xenadmin/XenModel/Actions/ProduceConsumerQueue.cs

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 *     following disclaimer. 
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
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using System;
using System.Threading;
using System.Collections.Generic;

public class ProduceConsumerQueue
{
    readonly object _locker = new object();
    Thread[] _workers;
    Queue<Action> _itemQ = new Queue<Action>();

    public ProduceConsumerQueue(int workerCount)
    {
        _workers = new Thread[workerCount];
        for (int i = 0; i < workerCount; i++)
            (_workers[i] = new Thread(Consume) { IsBackground = true }).Start();
    }

    public void StopWorkers(bool waitForWorkers)
    {
        foreach (Thread worker in _workers)
            EnqueueItem(null);

        if (waitForWorkers)
            foreach (Thread worker in _workers)
                worker.Join();
    }

    public void CancelWorkers(bool waitForWorkers)
    {
        lock (_locker)
        {
            _itemQ.Clear();
        }
        StopWorkers(waitForWorkers);
    }

    public void EnqueueItem(Action item)
    {
        lock (_locker)
        {
            _itemQ.Enqueue(item);
            //Check the blocking condition
            Monitor.Pulse(_locker);
        }
    }

    void Consume()
    {
        while (true)
        {
            Action item;
            lock (_locker)
            {
                while (_itemQ.Count == 0)
                    Monitor.Wait(_locker);

                item = _itemQ.Dequeue();
            }
            if (item == null)
                return;
            item();
        }
    }
}