/*
* 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.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Vector;
import org.osgi.service.log.LogListener;
import org.osgi.service.log.LogReaderService;
/**
* Implementation of the OSGi {@link LogReaderService} interface. See section 101
* of the OSGi service compendium.
* <p>
* The {@link LogReaderService} maintains a list of {@link org.osgi.service.log.LogEntry}
* objects called the <i>log</i>. The {@link LogReaderService} is a service that bundle
* developers can use to retrieve information contained in this log, and receive
* notifications about {@link org.osgi.service.log.LogEntry} objects when they are created
* through the {@link org.osgi.service.log.LogService}.
*/
final class LogReaderServiceImpl implements LogReaderService
{
/** The log implementation. */
private final Log m_log;
/** The listeners associated with this service. */
private final List m_listeners = new Vector();
/**
* Create a new instance.
* @param log the log implementation
*/
LogReaderServiceImpl(final Log log)
{
this.m_log = log;
}
/**
* This method is used to subscribe to the Log Reader Service in order to receive
* log messages as they occur. Unlike the previously recorded log entries, all
* log messages must be sent to subscribers of the Log Reader Service as they are
* recorded.
* <p>
* A subscriber to the Log Reader Service must implement the {@link LogListener}
* interface.
* <p>
* After a subscription of the Log Reader Service has been started, the subscriber's
* {@link LogListener#logged(LogEntry)} method must be called with a {@link LogEntry}
* object for the message each time a message is logged.
* @param listener the listener object to subscribe
*/
public synchronized void addLogListener(final LogListener listener)
{
m_listeners.add(listener);
m_log.addListener(listener);
}
/**
* This method is used to unsubscribe from the Log Reader Service.
* @param listener the listener object to unsubscribe
*/
public synchronized void removeLogListener(final LogListener listener)
{
m_listeners.remove(listener);
m_log.removeListener(listener);
}
/**
* This method retrieves past log entries as an enumeration with the most recent
* entry first.
* @return an enumeration of the {@link LogEntry} objects that have been stored
*/
public Enumeration getLog()
{
return m_log.getEntries();
}
/**
* Remove all log listeners registered through this service.
*/
synchronized void removeAllLogListeners()
{
Iterator listenerIt = m_listeners.iterator();
while (listenerIt.hasNext())
{
LogListener listener = (LogListener) listenerIt.next();
m_log.removeListener(listener);
}
}
}