Aggiunta di supporto per il debug in un'attività personalizzata

Interfaccia IDTSBreakpointSite e BreakpointManager

Le attività creano destinazioni di punti di interruzione chiamando il metodo CreateBreakpointTarget di BreakpointManager, fornendo un ID integer e una stringa descrittiva come parametri. Quando l'attività raggiunge il punto del codice che contiene la destinazione del punto di interruzione, la valuta utilizzando il metodo IsBreakpointTargetEnabled per determinare se tale punto di interruzione è abilitato. Se true, l'attività invia una notifica al motore di runtime generando l'evento OnBreakpointHit.

L'interfaccia IDTSBreakpointSite definisce un singolo metodo, AcceptBreakpointManager, che viene chiamato dal motore di runtime durante la creazione di attività. Questo metodo fornisce come parametro l'oggetto BreakpointManager, che viene quindi utilizzato dall'attività per creare e gestire i propri punti di interruzione. Le attività devono archiviare l'oggetto BreakpointManager in locale per utilizzarlo durante i metodi Validate e Execute.

Nell'esempio di codice seguente viene illustrato come creare una destinazione di punti di interruzione tramite BreakpointManager. Viene chiamato il metodo OnBreakpointHit per generare l'evento.

public void AcceptBreakpointManager( BreakpointManager breakPointManager )
{
   //   Store the breakpoint manager locally.
   this.bpm  = breakPointManager;
}
public override DTSExecResult Execute( Connections connections,
  Variables variables, IDTSComponentEvents events,
  IDTSLogging log, DtsTransaction txn)
{
   //   Create a breakpoint.
   this.bpm.CreateBreakPointTarget( 1 , "A sample breakpoint target." );
...
   if( this.bpm.IsBreakpointTargetEnabled( 1 ) == true )
      events.OnBreakpointHit( this.bpm.GetBreakpointTarget( 1 ) );
}

Public Sub AcceptBreakpointManager(ByVal breakPointManager As BreakpointManager)

   ' Store the breakpoint manager locally.
   Me.bpm  = breakPointManager

End Sub

Public Overrides Function Execute(ByVal connections As Connections, _
  ByVal variables As Variables, ByVal events As IDTSComponentEvents, _
  ByVal log As IDTSLogging, ByVal txn As DtsTransaction) As DTSExecResult

   ' Create a breakpoint.
   Me.bpm.CreateBreakPointTarget(1 , "A sample breakpoint target.")

   If Me.bpm.IsBreakpointTargetEnabled(1) = True Then
      events.OnBreakpointHit(Me.bpm.GetBreakpointTarget(1))
   End If

End Function

Interfaccia IDTSSuspend

L'interfaccia IDTSSuspend definisce i metodi che vengono chiamati dal motore di runtime quando sospende o riprende l'esecuzione di un'attività. L'interfaccia IDTSSuspend viene implementata dall'interfaccia IDTSBreakpointSite e i relativi metodi Suspend e ResumeExecution vengono in genere sottoposti a override dall'attività personalizzata. Quando il motore di runtime riceve un evento OnBreakpointHit da un'attività, chiama il metodo Suspend di ogni attività in esecuzione, notificando la pausa alle attività. Quando il client riprende l'esecuzione, il motore di runtime chiama il metodo ResumeExecution delle attività sospese.

La sospensione e la ripresa dell'esecuzione di un'attività implica la sospensione e la ripresa del thread di esecuzione dell'attività. Nel codice gestito questo risultato si ottiene utilizzando la classe ManualResetEvent nello spazio dei nomi System.Threading di .NET Framework.

