/*
* Mojito Distributed Hash Table (Mojito DHT)
* Copyright (C) 2006-2007 LimeWire LLC
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.limewire.mojito.handler.response;
import java.io.IOException;
import java.net.SocketAddress;
import java.util.concurrent.ExecutionException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.limewire.mojito.Context;
import org.limewire.mojito.KUID;
import org.limewire.mojito.concurrent.DHTFuture;
import org.limewire.mojito.concurrent.DHTTask;
import org.limewire.mojito.exceptions.DHTException;
import org.limewire.mojito.exceptions.DHTTimeoutException;
import org.limewire.mojito.handler.ResponseHandler;
import org.limewire.mojito.messages.RequestMessage;
import org.limewire.mojito.messages.ResponseMessage;
import org.limewire.mojito.result.Result;
import org.limewire.mojito.settings.ContextSettings;
import org.limewire.mojito.settings.NetworkSettings;
import org.limewire.mojito.util.ContactUtils;
/**
* An abstract base class for ResponseHandlers.
*/
public abstract class AbstractResponseHandler<V extends Result> implements ResponseHandler, DHTTask<V> {
private static final Log LOG = LogFactory.getLog(AbstractResponseHandler.class);
/** The number of errors that have occurred. */
private int errors = 0;
/** The total time that has elapsed since the request was sent. */
private long elapsedTime;
/** The timeout of this handler. */
private long timeout;
/** The maximum number of errors that may occur. */
private int maxErrors;
/** A handle to Context. */
protected final Context context;
private volatile DHTFuture<V> future;
/** The time of the last response we received. */
protected long lastResponseTime = 0L;
public AbstractResponseHandler(Context context) {
this(context, -1L, -1);
}
public AbstractResponseHandler(Context context, long timeout) {
this(context, timeout, -1);
}
public AbstractResponseHandler(Context context, int maxErrors) {
this(context, -1L, maxErrors);
}
public AbstractResponseHandler(Context context, long timeout, int maxErrors) {
this.context = context;
setTimeout(timeout);
setMaxErrors(maxErrors);
}
/**
* Returns the lock Object for the ResponseHandler.
*/
protected Object getLock() {
if (future == null) {
throw new IllegalStateException("Lock is null");
}
return future;
}
/*
* (non-Javadoc)
* @see org.limewire.mojito.concurrent.DHTTask#start(org.limewire.mojito.util.OnewayExchanger)
*/
public void start(DHTFuture<V> future) {
this.future = future;
synchronized (getLock()) {
if (isDone()) {
if (LOG.isInfoEnabled()) {
LOG.info("Cannot start " + this + " because it's already done");
}
return;
}
try {
start();
} catch (DHTException t) {
setException(t);
}
}
}
/**
* Override this method to start the ResponseHandler.
*/
protected abstract void start() throws DHTException;
/*
* (non-Javadoc)
* @see org.limewire.mojito.concurrent.DHTTask#cancel()
*/
public void cancel() {
future.cancel(true);
}
/**
* Sets the timeout of this handler.
*/
public void setTimeout(long timeout) {
if (timeout < 0L) {
this.timeout = NetworkSettings.DEFAULT_TIMEOUT.getValue();
} else {
this.timeout = timeout;
}
}
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#timeout()
*/
public long getTimeout() {
return timeout;
}
/**
* Returns the total time that has elapsed since this
* ResponseHandler is active.
*/
protected long getElapsedTime() {
return elapsedTime;
}
/**
* Returns the time when the last response was received.
*/
protected long getLastResponseTime() {
return lastResponseTime;
}
/**
* Resets the error counter.
*/
protected void resetErrors() {
errors = 0;
}
/**
* Returns the number of errors that have occurred.
*/
protected int getErrors() {
return errors;
}
/**
* Sets the maximum number of errors that may occur before
* we're giving up to re-send a request.
*/
public void setMaxErrors(int maxErrors) {
if (maxErrors < 0) {
this.maxErrors = NetworkSettings.MAX_ERRORS.getValue();
} else {
this.maxErrors = maxErrors;
}
}
/**
* Returns the maximum number of errors that may occur before
* we're giving up to re-send a request.
