ScheduleSolution, ExpireSolution and external events

Dear All,

EDIT: Added a non-Excel dependent version to the second post…

I am trying to create a (VB) component that issues a solution recalculation on a change of a referenced Excel workbook (cells) using Excel interop services. I have attached a model with a minimum set of components and lines of code to demonstrate the issue I am struggling with.

Imports Microsoft.Office.Interop

Private Sub RunScript(ByVal P As System.Object, ByRef B As Object)
   RhinoApp.WriteLine("--- Script staring...")
   app = System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application")
   wb = app.Workbooks.Open(P)
   B = "Now"
End Sub

Private app As Excel.Application
WithEvents Private wb As Excel.Workbook
Private counter As int32

Private Sub SheetChange(ByVal Sh As Object, ByVal Target As Object) Handles wb.SheetChange
  counter = counter + 1
  RhinoApp.WriteLine("Workbook changed " & counter & " times, issuing ExpireSolution in 5 secs...")
  Component.OnPingDocument.ScheduleSolution(5000, AddressOf Schedule_CB)
End Sub

Private Sub Schedule_CB()
  RhinoApp.WriteLine("Recalculating, SolutionState: " & Component.OnPingDocument.SolutionState)
  Component.ExpireSolution(True)
End Sub

So far:

  • The event handler works fine. Actually, if I put ExpireSolution there, the model performs pretty well and does its job.
  • However, of course, in that case if the next change event occurs earlier than the solution finishes, it will throw the object expired during a solution exception (which is definitely reasonable)
  • As I read I should use ScheduleSolution to handle such cases, and issue the ExpireSolution from its callback. I tried to implement it, but ended up having an endless loop of recalculations at the first time the event occurs.
  • Callback reached fine, timing is ok. Examining SolutionState does not help, it switches from 2 (PostProcess) to 0 (PreProcess) but never reaches 1 (Process).
  • It seems to me it is not an issue of instantly rescheduling a solution (as there is no delay), but the callback function getting called over and over again.

image

To reproduce using the attached model:

  • Probably need to reference the ‘Microsoft.Office.Interop.Excel.dll’ library on your system. Look for folders in the Global Assembly Cache (GAC) tree of Windows. Different Office versions (i.e. using 14 instead of 15) should work fine.
  • Create and save an empty Excel workbook to a location of your choice (of course you can use an existing one)
  • Modify the ‘Path/File’ container in the model accordingly
  • Make a change in any sheets of the Excel workbook
  • If all goes right (haha), you will end up with a (warning!) crashed Rhino.

(Technical details: Rhino 6.16.19190.7001, 07/09/2019, Grasshopper 1.0.0007, Windows 10, Office 2016)

Any help is truly appreciated, thank you!

Marton

ScheduleSolutionExcel.gh (4.3 KB)

Ok, to make testing/debugging easier I have created an alternate version of the model using the GH_FileWatcher class so it no longer depends on some exotic library references, should run on any GH without problems.

Set Path/File on any file on your file system and if the file is written to the disk (i.e. saved), the event will fire. The issue remains the same.

Private Sub RunScript(ByVal P As System.Object, ByRef B As Object) 
  RhinoApp.WriteLine("--- Script starting...")
  If Not watchers.Contains(P) Then
    GH_FileWatcher.CreateFileWatcher(P, GH_FileWatcherEvents.Changed, AddressOf FileChanged)
    watchers.add(P)
  End If
  B = "Now"
End Sub

Private watchers As New ArrayList
Private counter As int32

Private Sub FileChanged(filePath As String)
  counter = counter + 1
  RhinoApp.WriteLine("File changed " & counter & " times, issuing ExpireSolution in 5 secs...")
  Component.OnPingDocument.ScheduleSolution(5000, AddressOf Schedule_CB)
End Sub

Private Sub Schedule_CB()
  RhinoApp.WriteLine("Recalculating, SolutionState: " & component.OnPingDocument.SolutionState)
  Component.ExpireSolution(True)
End Sub

Thanks again,

Marton

ScheduleSolutionFileChanged.gh (4.1 KB)

Ok, I found the solution in the old forum topic Time delay when Component ExpireSolution()

@DavidRutten

A schedule will already start a new solution, so you don’t have to do so from within the callback. I’m not sure but that may trigger some weird kind of recursive thing which floods the callstack.

Inside your callback, use Cluster.ExpireSolution(false);

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