AutoResetEvent 类

参考

定义

命名空间:: System.Threading

程序集:: System.Threading.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

Source:: AutoResetEvent.cs

Source:: AutoResetEvent.cs

Source:: AutoResetEvent.cs

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

表示一个线程同步事件，当发出信号时，释放一个等待线程，然后自动重置。无法继承此类。

public ref class AutoResetEvent sealed : System::Threading::EventWaitHandle

public ref class AutoResetEvent sealed : System::Threading::WaitHandle

public sealed class AutoResetEvent : System.Threading.EventWaitHandle

public sealed class AutoResetEvent : System.Threading.WaitHandle

[System.Runtime.InteropServices.ComVisible(true)]
public sealed class AutoResetEvent : System.Threading.EventWaitHandle

type AutoResetEvent = class
    inherit EventWaitHandle

type AutoResetEvent = class
    inherit WaitHandle

[<System.Runtime.InteropServices.ComVisible(true)>]
type AutoResetEvent = class
    inherit EventWaitHandle

Public NotInheritable Class AutoResetEvent
Inherits EventWaitHandle

Public NotInheritable Class AutoResetEvent
Inherits WaitHandle

继承: Object

WaitHandle

EventWaitHandle
AutoResetEvent

继承: Object

MarshalByRefObject

WaitHandle

EventWaitHandle
AutoResetEvent

继承: Object

MarshalByRefObject

WaitHandle
AutoResetEvent

属性: ComVisibleAttribute

示例

以下示例演示如何使用 AutoResetEvent 一次释放一个线程，方法是每次用户按 Enter 键时调用 Set 方法（基类）。该示例启动三个线程，等待在信号状态创建的 AutoResetEvent。第一个线程会立即释放，因为 AutoResetEvent 已处于信号状态。这会将 AutoResetEvent 重置为非信号状态，以便后续线程阻止。在用户一次发布一个线程之前，不会释放阻止的线程，方法是按 Enter 键。

从第一个 AutoResetEvent释放线程后，等待另一个处于非信号状态创建的 AutoResetEvent。所有三个线程都块，因此必须调用 Set 方法三次才能释放所有线程。

using namespace System;
using namespace System::Threading;

ref class Example
{
private:
    static AutoResetEvent^ event_1 = gcnew AutoResetEvent(true);
    static AutoResetEvent^ event_2 = gcnew AutoResetEvent(false);

    static void ThreadProc()
    {
        String^ name = Thread::CurrentThread->Name;

        Console::WriteLine("{0} waits on AutoResetEvent #1.", name);
        event_1->WaitOne();
        Console::WriteLine("{0} is released from AutoResetEvent #1.", name);

        Console::WriteLine("{0} waits on AutoResetEvent #2.", name);
        event_2->WaitOne();
        Console::WriteLine("{0} is released from AutoResetEvent #2.", name);

        Console::WriteLine("{0} ends.", name);
    }

public:
    static void Demo()
    {
        Console::WriteLine("Press Enter to create three threads and start them.\r\n" +
                           "The threads wait on AutoResetEvent #1, which was created\r\n" +
                           "in the signaled state, so the first thread is released.\r\n" +
                           "This puts AutoResetEvent #1 into the unsignaled state.");
        Console::ReadLine();
            
        for (int i = 1; i < 4; i++)
        {
            Thread^ t = gcnew Thread(gcnew ThreadStart(&ThreadProc));
            t->Name = "Thread_" + i;
            t->Start();
        }
        Thread::Sleep(250);

        for (int i = 0; i < 2; i++)
        {
            Console::WriteLine("Press Enter to release another thread.");
            Console::ReadLine();
            event_1->Set();
            Thread::Sleep(250);
        }

        Console::WriteLine("\r\nAll threads are now waiting on AutoResetEvent #2.");
        for (int i = 0; i < 3; i++)
        {
            Console::WriteLine("Press Enter to release a thread.");
            Console::ReadLine();
            event_2->Set();
            Thread::Sleep(250);
        }

        // Visual Studio: Uncomment the following line.
        //Console::Readline();
    }
};

void main()
{
    Example::Demo();
}

/* This example produces output similar to the following:

Press Enter to create three threads and start them.
The threads wait on AutoResetEvent #1, which was created
in the signaled state, so the first thread is released.
This puts AutoResetEvent #1 into the unsignaled state.

