Better EventEmitter modify-in-emit

Changed ReallyEmit so that it clones the Array of listeners before
processing the emit. Added better tests to make sure that modifying
listeners inside event handlers doesn't cause later listeners to be skipped
or added.

src/node.js

@@ -182,7 +182,7 @@ process.mixin = function() {
 var eventsModule = createInternalModule('events', function (exports) {
   exports.EventEmitter = process.EventEmitter;
 
-  // process.EventEmitter is defined in src/events.cc
+  // process.EventEmitter is defined in src/node_events.cc
   // process.EventEmitter.prototype.emit() is also defined there.
   process.EventEmitter.prototype.addListener = function (type, listener) {
     if (!(listener instanceof Function)) {

src/node_events.cc

@@ -50,7 +50,6 @@ static bool ReallyEmit(Handle<Object> self,
   Local<Object> events = events_v->ToObject();
 
   Local<Value> listeners_v = events->Get(event);
-  Local<Function> listener;
 
   TryCatch try_catch;
 
@@ -66,7 +65,7 @@ static bool ReallyEmit(Handle<Object> self,
     }
 
   } else if (listeners_v->IsArray()) {
-    Local<Array> listeners = Local<Array>::Cast(listeners_v);
+    Local<Array> listeners = Local<Array>::Cast(listeners_v->ToObject()->Clone());
 
     for (uint32_t i = 0; i < listeners->Length(); i++) {
       Local<Value> listener_v = listeners->Get(i);

test/simple/test-event-emitter-modify-in-emit.js

@@ -8,6 +8,7 @@ var e = new events.EventEmitter();
 function callback1() {
     callbacks_called.push("callback1");
     e.addListener("foo", callback2);
+    e.addListener("foo", callback3);
     e.removeListener("foo", callback1);
 }
 
@@ -16,23 +17,39 @@ function callback2() {
     e.removeListener("foo", callback2);
 }
 
+function callback3() {
+    callbacks_called.push("callback3");
+    e.removeListener("foo", callback3);
+}
+
 e.addListener("foo", callback1);
 assert.equal(1, e.listeners("foo").length);
 
 e.emit("foo");
-assert.equal(1, e.listeners("foo").length);
+assert.equal(2, e.listeners("foo").length);
 assert.deepEqual(["callback1"], callbacks_called);
 
 e.emit("foo");
 assert.equal(0, e.listeners("foo").length);
-assert.deepEqual(["callback1", "callback2"], callbacks_called);
+assert.deepEqual(["callback1", "callback2", "callback3"], callbacks_called);
 
 e.emit("foo");
 assert.equal(0, e.listeners("foo").length);
-assert.deepEqual(["callback1", "callback2"], callbacks_called);
+assert.deepEqual(["callback1", "callback2", "callback3"], callbacks_called);
 
 e.addListener("foo", callback1);
 e.addListener("foo", callback2);
 assert.equal(2, e.listeners("foo").length)
 e.removeAllListeners("foo")
-assert.equal(0, e.listeners("foo").length)
+assert.equal(0, e.listeners("foo").length)
+
+// Verify that removing callbacks while in emit allows emits to propagate to 
+// all listeners
+callbacks_called = [ ];
+
+e.addListener("foo", callback2);
+e.addListener("foo", callback3);
+assert.equal(2, e.listeners("foo").length)
+e.emit("foo");
+assert.deepEqual(["callback2", "callback3"], callbacks_called);
+assert.equal(0, e.listeners("foo").length)