Speed up mutex.

renderjs.js

@@ -185,51 +185,22 @@
     if (!(this instanceof Mutex)) {
       return new Mutex();
     }
-    this._latest_defer = null;
+    this._latest_promise = null;
   };
 
   Mutex.prototype = {
     constructor: Mutex,
-
-    lock: function lockMutex() {
-      var previous_defer = this._latest_defer,
-        current_defer = RSVP.defer(),
-        queue = new RSVP.Queue();
-
-      this._latest_defer = current_defer;
-
-      if (previous_defer !== null) {
-        queue.push(function acquireMutex() {
-          return previous_defer.promise;
+    lockAndRun: function lockMutexAndRun(callback) {
+      var previous_promise = this._latest_promise;
+      if (previous_promise === null) {
+        this._latest_promise = RSVP.resolve(callback());
+      } else {
+        this._latest_promise = this._latest_promise
+          .always(function () {
+            return callback();
           });
       }
-
-      // Create a new promise (.then) not cancellable
-      // to allow external cancellation of the callback
-      // without breaking the mutex implementation
-      queue
-        .fail(current_defer.resolve.bind(current_defer));
-
-      return queue
-        .push(function generateMutexUnlock() {
-          return function runAndUnlock(callback) {
-            return ensurePushableQueue(callback)
-              .push(function releaseMutexAfterSuccess(result) {
-                current_defer.resolve(result);
-                return result;
-              }, function releaseMutexAfterError(error) {
-                current_defer.resolve(error);
-                throw error;
-              });
-          };
-        });
-    },
-
-    lockAndRun: function (callback) {
-      return this.lock()
-        .push(function executeLockAndRunCallback(runAndUnlock) {
-          return runAndUnlock(callback);
-        });
+      return this._latest_promise;
     }
   };
 
@@ -671,7 +642,9 @@
         if (!context.hasOwnProperty(mutex_name)) {
           context[mutex_name] = new Mutex();
         }
-        return context[mutex_name].lockAndRun(waitForMethodCallback);
+        return ensurePushableQueue(context[mutex_name].lockAndRun,
+                                   [waitForMethodCallback],
+                                   context[mutex_name]);
       }
       return ensurePushableQueue(callback, argument_list, context);
     };

test/mutex_test.js

@@ -152,14 +152,17 @@
     var mutex = new Mutex(),
       counter = 0;
     stop();
-    expect(4);
+    expect(5);
     function assertCounter(value) {
       equal(counter, value);
       counter += 1;
     }
     function callback1() {
+      return new RSVP.Queue()
+        .push(function () {
           assertCounter(0);
           throw new Error('error in callback1');
+        });
     }
     function callback2() {
       assertCounter(1);
@@ -179,7 +182,7 @@
       })
       .push(undefined, function (error) {
         equal(error.message, 'error in callback1');
-        assertCounter(2);
+        assertCounter(3);
       })
       .always(function () {
         start();
@@ -196,7 +199,10 @@
       counter += 1;
     }
     function callback1() {
+      return new RSVP.Queue()
+        .push(function () {
           ok(false, 'Should not reach that code');
+        });
     }
     function callback2() {
       assertCounter(1);
@@ -208,7 +214,7 @@
         return RSVP.all([
           promise1
             .then(function () {
-              ok(false, 'Should not reach that code');
+              ok(false, 'Should not reach that code 2');
             }, function (error) {
               assertCounter(0);
               equal(error.message, 'Default Message');
@@ -288,76 +294,4 @@
       });
   });
 
-  test('lockAndRun only wait for the callback', function () {
-    var mutex = new Mutex(),
-      counter = 0;
-    stop();
-    expect(4);
-    function assertCounter(value) {
-      equal(counter, value);
-      counter += 1;
-    }
-    function callback1() {
-      assertCounter(0);
-      return 'callback1 result';
-    }
-    function callback2() {
-      assertCounter(1);
-      return 'callback2 result';
-    }
-    return new RSVP.Queue()
-      .push(function () {
-        return RSVP.any([
-          mutex.lockAndRun(callback1)
-            .push(function () {
-              return RSVP.delay(10000);
-            }),
-          mutex.lockAndRun(callback2)
-        ]);
-      })
-      .push(function (result) {
-        equal(result, 'callback2 result');
-        assertCounter(2);
-      })
-      .always(function () {
-        start();
-      });
-  });
-
-  test('lockAndRun only wait for the error callback', function () {
-    var mutex = new Mutex(),
-      counter = 0;
-    stop();
-    expect(4);
-    function assertCounter(value) {
-      equal(counter, value);
-      counter += 1;
-    }
-    function callback1() {
-      assertCounter(0);
-      throw new Error('callback1 error');
-    }
-    function callback2() {
-      assertCounter(1);
-      return 'callback2 result';
-    }
-    return new RSVP.Queue()
-      .push(function () {
-        return RSVP.any([
-          mutex.lockAndRun(callback1)
-            .push(undefined, function () {
-              return RSVP.delay(10000);
-            }),
-          mutex.lockAndRun(callback2)
-        ]);
-      })
-      .push(function (result) {
-        equal(result, 'callback2 result');
-        assertCounter(2);
-      })
-      .always(function () {
-        start();
-      });
-  });
-
 }(renderJS.Mutex, QUnit));
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