Bug 980549 - 'Intermittently unable to unlock lock screen'. r=gwagner.

dom/base/IndexedDBHelper.jsm

@@ -19,9 +19,11 @@ const Ci = Components.interfaces;
 this.EXPORTED_SYMBOLS = ["IndexedDBHelper"];
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
-Cu.import("resource://gre/modules/Services.jsm");
 Cu.importGlobalProperties(["indexedDB"]);
 
+XPCOMUtils.defineLazyModuleGetter(this, 'Services',
+  'resource://gre/modules/Services.jsm');
+
 this.IndexedDBHelper = function IndexedDBHelper() {}
 
 IndexedDBHelper.prototype = {
@@ -88,7 +90,10 @@ IndexedDBHelper.prototype = {
   ensureDB: function ensureDB(aSuccessCb, aFailureCb) {
     if (this._db) {
       if (DEBUG) debug("ensureDB: already have a database, returning early.");
-      aSuccessCb && aSuccessCb();
+      if (aSuccessCb) {
+        Services.tm.currentThread.dispatch(aSuccessCb,
+                                           Ci.nsIThread.DISPATCH_NORMAL);
+      }
       return;
     }
     this.open(aSuccessCb, aFailureCb);

dom/settings/SettingsManager.js

@@ -32,6 +32,13 @@ function SettingsLock(aSettingsManager) {
   this._requests = new Queue();
   this._settingsManager = aSettingsManager;
   this._transaction = null;
+
+  let closeHelper = function() {
+    if (DEBUG) debug("closing lock");
+    this._open = false;
+  }.bind(this);
+
+  Services.tm.currentThread.dispatch(closeHelper, Ci.nsIThread.DISPATCH_NORMAL);
 }
 
 SettingsLock.prototype = {
@@ -65,11 +72,13 @@ SettingsLock.prototype = {
           break;
         case "set":
           let keys = Object.getOwnPropertyNames(info.settings);
+          if (keys.length) {
+            lock._isBusy = true;
+          }
           for (let i = 0; i < keys.length; i++) {
             let key = keys[i];
             let last = i === keys.length - 1;
             if (DEBUG) debug("key: " + key + ", val: " + JSON.stringify(info.settings[key]) + ", type: " + typeof(info.settings[key]));
-            lock._isBusy = true;
             let checkKeyRequest = store.get(key);
 
             checkKeyRequest.onsuccess = function (event) {
@@ -87,15 +96,11 @@ SettingsLock.prototype = {
               let setReq = store.put(obj);
 
               setReq.onsuccess = function() {
-                lock._isBusy = false;
                 cpmm.sendAsyncMessage("Settings:Changed", { key: key, value: userValue });
                 if (last && !request.error) {
                   lock._open = true;
                   Services.DOMRequest.fireSuccess(request, 0);
                   lock._open = false;
-                  if (!lock._requests.isEmpty()) {
-                    lock.process();
-                  }
                 }
               };
 
@@ -104,6 +109,13 @@ SettingsLock.prototype = {
                   Services.DOMRequest.fireError(request, setReq.error.name)
                 }
               };
+
+              if (last) {
+                lock._isBusy = false;
+                if (!lock._requests.isEmpty()) {
+                  lock.process();
+                }
+              }
             };
             checkKeyRequest.onerror = function(event) {
               if (!request.error) {
@@ -111,7 +123,9 @@ SettingsLock.prototype = {
               }
             };
           }
-          break;
+          // Don't break here, instead return. Once the previous requests have
+          // finished this loop will start again.
+          return;
         case "get":
           let getReq = (info.name === "*") ? store.mozGetAll()
                                            : store.mozGetAll(info.name);
@@ -148,22 +162,20 @@ SettingsLock.prototype = {
   },
 
   createTransactionAndProcess: function() {
-    if (this._settingsManager._settingsDB._db) {
-      var lock;
-      while (lock = this._settingsManager._locks.dequeue()) {
-        if (!lock._transaction) {
-          let transactionType = this._settingsManager.hasWritePrivileges ? "readwrite" : "readonly";
-          lock._transaction = lock._settingsManager._settingsDB._db.transaction(SETTINGSSTORE_NAME, transactionType);
-        }
-        if (!lock._isBusy) {
-          lock.process();
-        } else {
-          this._settingsManager._locks.enqueue(lock);
-        }
-      }
-      if (!this._requests.isEmpty() && !this._isBusy) {
-        this.process();
-      }
+    if (DEBUG) debug("database opened, creating transaction");
+
+    let manager = this._settingsManager;
+    let transactionType = manager.hasWritePrivileges ? "readwrite" : "readonly";
+
+    this._transaction =
+      manager._settingsDB._db.transaction(SETTINGSSTORE_NAME, transactionType);
+
+    this.process();
+  },
+
+  maybeProcess: function() {
+    if (this._transaction && !this._isBusy) {
+      this.process();
     }
   },
 
@@ -176,7 +188,7 @@ SettingsLock.prototype = {
     if (this._settingsManager.hasReadPrivileges) {
       let req = Services.DOMRequest.createRequest(this._settingsManager._window);
       this._requests.enqueue({ request: req, intent:"get", name: aName });
-      this.createTransactionAndProcess();
+      this.maybeProcess();
       return req;
     } else {
       if (DEBUG) debug("get not allowed");
@@ -221,7 +233,7 @@ SettingsLock.prototype = {
       if (DEBUG) debug("send: " + JSON.stringify(aSettings));
       let settings = this._serializePreservingBinaries(aSettings);
       this._requests.enqueue({request: req, intent: "set", settings: settings});
-      this.createTransactionAndProcess();
+      this.maybeProcess();
       return req;
     } else {
       if (DEBUG) debug("set not allowed");
@@ -237,7 +249,7 @@ SettingsLock.prototype = {
     if (this._settingsManager.hasWritePrivileges) {
       let req = Services.DOMRequest.createRequest(this._settingsManager._window);
       this._requests.enqueue({ request: req, intent: "clear"});
-      this.createTransactionAndProcess();
+      this.maybeProcess();
       return req;
     } else {
       if (DEBUG) debug("clear not allowed");
@@ -251,7 +263,6 @@ SettingsLock.prototype = {
 };
 
 function SettingsManager() {
-  this._locks = new Queue();
   this._settingsDB = new SettingsDB();
   this._settingsDB.init();
 }
@@ -263,13 +274,6 @@ SettingsManager.prototype = {
     return Cu.cloneInto(obj, this._window);
   },
 
-  nextTick: function nextTick(aCallback, thisObj) {
-    if (thisObj)
-      aCallback = aCallback.bind(thisObj);
-
-    Services.tm.currentThread.dispatch(aCallback, Ci.nsIThread.DISPATCH_NORMAL);
-  },
-
   set onsettingchange(aHandler) {
     this.__DOM_IMPL__.setEventHandler("onsettingchange", aHandler);
   },
@@ -281,12 +285,10 @@ SettingsManager.prototype = {
   createLock: function() {
     if (DEBUG) debug("get lock!");
     var lock = new SettingsLock(this);
-    this._locks.enqueue(lock);
     this._settingsDB.ensureDB(
       function() { lock.createTransactionAndProcess(); },
       function() { dump("Cannot open Settings DB. Trying to open an old version?\n"); }
     );
-    this.nextTick(function() { this._open = false; }, lock);
     return lock;
   },