backgroundscheduler.cs

HeyCacher 高性能缓存方案(带源码) 1. 文件的所有权益归上传用户所有 2. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途 3. CSDN下载频道仅提供交流平台

//===============================================================================
// CSDN HeyCache 
//===============================================================================
// 修改记录：[按最后修改时间倒排序]
// 2007.06.11 by tangwei
//
// 代码来源：参考于dotnet企业库3.0版
//===============================================================================
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;

namespace HeyCacher.Components.Scavenger
{
    /// <summary>
    /// 后台缓存回收器
    /// </summary>
    public class BackgroundScheduler
    {
        private ProducerConsumerQueue inputQueue = new ProducerConsumerQueue();
        private Thread inputQueueThread;
        private ExpirationTask expirer;
        private bool isActive;
        private bool running;

        /// <summary>
        /// Initialize a new instance of the <see cref="BackgroundScheduler"/> with a <see cref="ExpirationTask"/> and a <see cref="ScavengerTask"/>.
        /// </summary>
        /// <param name="expirer">The expiration task to use.</param>
        /// <param name="scavenger">The scavenger task to use.</param>
        /// <param name="instrumentationProvider">The instrumentation provider to use.</param>
        public BackgroundScheduler(ExpirationTask expirer)
        {
            this.expirer = expirer;

            ThreadStart queueReader = new ThreadStart(QueueReader);
            inputQueueThread = new Thread(queueReader);
            inputQueueThread.IsBackground = true;
        }

        /// <summary>
        /// Starts the scavenger.
        /// </summary>
        public void Start()
        {
            running = true;
            inputQueueThread.Start();
        }

        /// <summary>
        /// Stops the scavenger.
        /// </summary>
        public void Stop()
        {
            running = false;
            inputQueueThread.Interrupt();
        }

        /// <summary>
        /// Determines if the scavenger is active.
        /// </summary>
        /// <value>
        /// <see langword="true"/> if the scavenger is active; otherwise, <see langword="false"/>.
        /// </value>
        public bool IsActive
        {
            get { return isActive; }
        }

        /// <summary>
        /// Queues a message that the expiration timeout has expired.
        /// </summary>
        /// <param name="notUsed">Ignored.</param>
        public void ExpirationTimeoutExpired(object notUsed)
        {
            inputQueue.Enqueue(new ExpirationTimeoutExpiredMsg(this));
        }
        public void ExpirationTimeoutExpired(object notUsed, System.Timers.ElapsedEventArgs e)
        {
            inputQueue.Enqueue(new ExpirationTimeoutExpiredMsg(this));
        }

        internal void DoExpirationTimeoutExpired()
        {
            expirer.DoExpirations();
        }

        private void QueueReader()
        {
            isActive = true;
            while (running)
            {
                IQueueMessage msg = inputQueue.Dequeue() as IQueueMessage;
                try
                {
                    if (msg == null)
                    {
                        continue;
                    }

                    msg.Run();
                }
                catch (ThreadInterruptedException ex)
                {
                    Caches.log.Warn("回收器在逐一执行队列中每个失效判定的时候出现了一个线程错误，通常可能是所用时间太长引起的", ex);
                }
                catch (Exception ex)
                {
                    Caches.log.Warn("回收器在逐一执行队列中每个失效判定的时候出现了一个未知错误，通常可能是执行失效判定引起的", ex);
                }
            }
            isActive = false;
        }
    }
}