Nell'esempio di codice seguente vengono illustrate la sospensione e la ripresa dell'esecuzione di un'attività. Si noti che il metodo Execute è diverso rispetto all'esempio di codice precedente e che il thread di esecuzione è in pausa quando viene attivato il punto di interruzione.

private ManualResetEvent m_suspended = new ManualResetEvent( true );
private ManualResetEvent m_canExecute = new ManualResetEvent( true );
private int   m_suspendRequired = 0;
private int   m_debugMode = 0;

public override DTSExecResult Execute( Connections connections, Variables variables, IDTSComponentEvents events, IDTSLogging log, DtsTransaction txn)
{
   // While a task is not executing, it is suspended.  
   // Now that we are executing,
   // change to not suspended.
   ChangeEvent(m_suspended, false);
   
   // Check for a suspend before doing any work, 
   // in case the suspend and execute calls
   // were initiated at virtually the same time.
   CheckAndSuspend();
   CheckAndFireBreakpoint( componentEvents, 1);
}
private void CheckAndSuspend()
{
   // Loop until we can execute.  
   // The loop is required rather than a simple If
   // because there is a time between the return from WaitOne and the
   // reset that we might receive another Suspend call.  
   // Suspend() will see that we are suspended
   // and return.  So we need to rewait.
   while (!m_canExecute.WaitOne(0, false))
   {
      ChangeEvent(m_suspended, true);
      m_canExecute.WaitOne();
      ChangeEvent(m_suspended, false);
   }
}
private void CheckAndFireBreakpoint(IDTSComponentEvents events, int breakpointID)
{
   // If the breakpoint is enabled, fire it.
   if (m_debugMode != 0 &&    this.bpm.IsBreakpointTargetEnabled(breakpointID))
   {
      //   Enter a suspend mode before firing the breakpoint.  
      //   Firing the breakpoint will cause the runtime 
      //   to call Suspend on this task.  
      //   Because we are blocked on the breakpoint, 
      //   we are suspended.
      ChangeEvent(m_suspended, true);
      events.OnBreakpointHit(this.bpm.GetBreakpointTarget(breakpointID));
      ChangeEvent(m_suspended, false);
   }
   // Check for a suspension for two reasons: 
   //   1. If we are at a point where we could fire a breakpoint, 
   //      we are at a valid suspend point.  Even if we didn't hit a
   //      breakpoint, the runtime may have called suspend, 
   //      so check for it.     
   //   2. Between the return from OnBreakpointHit 
   //      and the reset of the event, it is possible to have
   //      received a suspend call from which we returned because 
   //      we were already suspended.  We need to be sure it is okay
   //      to continue executing now.
   CheckAndSuspend();
}
static void ChangeEvent(ManualResetEvent e, bool shouldSet)
{
   bool succeeded;
   if (shouldSet)
      succeeded = e.Set();
   else
      succeeded = e.Reset();

   if (!succeeded)
      throw new Exception("Synchronization object failed.");
            
}
public bool SuspendRequired
{
   get   {return m_suspendRequired != 0;}
   set
   {
      // This lock is also taken by Suspend().  
      // Because it is possible for the package to be
      // suspended and resumed in quick succession, 
      // this property might be set before
      // the actual Suspend() call.  
      // Without the lock, the Suspend() might reset the canExecute
      // event after we set it to abort the suspension.
      lock (this)
      {
         Interlocked.Exchange(ref m_suspendRequired, value ? 1 : 0);
         if (!value)
            ResumeExecution();
      }
   }
}
public void ResumeExecution()
{
   ChangeEvent( m_canExecute,true );
}
public void Suspend()
{
   // This lock is also taken by the set SuspendRequired method.  
   // It prevents this call from overriding an 
   // aborted suspension.  See comments in set SuspendRequired.
   lock (this)
   {
      // If a Suspend is required, do it.
      if (m_suspendRequired != 0)
         ChangeEvent(m_canExecute, false);
   }
   // We can't return from Suspend until the task is "suspended".
   // This can happen one of two ways: 
   // the m_suspended event occurs, indicating that the execute thread
   // has suspended, or the canExecute flag is set, 
   // indicating that a suspend is no longer required.
   WaitHandle [] suspendOperationComplete = {m_suspended, m_canExecute};
   WaitHandle.WaitAny(suspendOperationComplete);
}

Private m_suspended As ManualResetEvent = New ManualResetEvent(True)
Private m_canExecute As ManualResetEvent = New ManualResetEvent(True)
Private m_suspendRequired As Integer = 0
Private m_debugMode As Integer = 0

Public Overrides Function Execute(ByVal connections As Connections, _
ByVal variables As Variables, ByVal events As IDTSComponentEvents, _
ByVal log As IDTSLogging, ByVal txn As DtsTransaction) As DTSExecResult

