Look for next free port if once chosen is busy

This fixes spontaneous java.net.BindException like this one:

Jun 7, 2012 4:41:45 PM org.couchbase.mock.CouchbaseMock start
SEVERE: null
java.net.BindException: Address already in use
    at sun.nio.ch.Net.bind(Native Method)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:137)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:77)
    at sun.net.httpserver.ServerImpl.<init>(ServerImpl.java:88)
    at sun.net.httpserver.HttpServerImpl.<init>(HttpServerImpl.java:50)
    at sun.net.httpserver.DefaultHttpServerProvider.createHttpServer(DefaultHttpServerProvider.java:35)
    at com.sun.net.httpserver.HttpServer.create(HttpServer.java:129)
    at org.couchbase.mock.CouchbaseMock.start(CouchbaseMock.java:374)
    at org.couchbase.mock.CouchbaseMock.main(CouchbaseMock.java:322)

Change-Id: I687a12dd04d1cc4cd9c204bdeebc0159f358aabe
Reviewed-on: http://review.couchbase.org/16981
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>

src/main/java/org/couchbase/mock/CouchbaseMock.java

@@ -24,6 +24,7 @@
 import java.util.logging.Logger;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.net.BindException;
 import java.net.InetSocketAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
@@ -307,11 +308,6 @@ public static void main(String[] args) {
         }
 
         try {
-            if (port == 0) {
-                ServerSocket server = new ServerSocket(0);
-                port = server.getLocalPort();
-                server.close();
-            }
             CouchbaseMock mock = new CouchbaseMock(hostname, port, nodes, vbuckets, bucketsSpec);
             if (harakirimonitor != null) {
                 mock.setupHarakiriMonitor(harakirimonitor, true);
@@ -368,13 +364,27 @@ public void start() {
         }
 
         try {
-            httpServer = HttpServer.create(new InetSocketAddress(port), 10);
+            boolean busy = true;
+            do {
+                if (port == 0) {
+                    ServerSocket server = new ServerSocket(0);
+                    port = server.getLocalPort();
+                    server.close();
+                }
+                try {
+                    httpServer = HttpServer.create(new InetSocketAddress(port), 10);
+                } catch (BindException ex) {
+                    System.err.println("Looks like port " + port + " busy, lets try another one");
+                }
+                busy = false;
+            } while (busy);
             httpServer.createContext("/pools", new PoolsHandler(this)).setAuthenticator(authenticator);
             httpServer.setExecutor(Executors.newCachedThreadPool());
             httpServer.start();
             startupLatch.countDown();
         } catch (IOException ex) {
             Logger.getLogger(CouchbaseMock.class.getName()).log(Level.SEVERE, null, ex);
+            System.exit(-1);
         }
 
     }