feat(cluster): support update startupNodes in clusterRetryStrategy

Author: luin

README.md

@@ -658,6 +658,14 @@ but a few so that if one is unreachable the client will try the next one, and th
           return delay;
         }
         ```
+    It' possible to modify the `startupNodes` property in order to switch to another set of nodes here:
+
+        ```javascript
+        function (times) {
+          this.startupNodes = [{ port: 6790, host: '127.0.0.1' }];
+          return Math.min(100 + times * 2, 2000);
+        }
+        ```
 
     * `enableOfflineQueue`: Similar to the `enableOfflineQueue` option of `Redis` class.
     * `enableReadyCheck`: When enabled, "ready" event will only be emitted when `CLUSTER INFO` command

lib/cluster/connection_pool.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var util = require('util');
+var utils = require('../utils');
 var EventEmitter = require('events').EventEmitter;
 var _ = require('lodash');
 var Redis = require('../redis');
@@ -77,7 +78,7 @@ ConnectionPool.prototype.findOrCreate = function (node, readOnly) {
     this.emit('+node', redis);
   }
 
-  return this.nodes.all[node.key];
+  return redis;
 };
 
 /**
@@ -89,11 +90,26 @@ ConnectionPool.prototype.findOrCreate = function (node, readOnly) {
  */
 ConnectionPool.prototype.reset = function (nodes) {
   var newNodes = {};
-  for (var i = 0; i < nodes.length; i++) {
-    var node = nodes[i];
-    node.key = node.host + ':' + node.port;
-    newNodes[node.key] = node;
-  }
+  nodes.forEach(function (node) {
+    var options = {};
+    if (typeof node === 'object') {
+      _.defaults(options, node);
+    } else if (typeof node === 'string') {
+      _.defaults(options, utils.parseURL(node));
+    } else if (typeof node === 'number') {
+      options.port = node;
+    } else {
+      throw new Error('Invalid argument ' + node);
+    }
+    if (typeof options.port === 'string') {
+      options.port = parseInt(options.port, 10);
+    }
+    delete options.db;
+
+    options.key = options.host + ':' + options.port;
+    newNodes[options.key] = options;
+  });
+
   var _this = this;
   Object.keys(this.nodes.all).forEach(function (key) {
     if (!newNodes[key]) {

lib/cluster/index.js

@@ -49,28 +49,8 @@ function Cluster(startupNodes, options) {
       '". Expected "all", "master", "slave" or a custom function');
   }
 
-  if (!Array.isArray(startupNodes) || startupNodes.length === 0) {
-    throw new Error('`startupNodes` should contain at least one node.');
-  }
-
   this.connectionPool = new ConnectionPool(this.options.redisOptions);
-  this.startupNodes = startupNodes.map(function (node) {
-    var options = {};
-    if (typeof node === 'object') {
-      _.defaults(options, node);
-    } else if (typeof node === 'string') {
-      _.defaults(options, utils.parseURL(node));
-    } else if (typeof node === 'number') {
-      options.port = node;
-    } else {
-      throw new Error('Invalid argument ' + node);
-    }
-    if (typeof options.port === 'string') {
-      options.port = parseInt(options.port, 10);
-    }
-    delete options.db;
-    return options;
-  });
+  this.startupNodes = startupNodes;
 
   var _this = this;
   this.connectionPool.on('-node', function (redis) {
@@ -151,6 +131,10 @@ Cluster.prototype.connect = function () {
     }
     this.setStatus('connecting');
 
+    if (!Array.isArray(this.startupNodes) || this.startupNodes.length === 0) {
+      throw new Error('`startupNodes` should contain at least one node.');
+    }
+
     this.connectionPool.reset(this.startupNodes);
 
     var closeListener;
@@ -183,7 +167,7 @@ Cluster.prototype.connect = function () {
     this.once('close', function () {
       var retryDelay;
       if (!this.manuallyClosing && typeof this.options.clusterRetryStrategy === 'function') {
-        retryDelay = this.options.clusterRetryStrategy(++this.retryAttempts);
+        retryDelay = this.options.clusterRetryStrategy.call(this, ++this.retryAttempts);
       }
       if (typeof retryDelay === 'number') {
         this.setStatus('reconnecting');

test/unit/cluster.js

@@ -22,20 +22,6 @@ describe('cluster', function () {
     expect(cluster.options).to.have.property('scaleReads', 'master');
   });
 
-  it('should throw when startupNodes is not an array or is empty', function () {
-    expect(function () {
-      new Cluster();
-    }).to.throw(/startupNodes/);
-
-    expect(function () {
-      new Cluster([]);
-    }).to.throw(/startupNodes/);
-
-    expect(function () {
-      new Cluster([{}]);
-    }).to.not.throw(/startupNodes/);
-  });
-
   describe('#executeFailoverCommands', function () {
     it('should execute the commands', function (done) {
       var cluster = {