dbConnect(check_interrupt = TRUE) broken?

[krlmlr]

The interrupt seems to be caught by select() on the socket, not by Rcpp::checkUserInterrupt() as intended by the code. This leads to an error message Rcpp::exception: select() failed with error code 4 (where 4 means EINTR), and the subsequent cleanup (in an overarching try-catch?) still waits for the query to complete.

Same on macOS and Linux. Not tested on Windows.

session <- callr::r_session$new()

session$run(function() {
  library(RPostgres)
  .GlobalEnv$conn <- dbConnect(Postgres(), check_interrupts = TRUE)
  invisible()
})
#> NULL
session$call(function() {
  tryCatch(
    print(dbGetQuery(.GlobalEnv$conn, "SELECT pg_sleep(2)")),
    error = identity
  )
})

session$poll_process(100)
#> [1] "timeout"
session$read()
#> NULL
session$interrupt()
#> [1] TRUE
# Should take much less than 1.9 seconds
system.time(print(session$poll_process(2000)))
#> [1] "ready"
#>    user  system elapsed 
#>   0.000   0.001   1.904
# Should return a proper error message
session$read()
#> $code
#> [1] 200
#> 
#> $message
#> [1] "done callr-rs-result-f8d028852a34"
#> 
#> $result
#> <Rcpp::exception: select() failed with error code 4>
#> 
#> $stdout
#> [1] ""
#> 
#> $stderr
#> [1] ""
#> 
#> $error
#> NULL
#> 
#> attr(,"class")
#> [1] "callr_session_result"

^{Created on 2021-09-19 by the reprex package (v2.0.1)}

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