Allow user to specify max number of pending connections to a server

Adds a field and two new methods to WebSocketServer: setMaxPendingConnections(int) and getMaxPendingConnections() and uses the value as a parameter when binding the server socket.

src/main/java/org/java_websocket/server/WebSocketServer.java

@@ -26,9 +26,7 @@
 package org.java_websocket.server;
 
 import java.io.IOException;
-import java.net.InetSocketAddress;
-import java.net.ServerSocket;
-import java.net.Socket;
+import java.net.*;
 import java.nio.ByteBuffer;
 import java.nio.channels.CancelledKeyException;
 import java.nio.channels.ClosedByInterruptException;
@@ -108,6 +106,12 @@ public abstract class WebSocketServer extends AbstractWebSocket implements Runna
 
 	private WebSocketServerFactory wsf = new DefaultWebSocketServerFactory();
 
+	/**
+	 * Attribute which allows you to configure the socket "backlog" parameter
+	 * which determines how many client connections can be queued.
+	 */
+	private int maxPendingConnections = -1;
+
 	/**
 	 * Creates a WebSocketServer that will attempt to
 	 * listen on port <var>WebSocketImpl.DEFAULT_PORT</var>.
@@ -308,6 +312,24 @@ public List<Draft> getDraft() {
 		return Collections.unmodifiableList( drafts );
 	}
 
+	/**
+	 * Set the requested maximum number of pending connections on the socket. The exact semantics are implementation
+	 * specific. The value provided should be greater than 0. If it is less than or equal to 0, then
+	 * an implementation specific default will be used. This option will be passed as "backlog" parameter to {@link ServerSocket#bind(SocketAddress, int)}
+	 */
+	public void setMaxPendingConnections(int numberOfConnections) {
+		maxPendingConnections = numberOfConnections;
+	}
+
+	/**
+	 * Returns the currently configured maximum number of pending connections.
+	 *
+	 * @see #setMaxPendingConnections(int)
+	 */
+	public int getMaxPendingConnections() {
+		return maxPendingConnections;
+	}
+
 	// Runnable IMPLEMENTATION /////////////////////////////////////////////////
 	public void run() {
 		if (!doEnsureSingleThread()) {
@@ -505,7 +527,7 @@ private boolean doSetupSelectorAndServerThread() {
 			ServerSocket socket = server.socket();
 			socket.setReceiveBufferSize( WebSocketImpl.RCVBUF );
 			socket.setReuseAddress( isReuseAddr() );
-			socket.bind( address );
+			socket.bind( address, getMaxPendingConnections() );
 			selector = Selector.open();
 			server.register( selector, server.validOps() );
 			startConnectionLostTimer();