org.apache.awf.io.callback.JMXDebuggableCallbackManager.java Source code

Introduction

Here is the source code for org.apache.awf.io.callback.JMXDebuggableCallbackManager.java

Source

/*
 *  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.awf.io.callback;

import java.util.AbstractCollection;
import java.util.List;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.awf.util.MXBeanUtil;
import org.apache.awf.web.AsyncCallback;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Lists;

public class JMXDebuggableCallbackManager implements CallbackManager, CallbackManagerMXBean {

    private final Logger logger = LoggerFactory.getLogger(JMXDebuggableCallbackManager.class);

    private final AbstractCollection<AsyncCallback> callbacks = new ConcurrentLinkedQueue<AsyncCallback>();

    private static final AtomicInteger sequence = new AtomicInteger();

    public JMXDebuggableCallbackManager() { // instance initialization block
        MXBeanUtil.registerMXBean(this, "CallbackManager",
                this.getClass().getSimpleName() + "-" + sequence.incrementAndGet());
    }

    @Override
    public int getNumberOfCallbacks() {
        return callbacks.size();
    }

    @Override
    public void addCallback(AsyncCallback callback) {
        callbacks.add(callback);
        logger.debug("Callback added");
    }

    @Override
    public boolean execute() {
        // makes a defensive copy to avoid (1) CME (new callbacks are added this iteration) and (2) IO starvation.
        List<AsyncCallback> defensive = Lists.newLinkedList(callbacks);
        callbacks.clear();
        for (AsyncCallback callback : defensive) {
            callback.onCallback();
            logger.debug("Callback executed");
        }
        return !callbacks.isEmpty();
    }

}