Fix for close ShinySession on on.exit

[galachad]

The onSessionEnd is probably triggered by later loop and is never trigger on SIGINT signal. There is a difference between interactive and not interactive R process. In not interactive R process after global onStop callback, the R process is terminated immediately.

The minimal example:

library(shiny)

ui <- fluidPage(

)

server <- function(input, output, session) {
  onSessionEnded(function() {
    print("close ShinySession session")
  })
}

onStop(function() {
  # Custom code that was used before this PR.
  lapply(shiny:::appsByToken$keys(), function(session) {
    session <- shiny:::appsByToken$get(session)
    if (isFALSE(session$closed)) session$wsClosed()
  })
})

shinyApp(ui, server)

The gif example shows the difference.

If I can do some more in this case or you need more clarification, please let me know.

[wch]

I think that #2743 may have the same root cause as the issue you're describing.

In your command-line script, if, instead of using this PR, you add this after the call to runApp(), does the onSessionEnded callback execute properly?

for (i in 1:10) later::run_now()

[galachad]

@wch I totally agree, it's even better to trigger later loop on stop callback. It's not really solved #2743 issue because the second runApp is executed before later loop. In my opinion it will be good to add run_now at the beginning of runApp.

runApp(app)
later::run_now()
runApp(app)

[galachad]

I was to fast, I check twice and it does not execute callback properly.

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