org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorator Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* https://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 java.util.function.Consumer;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.lang.Nullable;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.WebSocketMessage;
import org.springframework.web.socket.WebSocketSession;
/**
* Wrap a {@link org.springframework.web.socket.WebSocketSession WebSocketSession}
* to guarantee only one thread can send messages at a time.
*
* If a send is slow, subsequent attempts to send more messages from other threads
* will not be able to acquire the flush lock and messages will be buffered instead.
* At that time, the specified buffer-size limit and send-time limit will be checked
* and the session will be closed if the limits are exceeded.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 4.0.3
*/
public class ConcurrentWebSocketSessionDecorator extends WebSocketSessionDecorator {
private static final Log logger = LogFactory.getLog(ConcurrentWebSocketSessionDecorator.class);
private final int sendTimeLimit;
private final int bufferSizeLimit;
private final OverflowStrategy overflowStrategy;
@Nullable
private Consumer> preSendCallback;
private final Queue> buffer = new LinkedBlockingQueue<>();
private final AtomicInteger bufferSize = new AtomicInteger();
private volatile long sendStartTime;
private volatile boolean limitExceeded;
private volatile boolean closeInProgress;
private final Lock flushLock = new ReentrantLock();
private final Lock closeLock = new ReentrantLock();
/**
* Basic constructor.
* @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) {
this(delegate, sendTimeLimit, bufferSizeLimit, OverflowStrategy.TERMINATE);
}
/**
* Constructor that also specifies the overflow strategy to use.
* @param delegate the {@code WebSocketSession} to delegate to
* @param sendTimeLimit the send-time limit (milliseconds)
* @param bufferSizeLimit the buffer-size limit (number of bytes)
* @param overflowStrategy the overflow strategy to use; by default the
* session is terminated.
* @since 5.1
*/
public ConcurrentWebSocketSessionDecorator(
WebSocketSession delegate, int sendTimeLimit, int bufferSizeLimit, OverflowStrategy overflowStrategy) {
super(delegate);
this.sendTimeLimit = sendTimeLimit;
this.bufferSizeLimit = bufferSizeLimit;
this.overflowStrategy = overflowStrategy;
}
/**
* Return the configured send-time limit (milliseconds).
* @since 4.3.13
*/
public int getSendTimeLimit() {
return this.sendTimeLimit;
}
/**
* Return the configured buffer-size limit (number of bytes).
* @since 4.3.13
*/
public int getBufferSizeLimit() {
return this.bufferSizeLimit;
}
/**
* Return the current buffer size (number of bytes).
*/
public int getBufferSize() {
return this.bufferSize.get();
}
/**
* Return the time (milliseconds) since the current send started,
* or 0 if no send is currently in progress.
*/
public long getTimeSinceSendStarted() {
long start = this.sendStartTime;
return (start > 0 ? (System.currentTimeMillis() - start) : 0);
}
/**
* Set a callback invoked after a message is added to the send buffer.
* @param callback the callback to invoke
* @since 5.3
*/
public void setMessageCallback(Consumer> callback) {
this.preSendCallback = callback;
}
@Override
public void sendMessage(WebSocketMessage message) throws IOException {
if (shouldNotSend()) {
return;
}
this.buffer.add(message);
this.bufferSize.addAndGet(message.getPayloadLength());
if (this.preSendCallback != null) {
this.preSendCallback.accept(message);
}
do {
if (!tryFlushMessageBuffer()) {
if (logger.isTraceEnabled()) {
logger.trace(String.format("Another send already in progress: " +
"session id '%s':, \"in-progress\" send time %d (ms), buffer size %d bytes",
getId(), getTimeSinceSendStarted(), getBufferSize()));
}
checkSessionLimits();
break;
}
}
while (!this.buffer.isEmpty() && !shouldNotSend());
}
private boolean shouldNotSend() {
return (this.limitExceeded || this.closeInProgress);
}
private boolean tryFlushMessageBuffer() throws IOException {
if (this.flushLock.tryLock()) {
try {
while (true) {
WebSocketMessage message = this.buffer.poll();
if (message == null || shouldNotSend()) {
break;
}
this.bufferSize.addAndGet(-message.getPayloadLength());
this.sendStartTime = System.currentTimeMillis();
getDelegate().sendMessage(message);
this.sendStartTime = 0;
}
}
finally {
this.sendStartTime = 0;
this.flushLock.unlock();
}
return true;
}
return false;
}
private void checkSessionLimits() {
if (!shouldNotSend() && this.closeLock.tryLock()) {
try {
if (getTimeSinceSendStarted() > getSendTimeLimit()) {
String format = "Send time %d (ms) for session '%s' exceeded the allowed limit %d";
String reason = String.format(format, getTimeSinceSendStarted(), getId(), getSendTimeLimit());
limitExceeded(reason);
}
else if (getBufferSize() > getBufferSizeLimit()) {
switch (this.overflowStrategy) {
case TERMINATE:
String format = "Buffer size %d bytes for session '%s' exceeds the allowed limit %d";
String reason = String.format(format, getBufferSize(), getId(), getBufferSizeLimit());
limitExceeded(reason);
break;
case DROP:
int i = 0;
while (getBufferSize() > getBufferSizeLimit()) {
WebSocketMessage message = this.buffer.poll();
if (message == null) {
break;
}
this.bufferSize.addAndGet(-message.getPayloadLength());
i++;
}
if (logger.isDebugEnabled()) {
logger.debug("Dropped " + i + " messages, buffer size: " + getBufferSize());
}
break;
default:
// Should never happen..
throw new IllegalStateException("Unexpected OverflowStrategy: " + this.overflowStrategy);
}
}
}
finally {
this.closeLock.unlock();
}
}
}
private void limitExceeded(String reason) {
this.limitExceeded = true;
throw new SessionLimitExceededException(reason, CloseStatus.SESSION_NOT_RELIABLE);
}
@Override
public void close(CloseStatus status) throws IOException {
this.closeLock.lock();
try {
if (this.closeInProgress) {
return;
}
if (!CloseStatus.SESSION_NOT_RELIABLE.equals(status)) {
try {
checkSessionLimits();
}
catch (SessionLimitExceededException ex) {
// Ignore
}
if (this.limitExceeded) {
if (logger.isDebugEnabled()) {
logger.debug("Changing close status " + status + " to SESSION_NOT_RELIABLE.");
}
status = CloseStatus.SESSION_NOT_RELIABLE;
}
}
this.closeInProgress = true;
super.close(status);
}
finally {
this.closeLock.unlock();
}
}
@Override
public String toString() {
return getDelegate().toString();
}
/**
* Enum for options of what to do when the buffer fills up.
* @since 5.1
*/
public enum OverflowStrategy {
/**
* Throw {@link SessionLimitExceededException} that would will result
* in the session being terminated.
*/
TERMINATE,
/**
* Drop the oldest messages from the buffer.
*/
DROP
}
}