Fix the Pub/Sub implementation to fix unit tests and not have a singl…

…eton.

Problem:
    The original design of the sentinel with Pub/Sub to the switch-master
    message broke the last unit test because it was always connected to the
    previously successful servers.

Analysis:
    In order to not have always stay connected to the old servers the
    subscription to the Pub/Sub message needs to only occur when the
    successful connect occurs.

index.js

@@ -11,7 +11,7 @@ function Sentinel(endpoints) {
 
     this.endpoints = endpoints;
     this.clients = [];
-    this.subscribeToSentinelPubSub();
+    this.pubsub = [];
 }
 
 /**
@@ -21,7 +21,34 @@ function Sentinel(endpoints) {
  * @return {RedisClient}       the RedisClient for the desired endpoint
  */
 Sentinel.prototype.createClient = function(masterName, opts) {
+    // When the client is ready create another client and subscribe to the
+    // switch-master event. Then any time there is a message on the channel it
+    // must be a master change, so reconnect all clients. This avoids combining
+    // the pub/sub client with the normal client and interfering with whatever
+    // the user is trying to do.
+    if (this.pubsub.length == 0) {
+        var self = this;
+        var pubsubOpts = {};
+        pubsubOpts.role = "sentinel";
+        pubsubClient = this.createClientInternal(masterName, pubsubOpts);
+        pubsubClient.subscribe("+switch-master", function(error) {
+            if (error) {
+                console.error("Unable to subscribe to Sentinel PUBSUB",
+                              host, ":", port);
+            }
+        });
+        pubsubClient.on("message", function(channel, message) {
+            console.warn("Received +switch-master message from Redis Sentinel.",
+                         " Reconnecting clients.");
+            self.reconnectAllClients();
+        });
+        pubsubClient.on("error", function(error) {});
+        self.pubsub.push(pubsubClient);
+    }
+    return this.createClientInternal(masterName, opts);
+}
 
+Sentinel.prototype.createClientInternal = function(masterName, opts) {
     if (typeof masterName !== 'string') {
         opts = masterName;
         masterName = 'mymaster';
@@ -115,24 +142,6 @@ Sentinel.prototype.createClient = function(masterName, opts) {
     return client;
 };
 
-/*
- * Listen for '+switch-master' events from Sentinel, and reconnect all clients
- * when received.
- */
-Sentinel.prototype.subscribeToSentinelPubSub = function () {
-    this.endpoints.forEach(function(endpoint) {
-        client = redis.createClient(endpoint.port, endpoint.host);
-        client.subscribe("+switch-master", function(error) {
-            if (error) {
-                console.error("Unable to subscribe to Sentinel PUBSUB", endpoint);
-            }
-        });
-        client.on("message", function(channel, message) {
-            console.warn("Received +switch-master message from Redis Sentinel. Reconnecting clients.");
-            sentinel.reconnectAllClients();
-        });
-    });
-}
 
 /*
  * Ensure that all clients are trying to reconnect.
@@ -310,13 +319,8 @@ function parseSentinelResponse(resArr){
 }
 
 // Shortcut for quickly getting a client from endpoints
-var sentinel = null
 function createClient(endpoints, masterName, options) {
-    if (!sentinel) {
-        // Only create one global sentinel instance to bind to
-        // the Sentinel PUBSUB channel.
-        sentinel = Sentinel(endpoints);
-    }
+    var sentinel = Sentinel(endpoints);
     return sentinel.createClient(masterName, options);
 }