Bug 1389443 - Load handlers.json asynchronously r=florian,Paolo

Asynchronously load handlers.json for nsHandlerService-json.js in
order to avoid blocking IO early on.

MozReview-Commit-ID: F3THSxvXR7I

--HG--
extra : rebase_source : 95d5ccb545cd7d8a09f80586fc2bf2dcf1ea5ab7

browser/components/nsBrowserGlue.js

@@ -483,6 +483,16 @@ BrowserGlue.prototype = {
       case "sync-ui-state:update":
         this._updateFxaBadges();
         break;
+      case "handlersvc-store-initialized":
+        // Initialize PdfJs when running in-process and remote. This only
+        // happens once since PdfJs registers global hooks. If the PdfJs
+        // extension is installed the init method below will be overridden
+        // leaving initialization to the extension.
+        // parent only: configure default prefs, set up pref observers, register
+        // pdf content handler, and initializes parent side message manager
+        // shim for privileged api access.
+        PdfJs.init(true);
+        break;
     }
   },
 
@@ -518,6 +528,7 @@ BrowserGlue.prototype = {
     os.addObserver(this, "flash-plugin-hang");
     os.addObserver(this, "xpi-signature-changed");
     os.addObserver(this, "sync-ui-state:update");
+    os.addObserver(this, "handlersvc-store-initialized");
 
     this._flashHangCount = 0;
     this._firstWindowReady = new Promise(resolve => this._firstWindowLoaded = resolve);
@@ -857,20 +868,12 @@ BrowserGlue.prototype = {
 
   // the first browser window has finished initializing
   _onFirstWindowLoaded: function BG__onFirstWindowLoaded(aWindow) {
-    // Initialize PdfJs when running in-process and remote. This only
-    // happens once since PdfJs registers global hooks. If the PdfJs
-    // extension is installed the init method below will be overridden
-    // leaving initialization to the extension.
-    // parent only: configure default prefs, set up pref observers, register
-    // pdf content handler, and initializes parent side message manager
-    // shim for privileged api access.
-    PdfJs.init(true);
-    // child only: similar to the call above for parent - register content
-    // handler and init message manager child shim for privileged api access.
-    // With older versions of the extension installed, this load will fail
-    // passively.
+    // Set up listeners and, if PdfJs is enabled, register the PDF stream converter.
+    // We delay all of the parent's initialization other than stream converter
+    // registration, because it requires file IO from nsHandlerService-json.js
     Services.ppmm.loadProcessScript("resource://pdf.js/pdfjschildbootstrap.js", true);
     if (PdfJs.enabled) {
+      PdfJs.ensureRegistered();
       Services.ppmm.loadProcessScript("resource://pdf.js/pdfjschildbootstrap-enabled.js", true);
     }
 
@@ -1151,6 +1154,12 @@ BrowserGlue.prototype = {
         Services.tm.idleDispatchToMainThread(Services.startup.trackStartupCrashEnd);
       }, STARTUP_CRASHES_END_DELAY_MS);
     });
+
+    Services.tm.idleDispatchToMainThread(() => {
+      let handlerService = Cc["@mozilla.org/uriloader/handler-service;1"].
+                           getService(Ci.nsIHandlerService);
+      handlerService.asyncInit();
+    });
   },
 
   /**

browser/extensions/pdfjs/content/PdfJs.jsm

@@ -30,6 +30,10 @@ const PREF_PREVIOUS_ACTION = PREF_PREFIX + ".previousHandler.preferredAction";
 const PREF_PREVIOUS_ASK = PREF_PREFIX +
                           ".previousHandler.alwaysAskBeforeHandling";
 const PREF_DISABLED_PLUGIN_TYPES = "plugin.disable_full_page_plugin_for_types";
+const PREF_ENABLED_CACHE_STATE = PREF_PREFIX + ".enabledCache.state";
+const PREF_ENABLED_CACHE_INITIALIZED = PREF_PREFIX +
+                                       ".enabledCache.initialized";
+const PREF_APP_UPDATE_POSTUPDATE = "app.update.postupdate";
 const TOPIC_PDFJS_HANDLER_CHANGED = "pdfjs:handlerChanged";
 const TOPIC_PLUGINS_LIST_UPDATED = "plugins-list-updated";
 const TOPIC_PLUGIN_INFO_UPDATED = "plugin-info-updated";
@@ -190,7 +194,7 @@ var PdfJs = {
   },
 
   updateRegistration: function updateRegistration() {
-    if (this.enabled) {
+    if (this.checkEnabled()) {
       this.ensureRegistered();
     } else {
       this.ensureUnregistered();
@@ -269,26 +273,7 @@ var PdfJs = {
                                         false);
   },
 
