WaitHandle.WaitTimeout Campo

Definizione

Spazio dei nomi:

System.Threading

Assembly:

System.Runtime.dll

Assembly:

netstandard.dll

Assembly:

mscorlib.dll

Indica che si è verificato il timeout di un'operazione WaitAny(WaitHandle[], Int32, Boolean) prima della segnalazione di uno degli handle di attesa. Questo campo è costante.

public: int WaitTimeout = 258;

public const int WaitTimeout = 258;

val mutable WaitTimeout : int

Public Const WaitTimeout As Integer  = 258

Valore del campo

Value = 258

Int32

Esempio

Nell'esempio di codice seguente viene illustrato come usare il pool di thread per cercare contemporaneamente un file su più dischi. Per considerazioni relative allo spazio, viene cercata solo la directory radice di ogni disco.

using namespace System;
using namespace System::IO;
using namespace System::Threading;
ref class Search
{
private:

   // Maintain state information to pass to FindCallback.
   ref class State
   {
   public:
      AutoResetEvent^ autoEvent;
      String^ fileName;
      State( AutoResetEvent^ autoEvent, String^ fileName )
         : autoEvent( autoEvent ), fileName( fileName )
      {}

   };


public:
   array<AutoResetEvent^>^autoEvents;
   array<String^>^diskLetters;

   // Search for stateInfo->fileName.
   void FindCallback( Object^ state )
   {
      State^ stateInfo = dynamic_cast<State^>(state);
      
      // Signal if the file is found.
      if ( File::Exists( stateInfo->fileName ) )
      {
         stateInfo->autoEvent->Set();
      }
   }

   Search()
   {
      
      // Retrieve an array of disk letters.
      diskLetters = Environment::GetLogicalDrives();
      autoEvents = gcnew array<AutoResetEvent^>(diskLetters->Length);
      for ( int i = 0; i < diskLetters->Length; i++ )
      {
         autoEvents[ i ] = gcnew AutoResetEvent( false );

      }
   }


   // Search for fileName in the root directory of all disks.
   void FindFile( String^ fileName )
   {
      for ( int i = 0; i < diskLetters->Length; i++ )
      {
         Console::WriteLine(  "Searching for {0} on {1}.", fileName, diskLetters[ i ] );
         ThreadPool::QueueUserWorkItem( gcnew WaitCallback( this, &Search::FindCallback ), gcnew State( autoEvents[ i ],String::Concat( diskLetters[ i ], fileName ) ) );

      }
      
      // Wait for the first instance of the file to be found.
      int index = WaitHandle::WaitAny( autoEvents, 3000, false );
      if ( index == WaitHandle::WaitTimeout )
      {
         Console::WriteLine( "\n{0} not found.", fileName );
      }
      else
      {
         Console::WriteLine( "\n{0} found on {1}.", fileName, diskLetters[ index ] );
      }
   }

};

int main()
{
   Search^ search = gcnew Search;
   search->FindFile( "SomeFile.dat" );
}

using System;
using System.IO;
using System.Threading;

class Test
{
    static void Main()
    {
        Search search = new Search();
        search.FindFile("SomeFile.dat");
    }
}

class Search
{
    // Maintain state information to pass to FindCallback.
    class State
    {
        public AutoResetEvent autoEvent;
        public string         fileName;

        public State(AutoResetEvent autoEvent, string fileName)
        {
            this.autoEvent    = autoEvent;
            this.fileName     = fileName;
        }
    }

    AutoResetEvent[] autoEvents;
    String[] diskLetters;

    public Search()
    {
        // Retrieve an array of disk letters.
        diskLetters = Environment.GetLogicalDrives();

        autoEvents = new AutoResetEvent[diskLetters.Length];
        for(int i = 0; i < diskLetters.Length; i++)
        {
            autoEvents[i] = new AutoResetEvent(false);
        }
    }

    // Search for fileName in the root directory of all disks.
    public void FindFile(string fileName)
    {
        for(int i = 0; i < diskLetters.Length; i++)
        {
            Console.WriteLine("Searching for {0} on {1}.",
                fileName, diskLetters[i]);
            ThreadPool.QueueUserWorkItem(
                new WaitCallback(FindCallback), 
                new State(autoEvents[i], diskLetters[i] + fileName));
        }

        // Wait for the first instance of the file to be found.
        int index = WaitHandle.WaitAny(autoEvents, 3000, false);
        if(index == WaitHandle.WaitTimeout)
        {
            Console.WriteLine("\n{0} not found.", fileName);
        }
        else
        {
            Console.WriteLine("\n{0} found on {1}.", fileName,
                diskLetters[index]);
        }
    }

    // Search for stateInfo.fileName.
    void FindCallback(object state)
    {
        State stateInfo = (State)state;

        // Signal if the file is found.
        if(File.Exists(stateInfo.fileName))
        {
            stateInfo.autoEvent.Set();
        }
    }
}

Imports System.IO
Imports System.Threading

Public Class Test

    <MTAThread> _
    Shared Sub Main()
        Dim search As New Search()
        search.FindFile("SomeFile.dat")
    End Sub    
End Class

Public Class Search

    ' Maintain state information to pass to FindCallback.
    Class State
        Public autoEvent As AutoResetEvent 
        Public fileName As String         

        Sub New(anEvent As AutoResetEvent, fName As String)
            autoEvent = anEvent
            fileName = fName
        End Sub
    End Class

    Dim autoEvents() As AutoResetEvent
    Dim diskLetters() As String

    Sub New()

        ' Retrieve an array of disk letters.
        diskLetters = Environment.GetLogicalDrives()

        autoEvents = New AutoResetEvent(diskLetters.Length - 1) {}
        For i As Integer = 0 To diskLetters.Length - 1
            autoEvents(i) = New AutoResetEvent(False)
        Next i
    End Sub    
    
    ' Search for fileName in the root directory of all disks.
    Sub FindFile(fileName As String)
        For i As Integer = 0 To diskLetters.Length - 1
            Console.WriteLine("Searching for {0} on {1}.", _
                fileName, diskLetters(i))
        
            ThreadPool.QueueUserWorkItem(AddressOf FindCallback, _ 
                New State(autoEvents(i), diskLetters(i) & fileName))
        Next i

        ' Wait for the first instance of the file to be found.
        Dim index As Integer = _
            WaitHandle.WaitAny(autoEvents, 3000, False)
        If index = WaitHandle.WaitTimeout
            Console.WriteLine(vbCrLf & "{0} not found.", fileName)
        Else
            Console.WriteLine(vbCrLf & "{0} found on {1}.", _
                fileName, diskLetters(index))
        End If
    End Sub

    ' Search for stateInfo.fileName.
    Sub FindCallback(state As Object)
        Dim stateInfo As State = DirectCast(state, State)

        ' Signal if the file is found.
        If File.Exists(stateInfo.fileName) Then
            stateInfo.autoEvent.Set()
        End If
    End Sub

End Class

Commenti

Questo campo è uno dei possibili valori restituiti di WaitAny .