PoolСluster auto-restore node

.gitignore

@@ -8,5 +8,6 @@ npm-debug.log
 /test/config.js
 
 *.sublime-*
+.idea
 
 .DS_Store

Readme.md

@@ -406,6 +406,8 @@ poolCluster.end();
 * `canRetry`: If `true`, `PoolCluster` will attempt to reconnect when connection fails. (Default: `true`)
 * `removeNodeErrorCount`: If connection fails, node's `errorCount` increases. 
   When `errorCount` is greater than `removeNodeErrorCount`, remove a node in the `PoolCluster`. (Default: `5`)
+* `restoreNodeTimeout`: If value is greater than `0`, node will not be actually removed.
+  After `restoreNodeTimeout` (ms) node will be automatically restored in `PoolCluster` with `errorCount = 0`. (Default: `0`)
 * `defaultSelector`: The default selector. (Default: `RR`)
   * `RR`: Select one alternately. (Round-Robin)
   * `RANDOM`: Select the node by random function.

lib/PoolCluster.js

@@ -14,6 +14,7 @@ function PoolCluster(config) {
   config = config || {};
   this._canRetry = typeof config.canRetry === 'undefined' ? true : config.canRetry;
   this._removeNodeErrorCount = config.removeNodeErrorCount || 5;
+  this._restoreNodeTimeout = config.restoreNodeTimeout || 0;
   this._defaultSelector = config.defaultSelector || 'RR';
 
   this._closed = false;
@@ -54,6 +55,7 @@ PoolCluster.prototype.add = function(id, config) {
     this._nodes[id] = {
       id: id,
       errorCount: 0,
+      online: true,
       pool: new Pool({config: new PoolConfig(config)})
     };
 
@@ -88,7 +90,9 @@ PoolCluster.prototype.end = function() {
   this._closed = true;
 
   for (var id in this._nodes) {
-    this._nodes[id].pool.end();
+    var node = this._nodes[id];
+    if (node.restoreTimeoutID) clearTimeout(node.restoreTimeoutID);
+    node.pool.end();
   }
 };
 
@@ -124,17 +128,35 @@ PoolCluster.prototype._getNode = function(id) {
 };
 
 PoolCluster.prototype._increaseErrorCount = function(node) {
+  var self = this;
+
   if (++node.errorCount >= this._removeNodeErrorCount) {
     var index = this._serviceableNodeIds.indexOf(node.id);
     if (index !== -1) {
       this._serviceableNodeIds.splice(index, 1);
-      delete this._nodes[node.id];
-
       this._clearFindCaches();
 
-      node.pool.end();
+      if ((this._restoreNodeTimeout > 0) && !node.restoreTimeoutID) {
+        node.online = false;
+        this.emit('offline', node.id);
+
+        node.restoreTimeoutID = setTimeout(function() {
+          delete node.restoreTimeoutID;
+          node.online = true;
+          node.errorCount = 0;
+
+          self._serviceableNodeIds.push(node.id);
+          self._clearFindCaches();
+
+          self.emit('online', node.id);
+        }, this._restoreNodeTimeout);
+      } else {
+        delete this._nodes[node.id];
+
+        node.pool.end();
 
-      this.emit('remove', node.id);
+        this.emit('remove', node.id);
+      }
     }
   }
 };
@@ -182,7 +204,7 @@ PoolNamespace.prototype.getConnection = function(cb) {
   var namespace   = this;
 
   if (clusterNode === null) {
-    var err = new Error('Pool does not exist.')
+    var err = new Error('Pool does not exist.');
     err.code = 'POOL_NOEXIST';
     return cb(err);
   }