/*
* 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.log;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.osgi.service.log.LogEntry;
import org.osgi.service.log.LogListener;
/**
* This class is responsible for asynchronously delivering log messages to
* any {@link LogListener} subscribers. A subscriber can be added using the
* {@link org.osgi.service.log.LogReaderService#addLogListener(LogListener)}
* method.
*/
final class LogListenerThread extends Thread
{
// Whether the thread is stopping or not.
private boolean m_stopping = false;
// The list of entries waiting to be delivered to the log listeners.
private final List m_entriesToDeliver = new ArrayList();
// The list of listeners.
private final List m_listeners = new ArrayList();
/**
* Add an entry to the list of messages to deliver.
* @param entry the log entry to deliver
*/
void addEntry(final LogEntry entry)
{
synchronized (m_entriesToDeliver)
{
m_entriesToDeliver.add(entry);
m_entriesToDeliver.notifyAll();
}
}
/**
* Add a listener to the list of listeners that are subscribed.
* @param listener the listener to add to the list of subscribed listeners
*/
void addListener(final LogListener listener)
{
synchronized (m_listeners)
{
m_listeners.add(listener);
}
}
/**
* Remove a listener from the list of listeners that are subscribed.
* @param listener the listener to remove from the list of subscribed listeners
*/
void removeListener(final LogListener listener)
{
synchronized (m_listeners)
{
m_listeners.remove(listener);
}
}
/**
* Returns the number of listeners that are currently registered.
* @return the number of listeners that are currently registered
*/
int getListenerCount()
{
return m_listeners.size();
}
/**
* Stop the thread. This will happen asynchronously.
*/
void shutdown()
{
synchronized (m_entriesToDeliver)
{
m_stopping = true;
m_entriesToDeliver.notifyAll();
}
}
/**
* The main method of the thread: waits for new messages to be receieved
* and then delivers them to any registered log listeners.
*/
public void run()
{
boolean stop = false;
for (; !stop;)
{
synchronized (m_entriesToDeliver)
{
if (!m_entriesToDeliver.isEmpty())
{
LogEntry entry = (LogEntry) m_entriesToDeliver.remove(0);
synchronized (m_listeners)
{
Iterator listenerIt = m_listeners.iterator();
while (listenerIt.hasNext())
{
try
{
LogListener listener = (LogListener) listenerIt.next();
listener.logged(entry);
}
catch (Throwable t)
{
// catch and discard any exceptions thrown by the listener
}
}
}
}
if (m_entriesToDeliver.isEmpty())
{
try
{
m_entriesToDeliver.wait();
}
catch (InterruptedException e)
{
// do nothing
}
}
}
if (m_stopping)
{
stop = true;
}
}
}
}