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ManualResetEventSlim Class

Provides a slimmed down version of ManualResetEvent.

System.Object
  System.Threading.ManualResetEventSlim

Namespace:  System.Threading
Assembly:  mscorlib (in mscorlib.dll)

[ComVisibleAttribute(false)]
[DebuggerDisplayAttribute("Set = {IsSet}")]
[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
	ExternalThreading = true)]
public class ManualResetEventSlim : IDisposable

The ManualResetEventSlim type exposes the following members.

  NameDescription
Public methodSupported by Portable Class LibraryManualResetEventSlim()Initializes a new instance of the ManualResetEventSlim class with an initial state of nonsignaled.
Public methodSupported by Portable Class LibraryManualResetEventSlim(Boolean)Initializes a new instance of the ManualResetEventSlim class with a Boolean value indicating whether to set the intial state to signaled.
Public methodSupported by Portable Class LibraryManualResetEventSlim(Boolean, Int32)Initializes a new instance of the ManualResetEventSlim class with a Boolean value indicating whether to set the intial state to signaled and a specified spin count.
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  NameDescription
Public propertySupported by Portable Class LibraryIsSetGets whether the event is set.
Public propertySupported by Portable Class LibrarySpinCountGets the number of spin waits that will be occur before falling back to a kernel-based wait operation.
Public propertySupported by Portable Class LibraryWaitHandleGets the underlying WaitHandle object for this ManualResetEventSlim.
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  NameDescription
Public methodSupported by Portable Class LibraryDispose()Releases all resources used by the current instance of the ManualResetEventSlim class.
Protected methodSupported by Portable Class LibraryDispose(Boolean)Releases the unmanaged resources used by the ManualResetEventSlim, and optionally releases the managed resources.
Public methodSupported by Portable Class LibraryEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Portable Class LibraryGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Portable Class LibraryResetSets the state of the event to nonsignaled, which causes threads to block.
Public methodSupported by Portable Class LibrarySetSets the state of the event to signaled, which allows one or more threads waiting on the event to proceed.
Public methodSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodSupported by Portable Class LibraryWait()Blocks the current thread until the current ManualResetEventSlim is set.
Public methodSupported by Portable Class LibraryWait(CancellationToken)Blocks the current thread until the current ManualResetEventSlim receives a signal, while observing a CancellationToken.
Public methodSupported by Portable Class LibraryWait(Int32)Blocks the current thread until the current ManualResetEventSlim is set, using a 32-bit signed integer to measure the time interval.
Public methodSupported by Portable Class LibraryWait(TimeSpan)Blocks the current thread until the current ManualResetEventSlim is set, using a TimeSpan to measure the time interval.
Public methodSupported by Portable Class LibraryWait(Int32, CancellationToken)Blocks the current thread until the current ManualResetEventSlim is set, using a 32-bit signed integer to measure the time interval, while observing a CancellationToken.
Public methodSupported by Portable Class LibraryWait(TimeSpan, CancellationToken)Blocks the current thread until the current ManualResetEventSlim is set, using a TimeSpan to measure the time interval, while observing a CancellationToken.
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You can use this class for better performance than ManualResetEvent when wait times are expected to be very short, and when the event does not cross a process boundary. ManualResetEventSlim uses busy spinning for a short time while it waits for the event to become signaled. When wait times are short, spinning can be much less expensive than waiting by using wait handles. However, if the event does not become signaled within a certain period of time, ManualResetEventSlim resorts to a regular event handle wait.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization | ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example shows how to use a ManualResetEventSlim. For more information about the use of SpinCount and other best practices concerning the use of this type, see ManualResetEvent and ManualResetEventSlim.

using System;
using System.Threading;
using System.Threading.Tasks;
class MRESDemo
{

    static void Main()
    {
        MRES_SetWaitReset();
        MRES_SpinCountWaitHandle();
    }
    // Demonstrates: 
    //      ManualResetEventSlim construction 
    //      ManualResetEventSlim.Wait() 
    //      ManualResetEventSlim.Set() 
    //      ManualResetEventSlim.Reset() 
    //      ManualResetEventSlim.IsSet 
    static void MRES_SetWaitReset()
    {
        ManualResetEventSlim mres1 = new ManualResetEventSlim(false); // initialize as unsignaled
        ManualResetEventSlim mres2 = new ManualResetEventSlim(false); // initialize as unsignaled
        ManualResetEventSlim mres3 = new ManualResetEventSlim(true);  // initialize as signaled 

        // Start an asynchronous Task that manipulates mres3 and mres2 
        var observer = Task.Factory.StartNew(() =>
        {
            mres1.Wait();
            Console.WriteLine("observer sees signaled mres1!");
            Console.WriteLine("observer resetting mres3...");
            mres3.Reset(); // should switch to unsignaled
            Console.WriteLine("observer signalling mres2");
            mres2.Set();
        });

        Console.WriteLine("main thread: mres3.IsSet = {0} (should be true)", mres3.IsSet);
        Console.WriteLine("main thread signalling mres1");
        mres1.Set(); // This will "kick off" the observer Task
        mres2.Wait(); // This won't return until observer Task has finished resetting mres3
        Console.WriteLine("main thread sees signaled mres2!");
        Console.WriteLine("main thread: mres3.IsSet = {0} (should be false)", mres3.IsSet);

        // It's good form to Dispose() a ManualResetEventSlim when you're done with it
        observer.Wait(); // make sure that this has fully completed
        mres1.Dispose();
        mres2.Dispose();
        mres3.Dispose();
    }

    // Demonstrates: 
    //      ManualResetEventSlim construction w/ SpinCount 
    //      ManualResetEventSlim.WaitHandle 
    static void MRES_SpinCountWaitHandle()
    {
        // Construct a ManualResetEventSlim with a SpinCount of 1000 
        // Higher spincount => longer time the MRES will spin-wait before taking lock
        ManualResetEventSlim mres1 = new ManualResetEventSlim(false, 1000);
        ManualResetEventSlim mres2 = new ManualResetEventSlim(false, 1000);

        Task bgTask = Task.Factory.StartNew(() =>
        {
            // Just wait a little
            Thread.Sleep(100);

            // Now signal both MRESes
            Console.WriteLine("Task signalling both MRESes");
            mres1.Set();
            mres2.Set();
        });

        // A common use of MRES.WaitHandle is to use MRES as a participant in  
        // WaitHandle.WaitAll/WaitAny.  Note that accessing MRES.WaitHandle will 
        // result in the unconditional inflation of the underlying ManualResetEvent.
        WaitHandle.WaitAll(new WaitHandle[] { mres1.WaitHandle, mres2.WaitHandle });
        Console.WriteLine("WaitHandle.WaitAll(mres1.WaitHandle, mres2.WaitHandle) completed.");

        // Clean up
        bgTask.Wait();
        mres1.Dispose();
        mres2.Dispose();
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

All public and protected members of ManualResetEventSlim are thread-safe and may be used concurrently from multiple threads, with the exception of Dispose, which must only be used when all other operations on the ManualResetEventSlim have completed, and Reset, which should only be used when no other threads are accessing the event.

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