/*
* 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.felix.eventadmin.impl.tasks;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import org.apache.felix.eventadmin.impl.util.LogWrapper;
/**
*
* A latch that checks handlers for blacklisting on an interval.
*
*/
public class BlacklistLatch {
private final Semaphore internalSemaphore;
private final int count;
private final long timeout;
private final List<HandlerTask> handlerTasks;
/**
* @param count Number of handlers that must call countdown
* @param timeout Timeout in Milliseconds to check for blacklisting handlers
*/
public BlacklistLatch(final int count, final long timeout)
{
this.handlerTasks = new ArrayList<HandlerTask>(count);
this.count = count;
this.timeout = timeout;
internalSemaphore = new Semaphore(count);
internalSemaphore.drainPermits();
}
/**
*
* Count down the number of handlers blocking event completion.
*
*/
public void countDown()
{
internalSemaphore.release();
}
/**
*
* Adds a handler task to the timeout based blackout checking.
*
* @param task
*/
public void addToBlacklistCheck(final HandlerTask task)
{
this.handlerTasks.add(task);
}
/**
*
* Causes current thread to wait until each handler has called countDown.
* Checks on timeout interval to determine if a handler needs blacklisting.
*
*/
public void awaitAndBlacklistCheck()
{
try
{
while(!internalSemaphore.tryAcquire(this.count, this.timeout, TimeUnit.MILLISECONDS))
{
final Iterator<HandlerTask> handlerTaskIt = handlerTasks.iterator();
while(handlerTaskIt.hasNext())
{
HandlerTask currentTask = handlerTaskIt.next();
currentTask.checkForBlacklist();
}
}
}
catch (final InterruptedException e)
{
LogWrapper.getLogger().log(
LogWrapper.LOG_WARNING,
"Event Task Processing Interrupted. Events may not be recieved in proper order.");
}
}
}