Java tutorial
/* * Copyright 2009-2012 the original author or authors. * * Licensed 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. */ package org.cloudfoundry.caldecott.client; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.cloudfoundry.caldecott.TunnelException; import org.springframework.core.task.TaskExecutor; import org.springframework.web.client.HttpStatusCodeException; import org.springframework.web.client.ResourceAccessException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; import java.net.SocketException; import java.net.SocketTimeoutException; import java.util.Observable; /** * The class responsible for handling the actual tunneling communications between a data access client and the * Caldecott server app. * * @author Thomas Risberg */ public class TunnelHandler extends Observable { protected final Log logger = LogFactory.getLog(getClass()); // configuration options private final Socket socket; private final TunnelFactory tunnelFactory; private final TaskExecutor taskExecutor; // variables to keep state for the tunnel setup private Client client; private Tunnel tunnel; // variable to keep handler active // this is volatile since it can we altered by another thread via poke() private volatile boolean shutdown = false; public TunnelHandler(Socket socket, TunnelFactory tunnelFactory, TaskExecutor taskExecutor) { this.socket = socket; this.tunnelFactory = tunnelFactory; this.taskExecutor = taskExecutor; try { this.socket.setSoTimeout(0); } catch (SocketException ignore) { } } public void start() { client = new SocketClient(socket); tunnel = tunnelFactory.createTunnel(); taskExecutor.execute(new Writer()); taskExecutor.execute(new Reader()); if (logger.isDebugEnabled()) { logger.debug("Completed start of: " + this.getClass().getSimpleName() + " with " + countObservers() + " observers"); } } public void poke() { if (client.isIdle()) { shutdown = true; } } public void stop() { try { InputStream is = socket.getInputStream(); if (is != null) { is.close(); } } catch (IOException ignore) { } try { OutputStream os = socket.getOutputStream(); if (os != null) { os.close(); } } catch (IOException ignore) { } if (logger.isDebugEnabled()) { logger.debug("Closing tunnel: " + tunnel.toString()); } tunnel.close(); if (logger.isDebugEnabled()) { logger.debug("Notifying observers: " + countObservers()); } setChanged(); notifyObservers("CLOSED"); } private class Writer implements Runnable { public void run() { if (logger.isDebugEnabled()) { logger.debug("Starting new writer thread: " + this); } try { while (client.isOpen()) { byte[] in = client.read(); if (in.length > 0) { tunnel.write(in); } if (shutdown && client.isIdle()) { if (logger.isDebugEnabled()) { logger.debug("Shutdown requested and idle connection thread will be closed: " + this); } client.forceClose(); stop(); } } } catch (SocketTimeoutException e) { if (logger.isTraceEnabled()) { logger.trace("Retrying tunnel write after receiving " + e.getClass().getName() + ": " + e.getMessage()); } } catch (ResourceAccessException e) { Throwable t = e.getCause(); if (t != null && t instanceof SocketTimeoutException) { if (logger.isTraceEnabled()) { logger.trace("Retrying tunnel write after receiving " + e.getClass().getName() + ": " + e.getMessage()); } } else { logger.error("Caught exception: " + e.getClass().getName() + ": " + e.getMessage()); logger.error("Closing tunnel " + this); stop(); throw e; } } catch (Exception e) { logger.error("Caught exception: " + e.getClass().getName() + ": " + e.getMessage()); logger.error("Closing tunnel " + this); stop(); throw new TunnelException("Fatal exception during tunnel write", e); } if (!shutdown) { stop(); } if (logger.isDebugEnabled()) { logger.debug("Completed writer thread for: " + this); } } } private class Reader implements Runnable { public void run() { if (logger.isDebugEnabled()) { logger.debug("Starting new reader thread: " + this); } boolean retry = false; try { while (client.isOpen()) { try { byte[] out = tunnel.read(retry); retry = false; client.write(out); } catch (HttpStatusCodeException hsce) { if (hsce.getStatusCode().value() == 504 || hsce.getStatusCode().value() == 502) { retry = true; if (logger.isTraceEnabled()) { logger.trace( "Retrying tunnel read after receiving " + hsce.getStatusCode().value()); } } else if (hsce.getStatusCode().value() == 404) { retry = false; if (logger.isDebugEnabled()) { logger.debug("Tunnel error - [" + hsce.getStatusCode().value() + "] " + hsce.getStatusText()); } } else if (hsce.getStatusCode().value() == 410) { retry = false; if (logger.isDebugEnabled()) { logger.debug("Tunnel error - [" + hsce.getStatusCode().value() + "] " + hsce.getStatusText()); } } else { logger.warn("Received HTTP Error: [" + hsce.getStatusCode().value() + "] " + hsce.getStatusText()); throw new TunnelException("Error while reading from tunnel", hsce); } } catch (SocketTimeoutException e) { retry = true; if (logger.isTraceEnabled()) { logger.trace("Retrying tunnel read after receiving " + e.getClass().getName() + ": " + e.getMessage()); } } catch (ResourceAccessException e) { Throwable t = e.getCause(); if (t != null && t instanceof SocketTimeoutException) { retry = true; if (logger.isTraceEnabled()) { logger.trace("Retrying tunnel read after receiving " + e.getClass().getName() + ": " + e.getMessage()); } } else { logger.error("Caught exception: " + e.getClass().getName() + ": " + e.getMessage()); logger.error("Closing tunnel " + this); stop(); throw e; } } catch (RuntimeException e) { logger.error("Caught exception: " + e.getClass().getName() + ": " + e.getMessage()); logger.error("Closing tunnel " + this); stop(); throw e; } } } catch (IOException ioe) { throw new TunnelException("Error while processing streams", ioe); } if (logger.isDebugEnabled()) { logger.debug("Completed reader thread for: " + this); } } } }