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Asynchronous Child Process postFunc Handler and the CIW

Palenzuela18

Hi everyone. Still kind of a beginner in this SKILL thing. I need to invoke a process asynchronously and run a cutom function when it ends. Below I add an equivalent simple script that simplifies my situation. As you can see, I'm using the "ipcBeginProcess(...)" function to invoke a simple Python command, specifying as an argument the tsu_postFunc handler. From my limited understanding (Cadence Interprocess Communication SKILL Reference IC23.1), the function specified as tsu_postFunc is invoked when the child process ends it's execution. I have two questions about it.

----------------------------------------------------------------------------------

procedure( launchAsynchronousCMD( cmd )
   let( (cid)
      ; Launch process
         cid = ipcBeginProcess(
         cmd ;; command
         "" ;; locally
         nil ;; data handler function
         nil ;; error handler function
         'pFuncHandler ;; post func
          ""
      )
      cid
   )
)


defun( pFuncHandler ( cid exitStatus )
   ipcSleep(1)
   printf( "** FINISHED ** [%A - %A]: %A\n" cid cid->processPid exitStatus )
)


cid = launchAsynchronousCMD("python -c 'import time; time.sleep(5)'")

----------------------------------------------------------------------------------


1. If I do not add the call to ipcSleep(1), why doesn't the finish message get printed in the CIW until I execute another SKILL command?

2. If I intentionally add an error to the code of tsu_postFunc, why doesn't the error get printed in the CIW? How can I get it printed?

Details about the under the hood explanation are more than welcome. Thanks before hand.

Parents

  • Answers to your questions:

    1. This should not be necessary - and when I tried it, I don't need the ipcSleep - I get the message as soon as the process has finished. It might not get executed immediately because it's done when the SKILL top-level is available (so if there's something actively running in Virtuoso, it will happen once that's finished as there's only a single thread), but in general the delay will not make a difference.
    2. See Errors in an IPC done handler or postfunction are trapped but not displayed

    Andrew

  • in reply to Andrew Beckett

    Thanks Andrew, really appreciate the quick and clear response.

    About the linked resource, it perfectly solves my problem.

    About the top-level topic, I have stumbled with this term more than a couple times in SKILL documentation. The only usefull resource I found was the little said on the "Cadence SKILL User Guide". Do you know where can I get a clear understanding of this concept?

  • in reply to Palenzuela18

    There's not really that much that covers this (other than the documentation for the SKILL function toplevel but even that doesn't really). In essence, there's a REPL (Read-Eval-Print-Loop) that is the interface to the SKILL engine; SKILL itself is single-threaded, and so any input from the CIW, from bindkeys, from menu callbacks, form interactions, IPC callbacks etc feed into the the top-level SKILL engine. If Virtuoso is busy (e.g. executing some lengthy SKILL code or something at the C++ level) the top-level is blocked and so execution of any SKILL code (which might be enqueued into it to) happens as soon as the blocking function returns and the top-level becomes available again. Hopefully that's a simple enough conceptional description of how it works!

    Andrew 

Reply
  • in reply to Palenzuela18

    There's not really that much that covers this (other than the documentation for the SKILL function toplevel but even that doesn't really). In essence, there's a REPL (Read-Eval-Print-Loop) that is the interface to the SKILL engine; SKILL itself is single-threaded, and so any input from the CIW, from bindkeys, from menu callbacks, form interactions, IPC callbacks etc feed into the the top-level SKILL engine. If Virtuoso is busy (e.g. executing some lengthy SKILL code or something at the C++ level) the top-level is blocked and so execution of any SKILL code (which might be enqueued into it to) happens as soon as the blocking function returns and the top-level becomes available again. Hopefully that's a simple enough conceptional description of how it works!

    Andrew 

Children

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