Update connection.js to support a "shutdown" command

This change adds a shutdown method that indicates to socketDrained that it should close connections once there are no more notifications to send. The side effect is that the node process will end. I've tested the change both with all successful messages, as well as when a few messages can't be sent. In both cases, the program does not shutdown until all messages that can be successfully sent our sent.

lib/connection.js

@@ -84,6 +84,9 @@ function Connection (options) {
 
 	this.socketId = 0;
 
+	// when true, we end all sockets after the pending notifications reach 0
+	this.shutdownPending = false;
+
 	events.EventEmitter.call(this);
 }
 
@@ -99,7 +102,7 @@ Connection.prototype.checkInitialized = function () {
 };
 
 /**
- * You should never need to call this method, initialisation and connection is handled by {@link Connection#sendNotification}
+ * You should never need to call this method, initialization and connection is handled by {@link Connection#sendNotification}
  * @private
  */
 Connection.prototype.initialize = function () {
@@ -346,7 +349,7 @@ Connection.prototype.socketDrained = function(socket, serviceBuffer) {
 	socket.busy = false;
 	if(this.options.enhanced) {
 		var notification = socket.cachedNotifications[socket.cachedNotifications.length - 1];
-		this.emit('transmitted', notification.notification, notification.recipient);
+		this.emit('transmitted', notification.notification, notification.recipient, socket);
 	}
 	if(serviceBuffer === true && !this.runningOnNextTick) {
 		// There is a possibility that this could add multiple invocations to the 
@@ -362,6 +365,12 @@ Connection.prototype.socketDrained = function(socket, serviceBuffer) {
 		}
 		this.runningOnNextTick = true;
 	}
+	if (this.notificationBuffer.length === 0 && this.shutdownPending) {
+		debug("closing connections");
+		for (var i = this.sockets.length - 1; i >= 0; i--) {
+			this.sockets[i].end();
+		}
+	}
 };
 
 /**
@@ -704,4 +713,11 @@ Connection.prototype.sendNotification = function (notification) {
 	return this.pushNotification(notification, notification.device);
 };
 
+/**
+ * End connetions with APNS once we've finished sending all notifications
+ */
+Connection.prototype.shutdown = function () {
+	this.shutdownPending = true;
+};
+
 module.exports = Connection;