
     }
   },
   /**
    * Saves the current list of blocked links.
    */
   save: function BlockedLinks_save() {
     Storage.set("blockedLinks", this.links);
   },
   /**
    * Returns whether a given link is blocked.
    * @param aLink The link to check.
    */
   isBlocked: function BlockedLinks_isBlocked(aLink) {
     return (toHash(aLink.url) in this.links);
   },
   /**
    * Checks whether the list of blocked links is empty.
    * @return Whether the list is empty.
    */
   isEmpty: function BlockedLinks_isEmpty() {
     return Object.keys(this.links).length == 0;
   },
   /**
    * Resets the links cache.
    */
   resetCache: function BlockedLinks_resetCache() {
     this._links = null;
   }
 };
 /**
  * Singleton that serves as the default link provider for the grid. It queries
  * the history to retrieve the most frequently visited sites.
  */
 let PlacesProvider = {
   /**
    * Set this to change the maximum number of links the provider will provide.
    */
   maxNumLinks: HISTORY_RESULTS_LIMIT,
   /**
    * Must be called before the provider is used.
    */
   init: function PlacesProvider_init() {
     PlacesUtils.history.addObserver(this, true);
   },
   /**
    * Gets the current set of links delivered by this provider.
    * @param aCallback The function that the array of links is passed to.
    */
   getLinks: function PlacesProvider_getLinks(aCallback) {
     let options = PlacesUtils.history.getNewQueryOptions();
     options.maxResults = this.maxNumLinks;
     // Sort by frecency, descending.
     options.sortingMode = Ci.nsINavHistoryQueryOptions.SORT_BY_FRECENCY_DESCENDING
     let links = [];
     let callback = {
       handleResult: function (aResultSet) {
         let row;
         while ((row = aResultSet.getNextRow())) {
           let url = row.getResultByIndex(1);
           if (LinkChecker.checkLoadURI(url)) {
             let title = row.getResultByIndex(2);
             let frecency = row.getResultByIndex(12);
             let lastVisitDate = row.getResultByIndex(5);
             links.push({
               url: url,
               title: title,
               frecency: frecency,
               lastVisitDate: lastVisitDate,
               bgColor: "transparent",
               type: "history",
               imageURI: null,
             });
           }
         }
       },
       handleError: function (aError) {
         // Should we somehow handle this error?
         aCallback([]);
       },
       handleCompletion: function (aReason) {
         // The Places query breaks ties in frecency by place ID descending, but
         // that's different from how Links.compareLinks breaks ties, because
         // compareLinks doesn't have access to place IDs.  It's very important
         // that the initial list of links is sorted in the same order imposed by
         // compareLinks, because Links uses compareLinks to perform binary
         // searches on the list.  So, ensure the list is so ordered.
         let i = 1;
         let outOfOrder = [];
         while (i < links.length) {
           if (Links.compareLinks(links[i - 1], links[i]) > 0)
             outOfOrder.push(links.splice(i, 1)[0]);
           else
             i++;
         }
         for (let link of outOfOrder) {
           i = BinarySearch.insertionIndexOf(links, link,
                                             Links.compareLinks.bind(Links));
           links.splice(i, 0, link);
         }
         aCallback(links);
       }
     };
     // Execute the query.
     let query = PlacesUtils.history.getNewQuery();
     let db = PlacesUtils.history.QueryInterface(Ci.nsPIPlacesDatabase);
     db.asyncExecuteLegacyQueries([query], 1, options, callback);
   },
   /**
    * Registers an object that will be notified when the provider's links change.
    * @param aObserver An object with the following optional properties:
    *        * onLinkChanged: A function that's called when a single link
    *          changes.  It's passed the provider and the link object.  Only the
    *          link's `url` property is guaranteed to be present.  If its `title`
    *          property is present, then its title has changed, and the
    *          property's value is the new title.  If any sort properties are
    *          present, then its position within the provider's list of links may
    *          have changed, and the properties' values are the new sort-related
    *          values.  Note that this link may not necessarily have been present
    *          in the lists returned from any previous calls to getLinks.
