ManualResetEventSlim Class

Provides a slimmed down version of ManualResetEvent.

System.Object
  System.Threading.ManualResetEventSlim

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

'Declaration
<ComVisibleAttribute(False)> _
<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization := True,  _
	ExternalThreading := True)> _
Public Class ManualResetEventSlim _
	Implements IDisposable

The ManualResetEventSlim type exposes the following members.

  NameDescription
Public methodManualResetEventSlimInitializes a new instance of the ManualResetEventSlim class with an initial state of nonsignaled.
Public methodManualResetEventSlim(Boolean)Initializes a new instance of the ManualResetEventSlim class with a Boolean value indicating whether to set the intial state to signaled.
Public methodManualResetEventSlim(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 propertyIsSetGets whether the event is set.
Public propertySpinCountGets the number of spin waits that will be occur before falling back to a kernel-based wait operation.
Public propertyWaitHandleGets the underlying WaitHandle object for this ManualResetEventSlim.
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  NameDescription
Public methodDisposeReleases all resources used by the current instance of the ManualResetEventSlim class.
Protected methodDispose(Boolean)When overridden in a derived class, releases the unmanaged resources used by the ManualResetEventSlim, and optionally releases the managed resources.
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodResetSets the state of the event to nonsignaled, which causes threads to block.
Public methodSetSets the state of the event to signaled, which allows one or more threads waiting on the event to proceed.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodWaitBlocks the current thread until the current ManualResetEventSlim is set.
Public methodWait(CancellationToken)Blocks the current thread until the current ManualResetEventSlim receives a signal, while observing a CancellationToken.
Public methodWait(Int32)Blocks the current thread until the current ManualResetEventSlim is set, using a 32-bit signed integer to measure the time interval.
Public methodWait(TimeSpan)Blocks the current thread until the current ManualResetEventSlim is set, using a TimeSpan to measure the time interval.
Public methodWait(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 methodWait(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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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.


Imports System.Threading
Imports System.Threading.Tasks
Module MRESDemo

    Sub Main()

    End Sub
    ' Demonstrates:
    ' ManualResetEventSlim construction
    ' ManualResetEventSlim.Wait()
    ' ManualResetEventSlim.Set()
    ' ManualResetEventSlim.Reset()
    ' ManualResetEventSlim.IsSet
    Private Sub MRES_SetWaitReset()
        ' initialize as unsignaled
        Dim mres1 As New ManualResetEventSlim(False)
        ' initialize as unsignaled
        Dim mres2 As New ManualResetEventSlim(False)
        ' initialize as signaled
        Dim mres3 As New ManualResetEventSlim(True)

        ' Start an asynchronous Task that manipulates mres3 and mres2
        Dim observer = Task.Factory.StartNew(
            Sub()
                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]()
            End Sub)

        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)

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

    ' Demonstrates:
    ' ManualResetEventSlim construction w/ SpinCount
    ' ManualResetEventSlim.WaitHandle
    Private Sub MRES_SpinCountWaitHandle()
        ' Construct a ManualResetEventSlim with a SpinCount of 1000
        ' Higher spincount => longer time the MRES will spin-wait before taking lock
        Dim mres1 As New ManualResetEventSlim(False, 1000)
        Dim mres2 As New ManualResetEventSlim(False, 1000)

        Dim bgTask As Task = Task.Factory.StartNew(
            Sub()
                ' Just wait a little
                Thread.Sleep(100)

                ' Now signal both MRESes
                Console.WriteLine("Task signalling both MRESes")
                mres1.[Set]()
                mres2.[Set]()
            End Sub)

        ' 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.")

        ' Wait for bgTask to complete and clean up
        bgTask.Wait()
        mres1.Dispose()
        mres2.Dispose()
    End Sub
End Module


.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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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