Il modo migliore per richiamare qualsiasi codice cross-threaded?

Question

So che questo problema è stato fatto prima, ma sto cercando un modo per:

1. semplificare la creazione di codice cross-threaded di sicurezza.
2. riutilizzare questo codice in qualsiasi situazione (senza riferimenti a Windows Form).

Ecco quello che ho finora, ma voglio rimuovere i riferimenti di Windows Form. Qualche idea?

public delegate void SafeInvokeDelegate(System.Action action); 
public class SafeInvoke 
{ 
    private readonly System.Windows.Forms.Control _threadControl; 

    public SafeInvoke() 
    { 
     _threadControl = new System.Windows.Forms.Control(); 
    } 

    public void Invoke(System.Action action) 
    { 
     if (_threadControl.InvokeRequired) 
      _threadControl.Invoke(new SafeInvokeDelegate(Invoke), new object[] {action}); 
     else if (action != null) action(); 
    } 
} 

La classe di cui sopra potrebbe essere usata in questo modo:

SafeInvoke _safeInvoker = new SafeInvoke(); 
void SafeClearItems() 
{ 
    _safeInvoker.Invoke(delegate 
     { 
      listView1.Items.Clear(); 
     }); 
} 

Come dovrei togliere lo System.Windows.Forms.Control nella classe SafeInvoke ma mantenere la stessa funzionalità?

Answer 1

È anche possibile utilizzare un metodo di estensione e lambda per rendere il codice molto più pulito.

using System.ComponentModel; 
public static class ISynchronizeInvokeExtensions 
{ 
    public static void InvokeEx<T>(this T @this, Action<T> action) where T : ISynchronizeInvoke 
    { 
    if (@this.InvokeRequired) 
    { 
     @this.Invoke(action, new object[] { @this }); 
    } 
    else 
    { 
     action(@this); 
    } 
    } 
} 

Così ora si può utilizzare su qualsiasi InvokeEx ISynchronizeInvoke ed essere in grado di accedere alle proprietà e campi di attuazione di classe.

this.InvokeEx(f => f.listView1.Items.Clear()); 

Answer 2

Utilizzare ISynchronizeInvoke anziché Control. Questa è l'interfaccia con gli strumenti Control con Invoke/BeginInvoke/EndInvoke/InvokeRequired.

Un'alternativa è quella di utilizzare SynchronizationContext.Current - che è quello che utilizza gli BackgroundWorker, credo.

Answer 3

Eccolo in VB.net, molto simile alla risposta di Samuele. Ho quattro sovraccarichi a seconda che si voglia una subroutine o una funzione e se ci sia o meno un parametro. Sarebbe facile aggiungere più sovraccarichi per più parametri. VB.Net è in grado di dedurre i tipi.

Module ISynchronizeInvokeExtensions 
    Public Delegate Function GenericLambdaFunctionWithParam(Of InputType, OutputType)(ByVal input As InputType) As OutputType 
    Private Delegate Function InvokeLambdaFunctionCallback(Of InputType, OutputType)(ByVal f As GenericLambdaFunctionWithParam(Of InputType, OutputType), ByVal input As InputType, ByVal c As System.ComponentModel.ISynchronizeInvoke) As OutputType 
    Public Function InvokeEx(Of InputType, OutputType)(ByVal f As GenericLambdaFunctionWithParam(Of InputType, OutputType), ByVal input As InputType, ByVal c As System.ComponentModel.ISynchronizeInvoke) As OutputType 
     If c.InvokeRequired Then 
      Dim d As New InvokeLambdaFunctionCallback(Of InputType, OutputType)(AddressOf InvokeEx) 
      Return DirectCast(c.Invoke(d, New Object() {f, input, c}), OutputType) 
     Else 
      Return f(input) 
     End If 
    End Function 

    Public Delegate Sub GenericLambdaSubWithParam(Of InputType)(ByVal input As InputType) 
    Public Sub InvokeEx(Of InputType)(ByVal s As GenericLambdaSubWithParam(Of InputType), ByVal input As InputType, ByVal c As System.ComponentModel.ISynchronizeInvoke) 
     InvokeEx(Of InputType, Object)(Function(i As InputType) As Object 
              s(i) 
              Return Nothing 
             End Function, input, c) 
    End Sub 

    Public Delegate Sub GenericLambdaSub() 
    Public Sub InvokeEx(ByVal s As GenericLambdaSub, ByVal c As System.ComponentModel.ISynchronizeInvoke) 
     InvokeEx(Of Object, Object)(Function(i As Object) As Object 
             s() 
             Return Nothing 
            End Function, Nothing, c) 
    End Sub 

    Public Delegate Function GenericLambdaFunction(Of OutputType)() As OutputType 
    Public Function InvokeEx(Of OutputType)(ByVal f As GenericLambdaFunction(Of OutputType), ByVal c As System.ComponentModel.ISynchronizeInvoke) As OutputType 
     Return InvokeEx(Of Object, OutputType)(Function(i As Object) f(), Nothing, c) 
    End Function 
End Module 

Usage (eseguire questo in un BackgroundWorker):

InvokeEx(Sub(x As String) Me.Text = x, "foo", Me) 'set form title to foo 
    InvokeEx(AddressOf MsgBox, Me.Text, Me) 
    InvokeEx(Sub() Me.Text &= "!", "foo", Me) 'append "!" to form title 
    InvokeEx(AddressOf MsgBox, Me.Text, Me) 
    Dim s As String = InvokeEx(Function() Me.Text, Me) & "bar" 'get form title to backgorundworker thread 
    InvokeEx(AddressOf MsgBox, s, Me) 'display the string from backgroundworker thread 

Answer 4

ecco il codice equivalente VB per la risposta di Samuel che uso. avviso ho effettivamente 2 funzioni di estensione, ma devo ammettere che non so perché sono lì. Ho copiato la mia versione C# anni fa (forse da questo sito) e aveva entrambe le funzioni di estensione, ma per quale motivo, non capisco completamente. l'ho appena copiato e come usarlo, e a metà capisco tutto ciò che accade sotto le casse con queste complicate funzioni.

