org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorator Maven / Gradle / Ivy
/*
* Copyright 2002-2015 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.springframework.web.socket.handler;
import java.io.IOException;
import java.util.Queue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.WebSocketMessage;
import org.springframework.web.socket.WebSocketSession;
/**
* Wraps a {@link org.springframework.web.socket.WebSocketSession} and guarantees
* only one thread can send messages at a time.
*
* If a send is slow, subsequent attempts to send more messages from a different
* thread will fail to acquire the flush lock and the messages will be buffered
* instead: At that time, the specified buffer-size limit and send-time limit will
* be checked and the session closed if the limits are exceeded.
*
* @author Rossen Stoyanchev
* @since 4.0.3
*/
public class ConcurrentWebSocketSessionDecorator extends WebSocketSessionDecorator {
private static final Log logger = LogFactory.getLog(ConcurrentWebSocketSessionDecorator.class);
private final Queue> buffer = new LinkedBlockingQueue>();
private final AtomicInteger bufferSize = new AtomicInteger();
private final int bufferSizeLimit;
private volatile long sendStartTime;
private final int sendTimeLimit;
private volatile boolean limitExceeded;
private volatile boolean shutdownInProgress;
private final Lock flushLock = new ReentrantLock();
private final Lock closeLock = new ReentrantLock();
/**
* Create a new {@code ConcurrentWebSocketSessionDecorator}.
* @param delegate the {@code WebSocketSession} to delegate to
* @param sendTimeLimit the send-time limit (milliseconds)
* @param bufferSizeLimit the buffer-size limit (number of bytes)
*/
public ConcurrentWebSocketSessionDecorator(WebSocketSession delegate, int sendTimeLimit, int bufferSizeLimit) {
super(delegate);
this.sendTimeLimit = sendTimeLimit;
this.bufferSizeLimit = bufferSizeLimit;
}
public int getBufferSize() {
return this.bufferSize.get();
}
public long getTimeSinceSendStarted() {
long start = this.sendStartTime;
return (start > 0 ? (System.currentTimeMillis() - start) : 0);
}
public void sendMessage(WebSocketMessage message) throws IOException {
if (isDisabled()) {
return;
}
this.buffer.add(message);
this.bufferSize.addAndGet(message.getPayloadLength());
do {
if (!tryFlushMessageBuffer()) {
if (logger.isTraceEnabled()) {
logger.trace("Another send already in progress, session id '" +
getId() + "'" + ", in-progress send time " + getTimeSinceSendStarted() +
" (ms)" + ", buffer size " + this.bufferSize + " bytes");
}
checkSessionLimits();
break;
}
}
while (!this.buffer.isEmpty() && !isDisabled());
}
private boolean isDisabled() {
return (this.limitExceeded || this.shutdownInProgress);
}
private boolean tryFlushMessageBuffer() throws IOException {
if (this.flushLock.tryLock()) {
try {
while (true) {
WebSocketMessage messageToSend = this.buffer.poll();
if (messageToSend == null || isDisabled()) {
break;
}
this.bufferSize.addAndGet(messageToSend.getPayloadLength() * -1);
this.sendStartTime = System.currentTimeMillis();
getDelegate().sendMessage(messageToSend);
this.sendStartTime = 0;
}
}
finally {
this.sendStartTime = 0;
flushLock.unlock();
}
return true;
}
return false;
}
private void checkSessionLimits() throws IOException {
if (!isDisabled() && this.closeLock.tryLock()) {
try {
if (getTimeSinceSendStarted() > this.sendTimeLimit) {
String errorMessage = "Message send time " + getTimeSinceSendStarted() +
" (ms) exceeded the allowed limit " + this.sendTimeLimit;
sessionLimitReached(errorMessage, CloseStatus.SESSION_NOT_RELIABLE);
}
else if (this.bufferSize.get() > this.bufferSizeLimit) {
String errorMessage = "The send buffer size " + this.bufferSize.get() + " bytes for " +
"session '" + getId() + " exceeded the allowed limit " + this.bufferSizeLimit;
sessionLimitReached(errorMessage,
(getTimeSinceSendStarted() >= 10000 ? CloseStatus.SESSION_NOT_RELIABLE : null));
}
}
finally {
this.closeLock.unlock();
}
}
}
private void sessionLimitReached(String reason, CloseStatus status) {
this.limitExceeded = true;
throw new SessionLimitExceededException(reason, status);
}
@Override
public void close(CloseStatus status) throws IOException {
this.shutdownInProgress = true;
super.close(status);
}
@Override
public String toString() {
return getDelegate().toString();
}
}