    *        * onManyLinksChanged: A function that's called when many links
    *          change at once.  It's passed the provider.  You should call
    *          getLinks to get the provider's new list of links.
    */
   addObserver: function PlacesProvider_addObserver(aObserver) {
     this._observers.push(aObserver);
   },
   _observers: [],
   /**
    * Called by the history service.
    */
   onFrecencyChanged: function PlacesProvider_onFrecencyChanged(aURI, aNewFrecency, aGUID, aHidden, aLastVisitDate) {
     // The implementation of the query in getLinks excludes hidden and
     // unvisited pages, so it's important to exclude them here, too.
     if (!aHidden && aLastVisitDate) {
       this._callObservers("onLinkChanged", {
         url: aURI.spec,
         frecency: aNewFrecency,
         lastVisitDate: aLastVisitDate,
       });
     }
   },
   /**
    * Called by the history service.
    */
   onManyFrecenciesChanged: function PlacesProvider_onManyFrecenciesChanged() {
     this._callObservers("onManyLinksChanged");
   },
   /**
    * Called by the history service.
    */
   onTitleChanged: function PlacesProvider_onTitleChanged(aURI, aNewTitle, aGUID) {
     this._callObservers("onLinkChanged", {
       url: aURI.spec,
       title: aNewTitle
     });
   },
   _callObservers: function PlacesProvider__callObservers(aMethodName, aArg) {
     for (let obs of this._observers) {
       if (obs[aMethodName]) {
         try {
           obs[aMethodName](this, aArg);
         } catch (err) {
           Cu.reportError(err);
         }
       }
     }
   },
   QueryInterface: XPCOMUtils.generateQI([Ci.nsINavHistoryObserver,
                                          Ci.nsISupportsWeakReference]),
 };
 /**
  * Singleton that provides access to all links contained in the grid (including
  * the ones that don't fit on the grid). A link is a plain object that looks
  * like this:
  *
  * {
  *   url: "http://www.mozilla.org/",
  *   title: "Mozilla",
  *   frecency: 1337,
  *   lastVisitDate: 1394678824766431,
  * }
  */
 let Links = {
   /**
    * The maximum number of links returned by getLinks.
    */
   maxNumLinks: LINKS_GET_LINKS_LIMIT,
   /**
    * The link providers.
    */
   _providers: new Set(),
   /**
    * A mapping from each provider to an object { sortedLinks, linkMap }.
    * sortedLinks is the cached, sorted array of links for the provider.  linkMap
    * is a Map from link URLs to link objects.
    */
   _providerLinks: new Map(),
   /**
    * The properties of link objects used to sort them.
    */
   _sortProperties: [
     "frecency",
     "lastVisitDate",
     "url",
   ],
   /**
    * List of callbacks waiting for the cache to be populated.
    */
   _populateCallbacks: [],
   /**
    * Adds a link provider.
    * @param aProvider The link provider.
    */
   addProvider: function Links_addProvider(aProvider) {
     this._providers.add(aProvider);
     aProvider.addObserver(this);
   },
   /**
    * Removes a link provider.
    * @param aProvider The link provider.
    */
   removeProvider: function Links_removeProvider(aProvider) {
     if (!this._providers.delete(aProvider))
       throw new Error("Unknown provider");
     this._providerLinks.delete(aProvider);
   },
   /**
    * Populates the cache with fresh links from the providers.
    * @param aCallback The callback to call when finished (optional).
    * @param aForce When true, populates the cache even when it's already filled.
    */
   populateCache: function Links_populateCache(aCallback, aForce) {
     let callbacks = this._populateCallbacks;
     // Enqueue the current callback.
     callbacks.push(aCallback);
     // There was a callback waiting already, thus the cache has not yet been
     // populated.
     if (callbacks.length > 1)
       return;
     function executeCallbacks() {
       while (callbacks.length) {
         let callback = callbacks.shift();
         if (callback) {
           try {
             callback();
           } catch (e) {
             // We want to proceed even if a callback fails.