   ' While a task is not executing it is suspended.  
   ' Now that we are executing,
   ' change to not suspended.
   ChangeEvent(m_suspended, False)

   ' Check for a suspend before doing any work, 
   ' in case the suspend and execute calls
   ' were initiated at virtually the same time.
   CheckAndSuspend()
   CheckAndFireBreakpoint(componentEvents, 1)

End Function

Private Sub CheckAndSuspend()

   ' Loop until we can execute.  
   ' The loop is required rather than a simple if
   ' because there is a time between the return from WaitOne and the
   ' reset that we might receive another Suspend call.  
   ' Suspend() will see that we are suspended
   ' and return.  So we need to rewait.
   Do While Not m_canExecute.WaitOne(0, False)
              ChangeEvent(m_suspended, True)
              m_canExecute.WaitOne()
              ChangeEvent(m_suspended, False)
   Loop

End Sub

Private Sub CheckAndFireBreakpoint(ByVal events As IDTSComponentEvents, _
ByVal breakpointID As Integer)

   ' If the breakpoint is enabled, fire it.
   If m_debugMode <> 0 AndAlso Me.bpm.IsBreakpointTargetEnabled(breakpointID) Then
              '   Enter a suspend mode before firing the breakpoint.  
              '   Firing the breakpoint will cause the runtime 
              '   to call Suspend on this task.  
              '   Because we are blocked on the breakpoint, 
              '   we are suspended.
              ChangeEvent(m_suspended, True)
              events.OnBreakpointHit(Me.bpm.GetBreakpointTarget(breakpointID))
              ChangeEvent(m_suspended, False)
   End If

   ' Check for a suspension for two reasons: 
   '   1. If we are at a point where we could fire a breakpoint, 
   '         we are at a valid suspend point.  Even if we didn't hit a
   '         breakpoint, the runtime may have called suspend, 
   '         so check for it.   
   '   2. Between the return from OnBreakpointHit 
   '         and the reset of the event, it is possible to have
   '         received a suspend call from which we returned because 
   '         we were already suspended.  We need to be sure it is okay
   '         to continue executing now.
   CheckAndSuspend()

End Sub

Shared Sub ChangeEvent(ByVal e As ManualResetEvent, ByVal shouldSet As Boolean)

   Dim succeeded As Boolean
   If shouldSet Then
              succeeded = e.Set()
   Else
              succeeded = e.Reset()
   End If

   If (Not succeeded) Then
              Throw New Exception("Synchronization object failed.")
   End If
 
End Sub

Public Property SuspendRequired() As Boolean
   Get
               Return m_suspendRequired <> 0
  End Get
  Set
    ' This lock is also taken by Suspend().  
     '   Because it is possible for the package to be
     '   suspended and resumed in quick succession, 
     '   this property might be set before
     '   the actual Suspend() call.  
     '   Without the lock, the Suspend() might reset the canExecute
     '   event after we set it to abort the suspension.
              SyncLock Me
                         Interlocked.Exchange(m_suspendRequired,IIf(Value, 1, 0))
                         If (Not Value) Then
                                    ResumeExecution()
                         End If
              End SyncLock
   End Set
End Property

Public Sub ResumeExecution()
   ChangeEvent(m_canExecute,True)
End Sub

Public Sub Suspend()

   ' This lock is also taken by the set SuspendRequired method.  
   ' It prevents this call from overriding an 
   ' aborted suspension.  See comments in set SuspendRequired.
   SyncLock Me
   ' If a Suspend is required, do it.
              If m_suspendRequired <> 0 Then
                         ChangeEvent(m_canExecute, False)
              End If
   End SyncLock
   ' We can't return from Suspend until the task is "suspended".
   ' This can happen one of two ways: 
   ' the m_suspended event occurs, indicating that the execute thread
   ' has suspended, or the canExecute flag is set, 
   ' indicating that a suspend is no longer required.
   Dim suspendOperationComplete As WaitHandle() = {m_suspended, m_canExecute}
   WaitHandle.WaitAny(suspendOperationComplete)

End Sub

Vedere anche

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