Memory leak fix in Prototype.

Author: kir

src/prototype/dom/event.js

@@ -593,7 +593,10 @@
     // Remove the entry from the collection;
     var index = entries.indexOf(entry);
     entries.splice(index, 1);
-    
+
+    if (entries.length == 0) {
+      stopObservingEventName(element, eventName);
+    }
     return entry;
   }  
 
@@ -928,6 +931,14 @@
     var i = entries.length;
     while (i--)
       removeEvent(element, eventName, entries[i].responder);
+
+    for (var name in registry) {
+      if (name === 'element') continue;
+      return; // There is another registered event
+    }
+
+    // No other events for the element, destroy the registry:
+    destroyRegistryForElement(element);
   }
 
 

test/unit/event_test.js

@@ -159,7 +159,8 @@ new Test.Unit.Runner({
     var span = $("span"), observer = Prototype.emptyFunction, eventID;
 
     span.observe("test:somethingHappened", observer);
-    
+    span.observe("test:somethingHappened", function() {});
+
     function uidForElement(elem) {
       return elem.uniqueID ? elem.uniqueID : elem._prototypeUID;
     }
@@ -168,17 +169,35 @@ new Test.Unit.Runner({
 
     this.assert(registry, 'registry should exist');
     this.assert(Object.isArray(registry['test:somethingHappened']));
-    this.assertEqual(1, registry['test:somethingHappened'].length);
+    this.assertEqual(2, registry['test:somethingHappened'].length);
 
     span.stopObserving("test:somethingHappened", observer);
 
     registry = Event.cache[uidForElement(span)];
 
     this.assert(registry);
     this.assert(Object.isArray(registry['test:somethingHappened']));
-    this.assertEqual(0, registry['test:somethingHappened'].length);
+    this.assertEqual(1, registry['test:somethingHappened'].length);
   },
 
+  testLastStopObservingClearesCache: function() {
+    var span = $("span"), observer = Prototype.emptyFunction, eventID;
+    delete Event.cache[uidForElement(span)];
+
+    span.observe("test:somethingHappened", observer);
+
+    function uidForElement(elem) {
+      return elem.uniqueID ? elem.uniqueID : elem._prototypeUID;
+    }
+
+    span.stopObserving("test:somethingHappened", observer);
+
+    var registry = Event.cache[uidForElement(span)];
+
+    this.assert(!registry);
+//    console.info(registry)
+  },
+
   testObserveAndStopObservingAreChainable: function() {
     var span = $("span"), observer = Prototype.emptyFunction;