-  // nsIObserver
-  observe: function observe(aSubject, aTopic, aData) {
-    if (Services.appinfo.processType !==
-        Services.appinfo.PROCESS_TYPE_DEFAULT) {
-      throw new Error("Only the parent process should be observing PDF " +
-                      "handler changes.");
-    }
-
-    this.updateRegistration();
-    let jsm = "resource://pdf.js/PdfjsChromeUtils.jsm";
-    let PdfjsChromeUtils = Components.utils.import(jsm, {}).PdfjsChromeUtils;
-    PdfjsChromeUtils.notifyChildOfSettingsChange(this.enabled);
-  },
-
-  /**
-   * pdf.js is only enabled if it is both selected as the pdf viewer and if the
-   * global switch enabling it is true.
-   * @return {boolean} Whether or not it's enabled.
-   */
-  get enabled() {
+  _isEnabled: function _isEnabled() {
     var disabled = getBoolPref(PREF_DISABLED, true);
     if (disabled) {
       return false;
@@ -328,6 +313,47 @@ var PdfJs = {
     return !enabledPluginFound;
   },
 
+  checkEnabled: function checkEnabled() {
+    let isEnabled = this._isEnabled();
+    // This will be updated any time we observe a dependency changing, since
+    // updateRegistration internally calls enabled.
+    Services.prefs.setBoolPref(PREF_ENABLED_CACHE_STATE, isEnabled);
+    return isEnabled;
+  },
+
+  // nsIObserver
+  observe: function observe(aSubject, aTopic, aData) {
+    if (Services.appinfo.processType !==
+        Services.appinfo.PROCESS_TYPE_DEFAULT) {
+      throw new Error("Only the parent process should be observing PDF " +
+                      "handler changes.");
+    }
+
+    this.updateRegistration();
+    let jsm = "resource://pdf.js/PdfjsChromeUtils.jsm";
+    let PdfjsChromeUtils = Components.utils.import(jsm, {}).PdfjsChromeUtils;
+    PdfjsChromeUtils.notifyChildOfSettingsChange(this.enabled);
+  },
+
+  /**
+   * pdf.js is only enabled if it is both selected as the pdf viewer and if the
+   * global switch enabling it is true.
+   * @return {boolean} Whether or not it's enabled.
+   */
+  get enabled() {
+    if (!Services.prefs.getBoolPref(PREF_ENABLED_CACHE_INITIALIZED, false)) {
+      // If we just updated, and the cache hasn't been initialized, then we
+      // can't assume a default state, and need to synchronously initialize
+      // PdfJs
+      if (Services.prefs.prefHasUserValue(PREF_APP_UPDATE_POSTUPDATE)) {
+        this.checkEnabled();
+      }
+
+      Services.prefs.setBoolPref(PREF_ENABLED_CACHE_INITIALIZED, true);
+    }
+    return Services.prefs.getBoolPref(PREF_ENABLED_CACHE_STATE, true);
+  },
+
   ensureRegistered: function ensureRegistered() {
     if (this._registered) {
       return;
@@ -350,4 +376,3 @@ var PdfJs = {
     this._registered = false;
   },
 };
-

uriloader/exthandler/ContentHandlerService.cpp

@@ -117,6 +117,11 @@ ContentHandlerService::~ContentHandlerService()
 {
 }
 
+NS_IMETHODIMP ContentHandlerService::AsyncInit()
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 NS_IMETHODIMP ContentHandlerService::Enumerate(nsISimpleEnumerator * *_retval)
 {
   return NS_ERROR_NOT_IMPLEMENTED;

uriloader/exthandler/nsHandlerService-json.js

@@ -44,14 +44,27 @@ HandlerService.prototype = {
         path: OS.Path.join(OS.Constants.Path.profileDir, "handlers.json"),
         dataPostProcessor: this._dataPostProcessor.bind(this),
       });
+    }
+
+    // Always call this even if this.__store was set, since it may have been
+    // set by asyncInit, which might not have completed yet.
+    this._ensureStoreInitialized();
+    return this.__store;
+  },
+
+  __storeInitialized: false,
+  _ensureStoreInitialized() {
+    if (!this.__storeInitialized) {
+      this.__storeInitialized = true;
       this.__store.ensureDataReady();
 