           }
         }
       }
     }
     let numProvidersRemaining = this._providers.size;
     for (let provider of this._providers) {
       this._populateProviderCache(provider, () => {
         if (--numProvidersRemaining == 0)
           executeCallbacks();
       }, aForce);
     }
     this._addObserver();
   },
   /**
    * Gets the current set of links contained in the grid.
    * @return The links in the grid.
    */
   getLinks: function Links_getLinks() {
     let pinnedLinks = Array.slice(PinnedLinks.links);
     let links = this._getMergedProviderLinks();
     // Filter blocked and pinned links.
     links = links.filter(function (link) {
       return !BlockedLinks.isBlocked(link) && !PinnedLinks.isPinned(link);
     });
     // Try to fill the gaps between pinned links.
     for (let i = 0; i < pinnedLinks.length && links.length; i++)
       if (!pinnedLinks[i])
         pinnedLinks[i] = links.shift();
     // Append the remaining links if any.
     if (links.length)
       pinnedLinks = pinnedLinks.concat(links);
     return pinnedLinks;
   },
   /**
    * Resets the links cache.
    */
   resetCache: function Links_resetCache() {
     this._providerLinks.clear();
   },
   /**
    * Compares two links.
    * @param aLink1 The first link.
    * @param aLink2 The second link.
    * @return A negative number if aLink1 is ordered before aLink2, zero if
    *         aLink1 and aLink2 have the same ordering, or a positive number if
    *         aLink1 is ordered after aLink2.
    */
   compareLinks: function Links_compareLinks(aLink1, aLink2) {
     for (let prop of this._sortProperties) {
       if (!(prop in aLink1) || !(prop in aLink2))
         throw new Error("Comparable link missing required property: " + prop);
     }
     return aLink2.frecency - aLink1.frecency ||
            aLink2.lastVisitDate - aLink1.lastVisitDate ||
            aLink1.url.localeCompare(aLink2.url);
   },
   /**
    * Calls getLinks on the given provider and populates our cache for it.
    * @param aProvider The provider whose cache will be populated.
    * @param aCallback The callback to call when finished.
    * @param aForce When true, populates the provider's cache even when it's
    *               already filled.
    */
   _populateProviderCache: function Links_populateProviderCache(aProvider, aCallback, aForce) {
     if (this._providerLinks.has(aProvider) && !aForce) {
       aCallback();
     } else {
       aProvider.getLinks(links => {
         // Filter out null and undefined links so we don't have to deal with
         // them in getLinks when merging links from providers.
         links = links.filter((link) => !!link);
         this._providerLinks.set(aProvider, {
           sortedLinks: links,
           linkMap: links.reduce((map, link) => {
             map.set(link.url, link);
             return map;
           }, new Map()),
         });
         aCallback();
       });
     }
   },
   /**
    * Merges the cached lists of links from all providers whose lists are cached.
    * @return The merged list.
    */
   _getMergedProviderLinks: function Links__getMergedProviderLinks() {
     // Build a list containing a copy of each provider's sortedLinks list.
     let linkLists = [];
     for (let links of this._providerLinks.values()) {
       linkLists.push(links.sortedLinks.slice());
     }
     function getNextLink() {
       let minLinks = null;
       for (let links of linkLists) {
         if (links.length &&
             (!minLinks || Links.compareLinks(links[0], minLinks[0]) < 0))
           minLinks = links;
       }
       return minLinks ? minLinks.shift() : null;
     }
     let finalLinks = [];
     for (let nextLink = getNextLink();
          nextLink && finalLinks.length < this.maxNumLinks;
          nextLink = getNextLink()) {
       finalLinks.push(nextLink);
     }
     return finalLinks;
   },
   /**
    * Called by a provider to notify us when a single link changes.
    * @param aProvider The provider whose link changed.
    * @param aLink The link that changed.  If the link is new, it must have all
    *              of the _sortProperties.  Otherwise, it may have as few or as
    *              many as is convenient.
