/*
* 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.ignite.internal.util.nio;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.ignite.internal.util.typedef.internal.S;
import org.apache.ignite.lang.IgniteRunnable;
/**
* Message tracker.
*/
public class GridNioMessageTracker implements IgniteRunnable {
/** */
private static final long serialVersionUID = 0L;
/** */
private final GridNioSession ses;
/** */
private final int msgQueueLimit;
/** */
private final Lock lock = new ReentrantLock();
/** */
private final AtomicInteger msgCnt = new AtomicInteger();
/** */
private volatile boolean paused;
/**
* @param ses Session.
* @param msgQueueLimit Message queue limit.
*/
public GridNioMessageTracker(GridNioSession ses, int msgQueueLimit) {
this.ses = ses;
this.msgQueueLimit = msgQueueLimit;
}
/** {@inheritDoc} */
@Override public void run() {
// In case of ordered messages this may be called twice for 1 message.
// Example: message arrives, but listener has not been installed yet.
// Message set is created, but message does not get actually processed.
// If this is not called, connection may be paused which causes hang.
// It seems acceptable to have the following logic accounting the aforementioned.
int cnt = 0;
for (;;) {
int cur = msgCnt.get();
if (cur == 0)
break;
cnt = cur - 1;
if (msgCnt.compareAndSet(cur, cnt))
break;
}
assert cnt >= 0 : "Invalid count [cnt=" + cnt + ", this=" + this + ']';
if (cnt < msgQueueLimit && paused && lock.tryLock()) {
try {
// Double check.
if (paused && msgCnt.get() < msgQueueLimit) {
ses.resumeReads();
paused = false;
}
}
finally {
lock.unlock();
}
}
}
/**
*
*/
public void onMessageProcessed() {
run();
}
/**
*/
public void onMessageReceived() {
int cnt = msgCnt.incrementAndGet();
if (cnt >= msgQueueLimit && !paused) {
lock.lock();
try {
// Double check.
if (!paused && msgCnt.get() >= msgQueueLimit) {
ses.pauseReads();
paused = true;
}
}
finally {
lock.unlock();
}
// Need to recheck since message processing threads
// may have failed to acquire lock.
if (paused && msgCnt.get() < msgQueueLimit && lock.tryLock()) {
try {
// Double check only for pause, since count is incremented only
// in this method and only from one (current) thread.
if (paused) {
ses.resumeReads();
paused = false;
}
}
finally {
lock.unlock();
}
}
}
}
/** {@inheritDoc} */
@Override public String toString() {
return S.toString(GridNioMessageTracker.class, this, "hash", System.identityHashCode(this));
}
}