Thread_1 waits on AutoResetEvent #1.
Thread_1 is released from AutoResetEvent #1.
Thread_1 waits on AutoResetEvent #2.
Thread_3 waits on AutoResetEvent #1.
Thread_2 waits on AutoResetEvent #1.
Press Enter to release another thread.

Thread_3 is released from AutoResetEvent #1.
Thread_3 waits on AutoResetEvent #2.
Press Enter to release another thread.

Thread_2 is released from AutoResetEvent #1.
Thread_2 waits on AutoResetEvent #2.

All threads are now waiting on AutoResetEvent #2.
Press Enter to release a thread.

Thread_2 is released from AutoResetEvent #2.
Thread_2 ends.
Press Enter to release a thread.

Thread_1 is released from AutoResetEvent #2.
Thread_1 ends.
Press Enter to release a thread.

Thread_3 is released from AutoResetEvent #2.
Thread_3 ends.
 */

using System;
using System.Threading;

// Visual Studio: Replace the default class in a Console project with 
//                the following class.
class Example
{
    private static AutoResetEvent event_1 = new AutoResetEvent(true);
    private static AutoResetEvent event_2 = new AutoResetEvent(false);

    static void Main()
    {
        Console.WriteLine("Press Enter to create three threads and start them.\r\n" +
                          "The threads wait on AutoResetEvent #1, which was created\r\n" +
                          "in the signaled state, so the first thread is released.\r\n" +
                          "This puts AutoResetEvent #1 into the unsignaled state.");
        Console.ReadLine();
            
        for (int i = 1; i < 4; i++)
        {
            Thread t = new Thread(ThreadProc);
            t.Name = "Thread_" + i;
            t.Start();
        }
        Thread.Sleep(250);

        for (int i = 0; i < 2; i++)
        {
            Console.WriteLine("Press Enter to release another thread.");
            Console.ReadLine();
            event_1.Set();
            Thread.Sleep(250);
        }

        Console.WriteLine("\r\nAll threads are now waiting on AutoResetEvent #2.");
        for (int i = 0; i < 3; i++)
        {
            Console.WriteLine("Press Enter to release a thread.");
            Console.ReadLine();
            event_2.Set();
            Thread.Sleep(250);
        }

        // Visual Studio: Uncomment the following line.
        //Console.Readline();
    }

    static void ThreadProc()
    {
        string name = Thread.CurrentThread.Name;

        Console.WriteLine("{0} waits on AutoResetEvent #1.", name);
        event_1.WaitOne();
        Console.WriteLine("{0} is released from AutoResetEvent #1.", name);

        Console.WriteLine("{0} waits on AutoResetEvent #2.", name);
        event_2.WaitOne();
        Console.WriteLine("{0} is released from AutoResetEvent #2.", name);

        Console.WriteLine("{0} ends.", name);
    }
}

/* This example produces output similar to the following:

Press Enter to create three threads and start them.
The threads wait on AutoResetEvent #1, which was created
in the signaled state, so the first thread is released.
This puts AutoResetEvent #1 into the unsignaled state.

Thread_1 waits on AutoResetEvent #1.
Thread_1 is released from AutoResetEvent #1.
Thread_1 waits on AutoResetEvent #2.
Thread_3 waits on AutoResetEvent #1.
Thread_2 waits on AutoResetEvent #1.
Press Enter to release another thread.

Thread_3 is released from AutoResetEvent #1.
Thread_3 waits on AutoResetEvent #2.
Press Enter to release another thread.

Thread_2 is released from AutoResetEvent #1.
Thread_2 waits on AutoResetEvent #2.

All threads are now waiting on AutoResetEvent #2.
Press Enter to release a thread.

Thread_2 is released from AutoResetEvent #2.
Thread_2 ends.
Press Enter to release a thread.

Thread_1 is released from AutoResetEvent #2.
Thread_1 ends.
Press Enter to release a thread.

Thread_3 is released from AutoResetEvent #2.
Thread_3 ends.
 */

Imports System.Threading

' Visual Studio: Replace the default class in a Console project with 
'                the following class.
Class Example

    Private Shared event_1 As New AutoResetEvent(True)
    Private Shared event_2 As New AutoResetEvent(False)

    <MTAThread()> _
    Shared Sub Main()
    
        Console.WriteLine("Press Enter to create three threads and start them." & vbCrLf & _
                          "The threads wait on AutoResetEvent #1, which was created" & vbCrLf & _
                          "in the signaled state, so the first thread is released." & vbCrLf & _
                          "This puts AutoResetEvent #1 into the unsignaled state.")
        Console.ReadLine()
            
