[R-pkg-devel] New test in R-devel causes existing packages to fail: "Error: connections left open"

[Gábor Csárdi]

You could just create a function to close the connection and then
people could call it at the end of their test suites.

Gabor
On Sun, Aug 19, 2018 at 6:22 PM David B. Dahl <dahl using stat.byu.edu> wrote:
>
> In preparing to submit an update of my package to CRAN, I found that
> R-devel has a new test regarding "connects left open" that my packages
> fail.  The new test appears to have been committed by Uwe Ligges in
> revisions 74959 and 74964 on 2018-07-14 and 2018-07-15, respectively.
> The commit message says, "check after each example whether open
> connections exist, indicating e.g. file connections were left open or
> parallel clusters still running."
>
> I am hoping for advice on how to pass "R CMD check --as-cran".  Or,
> perhaps my situation will prompt a change to the test or, at least,
> having it result in a warning instead of an error.
>
> Below I describe the situation.  My rscala package allows developers
> to write R packages based on Scala (much like rJava and Rcpp for Java
> and C++, respectively).  Scala runs as a separate process and
> interprocess communication is implemented using socket connections.
>
> Suppose a package using rscala has functions that call Scala code.
> (Such packages are 'bamboo', 'sdols', and 'shallot' on CRAN.)  The
> first time a user executes an R function calling down into Scala, a
> socket connect between Scala and R is established.  For the sake of
> low latency, after the call to the function ends, the connection stays
> open until the package is unloaded or the R session ends.  But, this
> approach runs afoul of the new test mentioned above that appears to be
> designed to catch connections that are *accidentally* left open.
>
> I definitely do not want to users of my packages 'bamboo', 'sdols',
> and 'shallot' to have to think about managing connection between Scala
> and R.  That's an implementation detail and uing the package should be
> transparent for the user (who doesn't care about the implementation
> details).
>
> On my end, I see two solutions:  1. I could try to reengineer my
> approach --- establishing a new connection for every single call into
> Scala --- although I am loath to do anything to increase the latency,
> or 2. I could wrap all the examples in \donttest so that CRAN checks
> are passed.
>
> Or, again, perhaps my situation will prompt a reevaluation of the
> test.  Perhaps it could result in a warning (instead of an error) and
> the CRAN maintainers would accept packages with such a warning.
>
> Any advise?  Thanks a lot!
>
> -- David
>
> ______________________________________________
> R-package-devel using r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-package-devel