*/
public int getMaxErrors() {
return maxErrors;
}
/**
* The maximum time we're waiting on a lock. Subclasses
* may overwrite this method to customize the timeout.
*/
public long getWaitOnLockTimeout() {
return ContextSettings.getWaitOnLock(getTimeout());
}
/**
* See handleResponse().
*/
protected abstract void response(ResponseMessage message, long time) throws IOException;
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#handleResponse(com.limegroup.mojito.messages.ResponseMessage, long)
*/
public void handleResponse(ResponseMessage response, long time) throws IOException {
synchronized (getLock()) {
if (isCancelled() || isDone()) {
return;
}
if (LOG.isTraceEnabled()) {
LOG.trace("Received " + response + " from "
+ response.getContact() + " after " + getErrors()
+ " errors and a total time of " + getElapsedTime()
+ "ms");
}
elapsedTime += time;
lastResponseTime = System.currentTimeMillis();
response(response, time);
}
}
/**
* See handleTimeout().
*/
protected abstract void timeout(KUID nodeId, SocketAddress dst, RequestMessage message, long time) throws IOException;
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#handleTimeout(com.limegroup.mojito.KUID, java.net.SocketAddress, com.limegroup.mojito.messages.RequestMessage, long)
*/
public void handleTimeout(KUID nodeId,
SocketAddress dst, RequestMessage request, long time) throws IOException {
synchronized (getLock()) {
if (isCancelled() || isDone()) {
return;
}
if (LOG.isTraceEnabled()) {
LOG.trace(request + " to " + ContactUtils.toString(nodeId, dst)
+ " failed after " + time + "ms");
}
elapsedTime += time;
try {
if (errors < maxErrors) {
resend(nodeId, dst, request);
} else {
timeout(nodeId, dst, request, getElapsedTime());
}
} finally {
errors++;
}
}
}
/**
* Resends the given Message to nodeId/dst.
*/
protected void resend(KUID nodeId, SocketAddress dst, RequestMessage message) throws IOException {
if (LOG.isTraceEnabled()) {
LOG.trace("Re-sending " + message + " to " + ContactUtils.toString(nodeId, dst));
}
context.getMessageDispatcher().send(nodeId, dst, message, this);
}
/**
* See handleError().
*/
protected abstract void error(KUID nodeId, SocketAddress dst, RequestMessage message, IOException e);
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#handleError(com.limegroup.mojito.KUID, java.net.SocketAddress, com.limegroup.mojito.messages.RequestMessage, java.lang.Exception)
*/
public void handleError(KUID nodeId, SocketAddress dst, RequestMessage message, IOException e) {
synchronized (getLock()) {
if (isCancelled() || isDone()) {
return;
}
if (LOG.isErrorEnabled()) {
LOG.error("Sending a " + message + " to "
+ ContactUtils.toString(nodeId, dst) + " failed", e);
}
error(nodeId, dst, message, e);
}
}
/**
* See handleTick().
*/
protected void tick() {
}
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#handleTick()
*/
public void handleTick() {
synchronized (getLock()) {
if (isCancelled() || isDone()) {
return;
}
tick();
}
}
/*
* (non-Javadoc)
* @see com.limegroup.mojito.handler.ResponseHandler#isCancelled()
*/
public boolean isCancelled() {
return future.isCancelled();
}
/**
* Returns whether or not this handler is done which
* means if it has returned a result or threw an
* Exception.
*/
public boolean isDone() {
return future.isDone();
}
/**
* Sets the return value which will be returned by the
* call() method.
*/
protected void setReturnValue(V value) {
future.setValue(value);
}
/**
* Sets the Exception which will be thrown by the
* call() method.
*/
protected void setException(DHTException ex) {
ExecutionException e = new ExecutionException(ex);
e.setStackTrace(ex.getStackTrace());
future.setException(e);
}
/**
* A helper method to throw Timeout Exceptions.
*/
protected void fireTimeoutException(KUID nodeId, SocketAddress address,
RequestMessage request, long time) {
setException(createTimeoutException(nodeId, address, request, time));
}
/**
* A helper method to create Timeout Exceptions.
*/
protected DHTTimeoutException createTimeoutException(KUID nodeId, SocketAddress address,
RequestMessage request, long time) {
return new DHTTimeoutException(nodeId, address, request, time);
}
}