        For i As Integer = 1 To 3
            Dim t As New Thread(AddressOf ThreadProc)
            t.Name = "Thread_" & i
            t.Start()
        Next
        Thread.Sleep(250)

        For i As Integer = 1 To 2
            Console.WriteLine("Press Enter to release another thread.")
            Console.ReadLine()

            event_1.Set()
            Thread.Sleep(250)
        Next

        Console.WriteLine(vbCrLf & "All threads are now waiting on AutoResetEvent #2.")
        For i As Integer = 1 To 3
            Console.WriteLine("Press Enter to release a thread.")
            Console.ReadLine()

            event_2.Set()
            Thread.Sleep(250)
        Next

        ' Visual Studio: Uncomment the following line.
        'Console.Readline()
    End Sub

    Shared Sub ThreadProc()
    
        Dim name As String = Thread.CurrentThread.Name

        Console.WriteLine("{0} waits on AutoResetEvent #1.", name)
        event_1.WaitOne()
        Console.WriteLine("{0} is released from AutoResetEvent #1.", name)

        Console.WriteLine("{0} waits on AutoResetEvent #2.", name)
        event_2.WaitOne()
        Console.WriteLine("{0} is released from AutoResetEvent #2.", name)

        Console.WriteLine("{0} ends.", name)
    End Sub
End Class

' This example produces output similar to the following:
'
'Press Enter to create three threads and start them.
'The threads wait on AutoResetEvent #1, which was created
'in the signaled state, so the first thread is released.
'This puts AutoResetEvent #1 into the unsignaled state.
'
'Thread_1 waits on AutoResetEvent #1.
'Thread_1 is released from AutoResetEvent #1.
'Thread_1 waits on AutoResetEvent #2.
'Thread_3 waits on AutoResetEvent #1.
'Thread_2 waits on AutoResetEvent #1.
'Press Enter to release another thread.
'
'Thread_3 is released from AutoResetEvent #1.
'Thread_3 waits on AutoResetEvent #2.
'Press Enter to release another thread.
'
'Thread_2 is released from AutoResetEvent #1.
'Thread_2 waits on AutoResetEvent #2.
'
'All threads are now waiting on AutoResetEvent #2.
'Press Enter to release a thread.
'
'Thread_2 is released from AutoResetEvent #2.
'Thread_2 ends.
'Press Enter to release a thread.
'
'Thread_1 is released from AutoResetEvent #2.
'Thread_1 ends.
'Press Enter to release a thread.
'
'Thread_3 is released from AutoResetEvent #2.
'Thread_3 ends.

注解

使用 AutoResetEvent、ManualResetEvent和 EventWaitHandle 进行线程交互（或线程信号）。有关详细信息，请参阅线程交互。

线程通过调用 AutoResetEvent.WaitOne来等待信号。如果 AutoResetEvent 处于非信号状态，则线程会阻塞，直到调用 AutoResetEvent.Set。调用 Set 信号 AutoResetEvent 释放等待线程。 AutoResetEvent 保持信号，直到调用 Reset 或释放单个等待线程，此时它会自动返回到非信号状态。

如果没有线程在 AutoResetEvent 进入信号状态时等待，则状态将保持信号，直到线程观察信号（通过调用 WaitOne）。该线程不阻止：AutoResetEvent 立即释放线程并返回到非信号状态。

重要

不能保证每次调用 Set 方法都会释放线程。如果两个调用在一起太接近，以便在释放线程之前进行第二次调用，则只释放一个线程。就好像第二次调用没有发生一样。此外，如果没有等待的线程且 AutoResetEvent 已发出信号，则调用将不起作用 Set。

可以通过将布尔值传递给构造函数来控制 AutoResetEvent 的初始状态：如果发出初始状态并 false 则 true。

AutoResetEvent 还可用于 staticWaitAll 和 WaitAny 方法。

AutoResetEvent 派生自 EventWaitHandle 类。 AutoResetEvent 在功能上等效于使用 EventResetMode.AutoReset创建的 EventWaitHandle。

注意

与 AutoResetEvent 类不同，EventWaitHandle 类提供对命名系统同步事件的访问权限。

重要

此类型实现 IDisposable 接口。使用完该类型后，应直接或间接释放它。若要直接释放类型，请在 try/catch 块中调用其 Dispose 方法。若要间接处理它，请使用语言构造（如 using（在 C# 中）或 Using（在 Visual Basic 中）。有关详细信息，请参阅 IDisposable 接口页上的“使用实现 IDisposable 的对象”部分。

