/*
* 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.
*/
package org.apache.tomcat.websocket.server;
import java.io.EOFException;
import java.io.IOException;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import javax.servlet.ServletOutputStream;
import javax.websocket.SendHandler;
import javax.websocket.SendResult;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.res.StringManager;
import org.apache.tomcat.websocket.WsRemoteEndpointImplBase;
/**
* This is the server side {@link javax.websocket.RemoteEndpoint} implementation
* - i.e. what the server uses to send data to the client. Communication is over
* a {@link ServletOutputStream}.
*/
public class WsRemoteEndpointImplServer extends WsRemoteEndpointImplBase {
private static final StringManager sm =
StringManager.getManager(Constants.PACKAGE_NAME);
private static final Log log =
LogFactory.getLog(WsHttpUpgradeHandler.class);
private static final Queue<OnResultRunnable> onResultRunnables =
new ConcurrentLinkedQueue<>();
private final ServletOutputStream sos;
private final WsWriteTimeout wsWriteTimeout;
private final ExecutorService executorService;
private volatile SendHandler handler = null;
private volatile ByteBuffer[] buffers = null;
private volatile long timeoutExpiry = -1;
private volatile boolean close;
public WsRemoteEndpointImplServer(ServletOutputStream sos,
WsServerContainer serverContainer) {
this.sos = sos;
this.wsWriteTimeout = serverContainer.getTimeout();
this.executorService = serverContainer.getExecutorService();
}
@Override
protected final boolean isMasked() {
return false;
}
@Override
protected void doWrite(SendHandler handler, ByteBuffer... buffers) {
this.handler = handler;
this.buffers = buffers;
// This is definitely the same thread that triggered the write so a
// dispatch will be required.
onWritePossible(true);
}
public void onWritePossible(boolean useDispatch) {
boolean complete = true;
try {
// If this is false there will be a call back when it is true
while (sos.isReady()) {
complete = true;
for (ByteBuffer buffer : buffers) {
if (buffer.hasRemaining()) {
complete = false;
sos.write(buffer.array(), buffer.arrayOffset(),
buffer.limit());
buffer.position(buffer.limit());
break;
}
}
if (complete) {
wsWriteTimeout.unregister(this);
clearHandler(null, useDispatch);
if (close) {
close();
}
break;
}
}
} catch (IOException ioe) {
wsWriteTimeout.unregister(this);
clearHandler(ioe, useDispatch);
close();
}
if (!complete) {
// Async write is in progress
long timeout = getSendTimeout();
if (timeout > 0) {
// Register with timeout thread
timeoutExpiry = timeout + System.currentTimeMillis();
wsWriteTimeout.register(this);
}
}
}
@Override
protected void doClose() {
if (handler != null) {
// close() can be triggered by a wide range of scenarios. It is far
// simpler just to always use a dispatch than it is to try and track
// whether or not this method was called by the same thread that
// triggered the write
clearHandler(new EOFException(), true);
}
try {
sos.close();
} catch (IOException e) {
if (log.isInfoEnabled()) {
log.info(sm.getString("wsRemoteEndpointServer.closeFailed"), e);
}
}
wsWriteTimeout.unregister(this);
}
protected long getTimeoutExpiry() {
return timeoutExpiry;
}
/*
* Currently this is only called from the background thread so we could just
* call clearHandler() with useDispatch == false but the method parameter
* was added in case other callers started to use this method to make sure
* that those callers think through what the correct value of useDispatch is
* for them.
*/
protected void onTimeout(boolean useDispatch) {
if (handler != null) {
clearHandler(new SocketTimeoutException(), useDispatch);
}
close();
}
/**
*
* @param t The throwable associated with any error that
* occurred
* @param useDispatch Should {@link SendHandler#onResult(SendResult)} be
* called from a new thread, keeping in mind the
* requirements of
* {@link javax.websocket.RemoteEndpoint.Async}
*/
private void clearHandler(Throwable t, boolean useDispatch) {
// Setting the result marks this (partial) message as
// complete which means the next one may be sent which
// could update the value of the handler. Therefore, keep a
// local copy before signalling the end of the (partial)
// message.
SendHandler sh = handler;
handler = null;
if (sh != null) {
if (useDispatch) {
OnResultRunnable r = onResultRunnables.poll();
if (r == null) {
r = new OnResultRunnable(onResultRunnables);
}
r.init(sh, t);
if (executorService == null || executorService.isShutdown()) {
// Can't use the executor so call the runnable directly.
// This may not be strictly specification compliant in all
// cases but during shutdown only close messages are going
// to be sent so there should not be the issue of nested
// calls leading to stack overflow as described in bug
// 55715. The issues with nested calls was the reason for
// the separate thread requirement in the specification.
r.run();
} else {
executorService.execute(r);
}
} else {
if (t == null) {
sh.onResult(new SendResult());
} else {
sh.onResult(new SendResult(t));
}
}
}
}
private static class OnResultRunnable implements Runnable {
private final Queue<OnResultRunnable> queue;
private volatile SendHandler sh;
private volatile Throwable t;
private OnResultRunnable(Queue<OnResultRunnable> queue) {
this.queue = queue;
}
private void init(SendHandler sh, Throwable t) {
this.sh = sh;
this.t = t;
}
@Override
public void run() {
if (t == null) {
sh.onResult(new SendResult());
} else {
sh.onResult(new SendResult(t));
}
t = null;
sh = null;
// Return the Runnable to the queue when it has been finished with
// Note if this method takes an age to finish there shouldn't be any
// thread safety issues as the fields are cleared above.
queue.add(this);
}
}
}