       // We have to inject new default protocol handlers only if we haven't
       // already done this when migrating data from the RDF back-end.
       let alreadyInjected = this._migrateFromRDFIfNeeded();
       this._injectDefaultProtocolHandlersIfNeeded(alreadyInjected);
+
+      Services.obs.notifyObservers(null, "handlersvc-store-initialized");
     }
-    return this.__store;
   },
 
   _dataPostProcessor(data) {
@@ -218,6 +231,7 @@ HandlerService.prototype = {
         await this.__store.finalize();
       }
       this.__store = null;
+      this.__storeInitialized = false;
     })().catch(Cu.reportError);
   },
 
@@ -232,6 +246,22 @@ HandlerService.prototype = {
     });
   },
 
+  // nsIHandlerService
+  asyncInit() {
+    if (!this.__store) {
+      this.__store = new JSONFile({
+        path: OS.Path.join(OS.Constants.Path.profileDir, "handlers.json"),
+        dataPostProcessor: this._dataPostProcessor.bind(this),
+      });
+      this.__store.load().then(() => {
+        // __store can be null if we called _onDBChange in the mean time.
+        if (this.__store) {
+          this._ensureStoreInitialized();
+        }
+      }).catch(Cu.reportError);
+    }
+  },
+
   // nsIHandlerService
   enumerate() {
     let handlers = Cc["@mozilla.org/array;1"]

uriloader/exthandler/nsHandlerService.js

@@ -302,6 +302,9 @@ HandlerService.prototype = {
 
   //**************************************************************************//
   // nsIHandlerService
+  asyncInit: function HS_asyncInit() {
+    // noop
+  },
 
   enumerate: function HS_enumerate() {
     var handlers = Cc["@mozilla.org/array;1"].

uriloader/exthandler/nsIHandlerService.idl

@@ -10,6 +10,12 @@ interface nsISimpleEnumerator;
 [scriptable, uuid(53f0ad17-ec62-46a1-adbc-efccc06babcd)]
 interface nsIHandlerService : nsISupports
 {
+  /**
+   * Asynchronously performs any IO that the nsIHandlerService needs to do
+   * before it can be of use.
+   */
+  void asyncInit();
+
   /**
    * Retrieve a list of all handlers in the datastore.  This list is not
    * guaranteed to be in any particular order, and callers should not assume

uriloader/exthandler/tests/unit/test_handlerService_json.js

@@ -32,6 +32,44 @@ add_task(async function test_store_keeps_unknown_properties() {
               "preserved");
 });
 
+/**
+ * Runs the asyncInit method, ensuring that it successfully inits the store
+ * and calls the handlersvc-store-initialized topic.
+ */
+add_task(async function test_async_init() {
+  await deleteHandlerStore();
+  await copyTestDataToHandlerStore();
+  gHandlerService.asyncInit();
+  await TestUtils.topicObserved("handlersvc-store-initialized");
+  await assertAllHandlerInfosMatchTestData();
+
+  await unloadHandlerStore();
+});
+
+/**
+ * Races the asyncInit method against the sync init (implicit in enumerate),
+ * to ensure that the store will be synchronously initialized without any
+ * ill effects.
+ */
+add_task(async function test_race_async_init() {
+  await deleteHandlerStore();
+  await copyTestDataToHandlerStore();
+  let storeInitialized = false;
+  // Pass a callback to synchronously observe the topic, as a promise would
+  // resolve asynchronously
+  TestUtils.topicObserved("handlersvc-store-initialized", () => {
+    storeInitialized = true;
+    return true;
+  });
+  gHandlerService.asyncInit();
+  do_check_false(storeInitialized);
+  gHandlerService.enumerate();
+  do_check_true(storeInitialized);
+  await assertAllHandlerInfosMatchTestData();
+
+  await unloadHandlerStore();
+});
+
 /**
  * Tests the migration from an existing RDF data source.
  */