Refactor socket add logic

Author: rustyconover

lib/_http_agent.js

@@ -112,11 +112,12 @@ function Agent(options) {
         if (this.sockets[name])
           count += this.sockets[name].length;
 
-        if (count > this.maxSockets) {
-          socket.destroy();
-        } else if (this.keepSocketAlive(socket)) {
+        if (this.keepSocketAlive(socket) &&
+            this.maxFreeSockets > 0 &&
+            count <= this.maxSockets) {
           if (freeLen >= this.maxFreeSockets) {
-            this.freeSockets[name].shift().destroy();
+            const oldest = this.freeSockets[name].shift();
+            oldest.destroy();
           } else {
             freeSockets = freeSockets || [];
             this.freeSockets[name] = freeSockets;