#Const System_ComponentModel = True 
#Const System_Drawing = False 

Option Compare Binary 
Option Explicit On 
Option Strict On 

Imports System.Collections 
Imports System.Runtime.CompilerServices ' for Extension() attribute 
Imports System.Text 
#If System_ComponentModel Then 
Imports System.ComponentModel 
#End If 
#If System_Drawing Then 
Imports System.Drawing 
#End If 

Public Module MyExtensions 

    ' other #Region blocks are removed. i use many in my Extensions 
    ' module/class. the below code is only the 2 relevant extension 
    ' for this 'SafeInvoke' functionality. but i use other regions 
    ' such as "String extensions" and "Numeric extensions". i use 
    ' the above System_ComponentModel and System_Drawing compiler 
    ' directives to include or exclude blocks of code that i want 
    ' to either include or exclude in a project, which allows me to 
    ' easily compare my code in one project with the same file in 
    ' other projects to syncronise new changes across projects. 
    ' you can scrap pretty much all the code above, 
    ' but i'm giving it here so you see it in the full context. 

    #Region "ISynchronizeInvoke extensions" 

    #If System_ComponentModel Then 

     <Extension()> 
     Public Function SafeInvoke(Of T As ISynchronizeInvoke, TResult)(isi As T, callFunction As Func(Of T, TResult)) As TResult 
      If (isi.InvokeRequired) Then 
       Dim result As IAsyncResult = isi.BeginInvoke(callFunction, New Object() {isi}) 
       Dim endresult As Object = isi.EndInvoke(result) 
       Return DirectCast(endresult, TResult) 
      Else 
       Return callFunction(isi) 
      End If 
     End Function 

     ''' <summary> 
     ''' This can be used in VB with: 
     ''' txtMyTextBox.SafeInvoke(Sub(d) d.Text = "This is my new Text value.") 
     ''' or: 
     ''' txtMyTextBox.SafeInvoke(Sub(d) d.Text = myTextStringVariable) 
     ''' </summary> 
     ''' <typeparam name="T"></typeparam> 
     ''' <param name="isi"></param> 
     ''' <param name="callFunction"></param> 
     ''' <remarks></remarks> 
     <Extension()> 
     Public Sub SafeInvoke(Of T As ISynchronizeInvoke)(isi As T, callFunction As Action(Of T)) 
      If isi.InvokeRequired Then 
       isi.BeginInvoke(callFunction, New Object() {isi}) 
      Else 
       callFunction(isi) 
      End If 
     End Sub 

    #End If 

    #End Region 

    ' other #Region blocks are removed from here too. 

End Module 

E il C# versione è:

#define System_ComponentModel 
#undef System_Drawing 

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 

#if System_ComponentModel 
using System.ComponentModel; 
#endif 
#if System_Drawing 
using System.Drawing; 
#endif 

namespace MyCompany.Extensions 
{ 
    static partial class MyExtensions 
    { 

     // other #Region blocks are removed. i use many in my Extensions 
     // module/class. the below code is only the 2 relevant extension 
     // for this 'SafeInvoke' functionality. but i use other regions 
     // such as "String extensions" and "Numeric extensions". i use 
     // the above System_ComponentModel and System_Drawing compiler 
     // directives to include or exclude blocks of code that i want 
     // to either include or exclude in a project, which allows me to 
     // easily compare my code in one project with the same file in 
     // other projects to syncronise new changes across projects. 
     // you can scrap pretty much all the code above, 
     // but i'm giving it here so you see it in the full context. 

     #region ISynchronizeInvoke extensions 
#if System_ComponentModel 

     public static TResult SafeInvoke<T, TResult>(this T isi, Func<T, TResult> callFunction) where T : ISynchronizeInvoke 
     { 
      if (isi.InvokeRequired) 
      { 
       IAsyncResult result = isi.BeginInvoke(callFunction, new object[] { isi }); 
       object endResult = isi.EndInvoke(result); return (TResult)endResult; 
      } 
      else 
       return callFunction(isi); 
     } 

     /// <summary> 
     /// This can be used in C# with: 
     /// txtMyTextBox.SafeInvoke(d => d.Text = "This is my new Text value."); 
     /// or: 
     /// txtMyTextBox.SafeInvoke(d => d.Text = myTextStringVariable); 
     /// </summary> 
     /// <typeparam name="T"></typeparam> 
     /// <param name="isi"></param> 
     /// <param name="callFunction"></param> 
     public static void SafeInvoke<T>(this T isi, Action<T> callFunction) where T : ISynchronizeInvoke 
     { 
      if (isi.InvokeRequired) isi.BeginInvoke(callFunction, new object[] { isi }); 
      else 
       callFunction(isi); 
     } 

#endif 
     #endregion 

     // other #Region blocks are removed from here too. 

    } // static class MyExtensions 

} // namespace 

Felice codifica!

Answer 5

Ora un giorno è facile Invoke per esempio dire che vogliamo invocare un Label (lblVal) per ottenere il valore di txtVal

lblVal.invoke((MethodInvoker)delegate{txtVal.Text = lblVal.Text;}); 

facile come questo: D