    */
   onLinkChanged: function Links_onLinkChanged(aProvider, aLink) {
     if (!("url" in aLink))
       throw new Error("Changed links must have a url property");
     let links = this._providerLinks.get(aProvider);
     if (!links)
       // This is not an error, it just means that between the time the provider
       // was added and the future time we call getLinks on it, it notified us of
       // a change.
       return;
     let { sortedLinks, linkMap } = links;
     let existingLink = linkMap.get(aLink.url);
     let insertionLink = null;
     let updatePages = false;
     if (existingLink) {
       // Update our copy's position in O(lg n) by first removing it from its
       // list.  It's important to do this before modifying its properties.
       if (this._sortProperties.some(prop => prop in aLink)) {
         let idx = this._indexOf(sortedLinks, existingLink);
         if (idx < 0) {
           throw new Error("Link should be in _sortedLinks if in _linkMap");
         }
         sortedLinks.splice(idx, 1);
         // Update our copy's properties.
         for (let prop of this._sortProperties) {
           if (prop in aLink) {
             existingLink[prop] = aLink[prop];
           }
         }
         // Finally, reinsert our copy below.
         insertionLink = existingLink;
       }
       // Update our copy's title in O(1).
       if ("title" in aLink && aLink.title != existingLink.title) {
         existingLink.title = aLink.title;
         updatePages = true;
       }
     }
     else if (this._sortProperties.every(prop => prop in aLink)) {
       // Before doing the O(lg n) insertion below, do an O(1) check for the
       // common case where the new link is too low-ranked to be in the list.
       if (sortedLinks.length && sortedLinks.length == aProvider.maxNumLinks) {
         let lastLink = sortedLinks[sortedLinks.length - 1];
         if (this.compareLinks(lastLink, aLink) < 0) {
           return;
         }
       }
       // Copy the link object so that changes later made to it by the caller
       // don't affect our copy.
       insertionLink = {};
       for (let prop in aLink) {
         insertionLink[prop] = aLink[prop];
       }
       linkMap.set(aLink.url, insertionLink);
     }
     if (insertionLink) {
       let idx = this._insertionIndexOf(sortedLinks, insertionLink);
       sortedLinks.splice(idx, 0, insertionLink);
       if (sortedLinks.length > aProvider.maxNumLinks) {
         let lastLink = sortedLinks.pop();
         linkMap.delete(lastLink.url);
       }
       updatePages = true;
     }
     if (updatePages)
       AllPages.scheduleUpdateForHiddenPages();
   },
   /**
    * Called by a provider to notify us when many links change.
    */
   onManyLinksChanged: function Links_onManyLinksChanged(aProvider) {
     this._populateProviderCache(aProvider, () => {
       AllPages.scheduleUpdateForHiddenPages();
     }, true);
   },
   _indexOf: function Links__indexOf(aArray, aLink) {
     return this._binsearch(aArray, aLink, "indexOf");
   },
   _insertionIndexOf: function Links__insertionIndexOf(aArray, aLink) {
     return this._binsearch(aArray, aLink, "insertionIndexOf");
   },
   _binsearch: function Links__binsearch(aArray, aLink, aMethod) {
     return BinarySearch[aMethod](aArray, aLink, this.compareLinks.bind(this));
   },
   /**
    * Implements the nsIObserver interface to get notified about browser history
    * sanitization.
    */
   observe: function Links_observe(aSubject, aTopic, aData) {
     // Make sure to update open about:newtab instances. If there are no opened
     // pages we can just wait for the next new tab to populate the cache again.
     if (AllPages.length && AllPages.enabled)
       this.populateCache(function () { AllPages.update() }, true);
     else
       this.resetCache();
   },
   /**
    * Adds a sanitization observer and turns itself into a no-op after the first
    * invokation.
    */
   _addObserver: function Links_addObserver() {
     Services.obs.addObserver(this, "browser:purge-session-history", true);
     this._addObserver = function () {};
   },
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference])
 };
 /**
  * Singleton used to collect telemetry data.
  *
  */
 let Telemetry = {
   /**
    * Initializes object.
    */
   init: function Telemetry_init() {
     Services.obs.addObserver(this, TOPIC_GATHER_TELEMETRY, false);
   },
   /**
    * Collects data.