构造函数

AutoResetEvent(Boolean)

使用布尔值初始化 AutoResetEvent 类的新实例，该值指示是否将初始状态设置为信号。

字段

WaitTimeout

指示在发出任何等待句柄之前，WaitAny(WaitHandle[], Int32, Boolean) 操作超时。此字段为常量。

(继承自 WaitHandle)

属性

Handle	已过时. 已过时. 获取或设置本机操作系统句柄。 (继承自 WaitHandle)
SafeWaitHandle	获取或设置本机操作系统句柄。 (继承自 WaitHandle)

方法

Close()	释放当前 WaitHandle持有的所有资源。 (继承自 WaitHandle)
CreateObjRef(Type)	创建一个对象，其中包含生成用于与远程对象通信的代理所需的所有相关信息。 (继承自 MarshalByRefObject)
Dispose()	释放 WaitHandle 类的当前实例使用的所有资源。 (继承自 WaitHandle)
Dispose(Boolean)	在派生类中重写时，释放 WaitHandle使用的非托管资源，并选择性地释放托管资源。 (继承自 WaitHandle)
Equals(Object)	确定指定的对象是否等于当前对象。 (继承自 Object)
GetAccessControl()	获取一个 EventWaitHandleSecurity 对象，该对象表示由当前 EventWaitHandle 对象表示的命名系统事件的访问控制安全性。 (继承自 EventWaitHandle)
GetHashCode()	用作默认哈希函数。 (继承自 Object)
GetLifetimeService()	已过时. 检索控制此实例的生存期策略的当前生存期服务对象。 (继承自 MarshalByRefObject)
GetType()	获取当前实例的 Type。 (继承自 Object)
InitializeLifetimeService()	已过时. 获取生存期服务对象来控制此实例的生存期策略。 (继承自 MarshalByRefObject)
MemberwiseClone()	创建当前 Object的浅表副本。 (继承自 Object)
MemberwiseClone(Boolean)	创建当前 MarshalByRefObject 对象的浅表副本。 (继承自 MarshalByRefObject)
Reset()	将事件的状态设置为非对齐状态，这会导致线程阻止。
Reset()	将事件的状态设置为非对齐状态，导致线程被阻止。 (继承自 EventWaitHandle)
Set()	将事件的状态设置为信号，这最多允许一个等待线程继续。
Set()	将事件的状态设置为信号，允许一个或多个等待线程继续。 (继承自 EventWaitHandle)
SetAccessControl(EventWaitHandleSecurity)	设置命名系统事件的访问控制安全性。 (继承自 EventWaitHandle)
ToString()	返回一个表示当前对象的字符串。 (继承自 Object)
WaitOne()	阻止当前线程，直到当前 WaitHandle 收到信号。 (继承自 WaitHandle)
WaitOne(Int32)	阻止当前线程，直到当前 WaitHandle 接收信号，使用 32 位有符号整数指定时间间隔（以毫秒为单位）。 (继承自 WaitHandle)
WaitOne(Int32, Boolean)	阻止当前线程，直到当前 WaitHandle 收到信号，使用 32 位有符号整数指定时间间隔，并指定是否在等待之前退出同步域。 (继承自 WaitHandle)
WaitOne(TimeSpan)	阻止当前线程，直到当前实例收到信号，使用 TimeSpan 指定时间间隔。 (继承自 WaitHandle)
WaitOne(TimeSpan, Boolean)	阻止当前线程，直到当前实例收到信号，使用 TimeSpan 指定时间间隔，并指定是否在等待之前退出同步域。 (继承自 WaitHandle)

显式接口实现

IDisposable.Dispose()

此 API 支持产品基础结构，不能在代码中直接使用。

释放 WaitHandle使用的所有资源。

(继承自 WaitHandle)

扩展方法

GetAccessControl(EventWaitHandle)	返回指定 `handle`的安全描述符。
SetAccessControl(EventWaitHandle, EventWaitHandleSecurity)	设置指定事件等待句柄的安全描述符。
GetSafeWaitHandle(WaitHandle)	获取本机操作系统等待句柄的安全句柄。
SetSafeWaitHandle(WaitHandle, SafeWaitHandle)	设置本机操作系统等待句柄的安全句柄。

适用于

线程安全性

此类是线程安全的。

通过

AutoResetEvent 类

定义

示例

注解

构造函数

字段

属性

方法

显式接口实现

扩展方法

适用于

线程安全性

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