/*
 * Copyright 2015 Adam Bien.
 *
 * Licensed 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 com.airhacks.porcupine.execution.control;

import static java.lang.Math.min;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 *
 * @author airhacks.com
 */
public class InstrumentedThreadPoolExecutor extends ThreadPoolExecutor {

    private int minRemainingQueueCapacity;

    public InstrumentedThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
        this.minRemainingQueueCapacity = workQueue.remainingCapacity();
    }

    @Override
    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
    }

    @Override
    protected void beforeExecute(Thread t, Runnable r) {
        super.beforeExecute(t, r);
        int current = super.getQueue().remainingCapacity();
        this.minRemainingQueueCapacity = min(this.minRemainingQueueCapacity, current);
    }

    public int getMinRemainingQueueCapacity() {
        return minRemainingQueueCapacity;
    }
}