xenadmin/XenModel/Actions/ProduceConsumerQueue.cs

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using System;
using System.Collections.Generic;
using System.Threading;

namespace XenAdmin.Actions
{
    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();
            }
        }
    }
}