extract ClientManager from server.js

Make client manager more robust when piping connections.

lib/Proxy.js

@@ -16,6 +16,8 @@ const Proxy = function(opt) {
     self.waiting = [];
     self.id = opt.id;
 
+    self.activeSockets = 0;
+
     // default max is 10
     self.max_tcp_sockets = opt.max_tcp_sockets || 10;
 
@@ -72,6 +74,8 @@ Proxy.prototype._maybe_destroy = function() {
     const self = this;
 
     clearTimeout(self.conn_timeout);
+
+    // After last socket is gone, we give opportunity to connect again quickly
     self.conn_timeout = setTimeout(function() {
         // sometimes the server is already closed but the event has not fired?
         try {
@@ -81,7 +85,7 @@ Proxy.prototype._maybe_destroy = function() {
         catch (err) {
             self._cleanup();
         }
-    }, 5000);
+    }, 1000);
 }
 
 // new socket connection from client for tunneling requests to client
@@ -89,16 +93,19 @@ Proxy.prototype._handle_socket = function(socket) {
     const self = this;
 
     // no more socket connections allowed
-    if (self.sockets.length >= self.max_tcp_sockets) {
+    if (self.activeSockets >= self.max_tcp_sockets) {
         return socket.end();
     }
 
+    self.activeSockets = self.activeSockets + 1;
+
     self.debug('new connection from: %s:%s', socket.address().address, socket.address().port);
 
     // a single connection is enough to keep client id slot open
     clearTimeout(self.conn_timeout);
 
     socket.once('close', function(had_error) {
+        self.activeSockets = self.activeSockets - 1;
         self.debug('closed socket (error: %s)', had_error);
 
         // what if socket was servicing a request at this time?
@@ -133,10 +140,10 @@ Proxy.prototype._handle_socket = function(socket) {
 
 Proxy.prototype._process_waiting = function() {
     const self = this;
-    const wait_cb = self.waiting.shift();
-    if (wait_cb) {
+    const fn = self.waiting.shift();
+    if (fn) {
         self.debug('handling queued request');
-        self.next_socket(wait_cb);
+        self.nextSocket(fn);
     }
 };
 
@@ -152,48 +159,31 @@ Proxy.prototype._cleanup = function() {
     self.emit('end');
 };
 
-Proxy.prototype.next_socket = function(handler) {
+Proxy.prototype.nextSocket = async function(fn) {
     const self = this;
 
     // socket is a tcp connection back to the user hosting the site
     const sock = self.sockets.shift();
-
     if (!sock) {
-        self.debug('no more client, queue callback');
-        self.waiting.push(handler);
+        self.debug('no more clients, queue callback');
+        self.waiting.push(fn);
         return;
     }
 
     self.debug('processing request');
-    handler(sock)
-    .then(() => {
-        if (!sock.destroyed) {
-            self.debug('retuning socket');
-            self.sockets.push(sock);
-        }
+    await fn(sock);
 
-        // no sockets left to process waiting requests
-        if (self.sockets.length === 0) {
-            return;
-        }
+    if (!sock.destroyed) {
+        self.debug('retuning socket');
+        self.sockets.push(sock);
+    }
 
-        self._process_waiting();
-    })
-    .catch((err) => {
-        log.error(err);
+    // no sockets left to process waiting requests
+    if (self.sockets.length === 0) {
+        return;
+    }
 
-        if (!sock.destroyed) {
-            self.debug('retuning socket');
-            self.sockets.push(sock);
-        }
-
-        // no sockets left to process waiting requests
-        if (self.sockets.length === 0) {
-            return;
-        }
-
-        self._process_waiting();
-    })
+    self._process_waiting();
 };
 
 Proxy.prototype._done = function() {