    */
   _collect: function Telemetry_collect() {
     let probes = [
       { histogram: "NEWTAB_PAGE_ENABLED",
         value: AllPages.enabled },
       { histogram: "NEWTAB_PAGE_PINNED_SITES_COUNT",
         value: PinnedLinks.links.length },
       { histogram: "NEWTAB_PAGE_BLOCKED_SITES_COUNT",
         value: Object.keys(BlockedLinks.links).length }
     ];
     probes.forEach(function Telemetry_collect_forEach(aProbe) {
       Services.telemetry.getHistogramById(aProbe.histogram)
         .add(aProbe.value);
     });
   },
   /**
    * Listens for gather telemetry topic.
    */
   observe: function Telemetry_observe(aSubject, aTopic, aData) {
     this._collect();
   }
 };
 /**
  * Singleton that checks if a given link should be displayed on about:newtab
  * or if we should rather not do it for security reasons. URIs that inherit
  * their caller's principal will be filtered.
  */
 let LinkChecker = {
   _cache: {},
   get flags() {
     return Ci.nsIScriptSecurityManager.DISALLOW_INHERIT_PRINCIPAL |
            Ci.nsIScriptSecurityManager.DONT_REPORT_ERRORS;
   },
   checkLoadURI: function LinkChecker_checkLoadURI(aURI) {
     if (!(aURI in this._cache))
       this._cache[aURI] = this._doCheckLoadURI(aURI);
     return this._cache[aURI];
   },
   _doCheckLoadURI: function Links_doCheckLoadURI(aURI) {
     try {
       Services.scriptSecurityManager.
         checkLoadURIStrWithPrincipal(gPrincipal, aURI, this.flags);
       return true;
     } catch (e) {
       // We got a weird URI or one that would inherit the caller's principal.
       return false;
     }
   }
 };
 let ExpirationFilter = {
   init: function ExpirationFilter_init() {
     PageThumbs.addExpirationFilter(this);
   },
   filterForThumbnailExpiration:
   function ExpirationFilter_filterForThumbnailExpiration(aCallback) {
     if (!AllPages.enabled) {
       aCallback([]);
       return;
     }
     Links.populateCache(function () {
       let urls = [];
       // Add all URLs to the list that we want to keep thumbnails for.
       for (let link of Links.getLinks().slice(0, 25)) {
         if (link && link.url)
           urls.push(link.url);
       }
       aCallback(urls);
     });
   }
 };
 /**
  * Singleton that provides the public API of this JSM.
  */
 this.NewTabUtils = {
   _initialized: false,
   init: function NewTabUtils_init() {
     if (this.initWithoutProviders()) {
       PlacesProvider.init();
       Links.addProvider(PlacesProvider);
     }
   },
   initWithoutProviders: function NewTabUtils_initWithoutProviders() {
     if (!this._initialized) {
       this._initialized = true;
       ExpirationFilter.init();
       Telemetry.init();
       return true;
     }
     return false;
   },
   /**
    * Restores all sites that have been removed from the grid.
    */
   restore: function NewTabUtils_restore() {
     Storage.clear();
     Links.resetCache();
     PinnedLinks.resetCache();
     BlockedLinks.resetCache();
     Links.populateCache(function () {
       AllPages.update();
     }, true);
   },
   /**
    * Undoes all sites that have been removed from the grid and keep the pinned
    * tabs.
    * @param aCallback the callback method.
    */
   undoAll: function NewTabUtils_undoAll(aCallback) {
     Storage.remove("blockedLinks");
     Links.resetCache();
     BlockedLinks.resetCache();
     Links.populateCache(aCallback, true);
   },
   links: Links,
   allPages: AllPages,
   linkChecker: LinkChecker,
   pinnedLinks: PinnedLinks,
   blockedLinks: BlockedLinks,
   gridPrefs: GridPrefs
 };

The Tor Browser / annotate

toolkit/modules/NewTabUtils.jsm@6474c204b198 (annotated)

toolkit/modules/NewTabUtils.jsm