content: package org.apache.lucene.store;
  
  /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.net.ServerSocket;
  import java.net.Socket;
  import java.io.OutputStream;
  import java.io.InputStream;
  import java.io.IOException;
  
  /**
   * Simple standalone server that must be running when you
   * use {@link VerifyingLockFactory}.  This server simply
   * verifies at most one process holds the lock at a time.
   * Run without any args to see usage.
   *
   * @see VerifyingLockFactory
   * @see LockStressTest
   */
  
  public class LockVerifyServer {
  
    private static String getTime(long startTime) {
      return "[" + ((System.currentTimeMillis()-startTime)/1000) + "s] ";
    }
  
    public static void main(String[] args) throws IOException {
  
      if (args.length != 1) {
        System.out.println("\nUsage: java org.apache.lucene.store.LockVerifyServer port\n");
        System.exit(1);
      }
  
      final int port = Integer.parseInt(args[0]);
  
      ServerSocket s = new ServerSocket(port);
      s.setReuseAddress(true);
      System.out.println("\nReady on port " + port + "...");
  
      int lockedID = 0;
      long startTime = System.currentTimeMillis();
  
      while(true) {
        Socket cs = s.accept();
        OutputStream out = cs.getOutputStream();
        InputStream in = cs.getInputStream();
  
        int id = in.read();
        int command = in.read();
  
        boolean err = false;
  
        if (command == 1) {
          // Locked
          if (lockedID != 0) {
            err = true;
            System.out.println(getTime(startTime) + " ERROR: id " + id + " got lock, but " + lockedID + " already holds the lock");
          }
          lockedID = id;
        } else if (command == 0) {
          if (lockedID != id) {
            err = true;
            System.out.println(getTime(startTime) + " ERROR: id " + id + " released the lock, but " + lockedID + " is the one holding the lock");
          }
          lockedID = 0;
        } else
          throw new RuntimeException("unrecognized command " + command);
  
        System.out.print(".");
  
        if (err)
          out.write(1);
        else
          out.write(0);
  
        out.close();
        in.close();
        cs.close();
      }
    }
  }
  