/*
 * 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.cassandra.concurrent;

import java.lang.management.ManagementFactory;
import java.util.List;

import javax.management.MBeanServer;
import javax.management.ObjectName;

import org.apache.cassandra.metrics.ThreadPoolMetrics;

/**
 * A JMX enabled wrapper for DebuggableScheduledThreadPoolExecutor.
 */
public class JMXEnabledScheduledThreadPoolExecutor extends DebuggableScheduledThreadPoolExecutor implements JMXEnabledScheduledThreadPoolExecutorMBean
{
    private final String mbeanName;
    private final ThreadPoolMetrics metrics;

    public JMXEnabledScheduledThreadPoolExecutor(int corePoolSize, NamedThreadFactory threadFactory, String jmxPath)
    {
        super(corePoolSize, threadFactory);

        metrics = new ThreadPoolMetrics(this, jmxPath, threadFactory.id);

        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
        mbeanName = "org.apache.cassandra." + jmxPath + ":type=" + threadFactory.id;

        try
        {
            mbs.registerMBean(this, new ObjectName(mbeanName));
        }
        catch (Exception e)
        {
            throw new RuntimeException(e);
        }
    }

    private void unregisterMBean()
    {
        try
        {
            ManagementFactory.getPlatformMBeanServer().unregisterMBean(new ObjectName(mbeanName));
        }
        catch (Exception e)
        {
            throw new RuntimeException(e);
        }

        // release metrics
        metrics.release();
    }

    @Override
    public synchronized void shutdown()
    {
        // synchronized, because there is no way to access super.mainLock, which would be
        // the preferred way to make this threadsafe
        if (!isShutdown())
            unregisterMBean();

        super.shutdown();
    }

    @Override
    public synchronized List<Runnable> shutdownNow()
    {
        // synchronized, because there is no way to access super.mainLock, which would be
        // the preferred way to make this threadsafe
        if (!isShutdown())
            unregisterMBean();

        return super.shutdownNow();
    }

    /**
     * Get the number of completed tasks
     */
    public long getCompletedTasks()
    {
        return getCompletedTaskCount();
    }

    /**
     * Get the number of tasks waiting to be executed
     */
    public long getPendingTasks()
    {
        return getTaskCount() - getCompletedTaskCount();
    }

    public int getTotalBlockedTasks()
    {
        return (int) metrics.totalBlocked.count();
    }

    public int getCurrentlyBlockedTasks()
    {
        return (int) metrics.currentBlocked.count();
    }

    public int getCoreThreads()
    {
        return getCorePoolSize();
    }

    public void setCoreThreads(int number)
    {
        setCorePoolSize(number);
    }

    public int getMaximumThreads()
    {
        return getMaximumPoolSize();
    }

    public void setMaximumThreads(int number)
    {
        setMaximumPoolSize(number);
    }
}