【Windows Phone】AutoResetEvent && ManualResetEvent

1. 继承关系 （在System.Threading命名空间中）

    AutoResetEvent -> EventWaitHandle -> WaitHandle

    ManualResetEvent -> EventWaitHandle -> WaitHandle

2. WaitHandle的属性和方法

2.1 属性

      SafeWaitHandle - 安全等待句柄

      WaitTimeout - 等待时长

2.2 方法

      WaitOne()

      WaitOne(System.TimeSpan timeout)

      WaitOne(int millisecondsTimeout)

      以上三个方法的作用是阻塞当前线程，直到线程收到信号后唤醒。重载的参数是一个时间段，设置了线程阻塞的超时限制，-1为时间无限。

      WaitAny(System.Threading.WaitHandle[])

      WaitAny(System.Threading.WaitHandle[], System.TimeSpan)

      WaitAny(System.Threading.WaitHandle[], int)

      以上三个方法的作用是阻塞当前线程，直到线程收到参数中WaitHandle的任一信号后唤醒。

      WaitAll(System.Threading.WaitHandle[])

      WaitAll(System.Threading.WaitHandle[], System.TimeSpan)

      WaitAll(System.Threading.WaitHandle[], int)

      以上三个方法的作用是阻塞当前线程，直到线程收到参数中WaitHandle的所有信号后唤醒。

      Dispose()

      virtual Close()

      这两个方法是释放自己句柄相关的所有系统资源。

3. EventWaitHandle

    WaitOne() - 阻塞当前线程，返回值表示成功失败

    Set() - 设置对应线程状态为唤醒状态，返回值表示成功失败

    Reset() - 设置对应线程状态为非唤醒状态，引发线程阻塞，返回值表示成功失败

4. AutoResetEvent和ManualResetEvent的区别

    AutoResetEvent正如其名字一样，会自动Reset对应线程的状态；而ManualResetEvent则不会自动重置对应线程的状态。所以在调用Set()操作后，AutoResetEvent在唤醒一个等待线程之后，会重新将状态置为false(阻塞)，因此仅会有一个等待线程被唤醒；而ManualResetEvent在调用Set()操作之后，如果不手动重置状态，状态就会保持true(唤醒)，所有等待线程都将被唤醒。

5. AutoResetEvent和ManualResetEvent构造bool参数的含义：

    true:  Initialize status as received signal.

    false: Initialize status as non received signal.

6. 实例：

6.1. UI部分

        <!--ContentPanel - 在此处放置其他内容-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <StackPanel Orientation="Vertical">
                <ListBox Name="Messages" Height="400"></ListBox>
                <StackPanel Orientation="Horizontal">
                    <Button Name="Auto" Content="Auto Start" Click="Auto_Click" Width="230"></Button>
                    <Button Content="Signal" Click="Button_Click" Width="230"></Button>
                </StackPanel>
                <StackPanel Orientation="Horizontal">
                    <Button Name="Manual" Content="Manual Start" Click="Manual_Click" Width="230"></Button>
                    <Button Content="Signal" Click="Button_Click" Width="230"></Button>
                </StackPanel>
            </StackPanel>
        </Grid>

 

6.2. 实现部分：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using System.Threading;

namespace ResetEventTest
{
    public partial class MainPage : PhoneApplicationPage
    {
        // Parameter: true - Initialize status as received signal.
        //           false - Initialized status as not received signal.
        private AutoResetEvent _autoResetEvent = new AutoResetEvent(false);

        // Parameter: true - Initialize status as received signal.
        //           false - Initialized status as not received signal.
        private ManualResetEvent _manualResetEvent = new ManualResetEvent(false);

        private bool _autoReset = true;

        public MainPage()
        {
            InitializeComponent();
        }

        private void Auto_Click(object sender, RoutedEventArgs e)
        {
            Messages.Items.Clear();
            _autoReset = true;
            for (int i = 0; i < 4; ++i)
            {
                Thread thread = new Thread(new ParameterizedThreadStart(ThreadProc));
                thread.Start(i);
            }
        }

        private void Manual_Click(object sender, RoutedEventArgs e)
        {
            Messages.Items.Clear();
            _autoReset = false;
            for (int i = 0; i < 4; ++i)
            {
                Thread thread = new Thread(new ParameterizedThreadStart(ThreadProc));
                thread.Start(i);
            }
        }

        private void ThreadProc(object obj)
        {
            int index = (int)obj;
            if (_autoReset)
            {
                _autoResetEvent.WaitOne();
                Deployment.Current.Dispatcher.BeginInvoke(() => { Messages.Items.Add(new TextBlock { Text = "Thread " + index + " wake up by auto reset way!" }); });
            }
            else
            {
                _manualResetEvent.WaitOne();
                Deployment.Current.Dispatcher.BeginInvoke(() => { Messages.Items.Add(new TextBlock { Text = "Thread " + index + " wake up by manual reset way!" }); });
            }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            if (_autoReset)
            {
                _autoResetEvent.Set();
            }
            else
            {
                _manualResetEvent.Set();
            }
        }
    }
}

 

7. 官方实例：http://msdn.microsoft.com/zh-cn/library/system.threading.eventresetmode.aspx