Add a Utils.lock as a sync. version of Wrap.localLock.

services/sync/modules/service.js

@@ -152,6 +152,7 @@ function WeaveSvc() {
 }
 WeaveSvc.prototype = {
 
+  _lock: Utils.lock,
   _localLock: Wrap.localLock,
   _catch: Utils.catch,
   _catchAll: Wrap.catchAll,

services/sync/modules/util.js

@@ -71,6 +71,27 @@ let Utils = {
     };
   },
 
+  /**
+   * Wrap a function to call lock before calling the function then unlock.
+   *
+   * @usage MyObj._lock = Utils.lock;
+   *        MyObj.foo = function() { this._lock(func)(); }
+   */
+  lock: function Utils_lock(func) {
+    let thisArg = this;
+    return function WrappedLock() {
+      if (!thisArg.lock())
+        throw "Could not acquire lock";
+
+      try {
+        return func.call(thisArg);
+      }
+      finally {
+        thisArg.unlock();
+      }
+    };
+  },
+
   /**
    * Wrap functions to notify when it starts and finishes executing or if it got
    * an error. The message is a combination of a provided prefix and local name