Remove Stale connections that have not been used for idletimeout period of time. mysqljs#962

Author: aankur

lib/Pool.js

@@ -17,6 +17,39 @@ function Pool(options) {
   this._freeConnections      = [];
   this._connectionQueue      = [];
   this._closed               = false;
+  this._recycleTimer         = null;
+}
+
+function recycleStaleConnections()  {
+  var now = Date.now();
+  var min = null;
+  for(var i=0 ;i<this._freeConnections.length; i++ )  {
+    var lastused = this._freeConnections[i]._usedTimestamp;
+
+    if(lastused != undefined) {
+      if((now - lastused) >= this.config.idleTimeout) {
+        this._freeConnections[i].destroy();
+        i--;
+      } else {
+        if(min == null) {
+          min = now - lastused
+        } else {
+          if((now - lastused) < min)  {
+            min = now - lastused;
+          }
+        }
+      }
+    }
+  }
+  if(min != null) {
+    if(min > 0) {
+      clearInterval(this._recycleTimer);
+      this._recycleTimer   = setInterval(recycleStaleConnections.bind(this),this.config.idleTimeout);
+    }
+  } else {
+    clearInterval(this._recycleTimer);
+    this._recycleTimer = null;
+  }
 }
 
 Pool.prototype.getConnection = function (cb) {
@@ -138,6 +171,11 @@ Pool.prototype.releaseConnection = function releaseConnection(connection) {
       throw new Error('Connection already released');
     } else {
       // add connection to end of free queue
+      if(this.config.idleTimeout > 0 && this._recycleTimer == null) {
+        this._recycleTimer = setInterval(recycleStaleConnections.bind(this),this.config.idleTimeout);
+      }
+
+      connection._usedTimestamp = Date.now();
       this._freeConnections.push(connection);
       this.emit('release', connection);
     }
@@ -160,6 +198,10 @@ Pool.prototype.releaseConnection = function releaseConnection(connection) {
 
 Pool.prototype.end = function (cb) {
   this._closed = true;
+  if(this._recycleTimer) {
+      clearInterval(this._recycleTimer);
+      this._recycleTimer = null;
+  }
 
   if (typeof cb !== 'function') {
     cb = function (err) {

lib/PoolConfig.js

@@ -20,6 +20,7 @@ function PoolConfig(options) {
   this.queueLimit         = (options.queueLimit === undefined)
     ? 0
     : Number(options.queueLimit);
+  this.idleTimeout = (options.idleTimeout === undefined)? 0 : Number(options.idleTimeout);
 }
 
 PoolConfig.prototype.newConnectionConfig = function newConnectionConfig() {