R.utils (version 1.12.0)

evalWithTimeout: Evaluate an R expression and interrupts it if it takes too long

Description

Evaluate an R expression and interrupts it if it takes too long.

Usage

evalWithTimeout(..., envir=parent.frame(), timeout, cpu=timeout, elapsed=timeout, onTimeout=c("error", "warning", "silent"))

Arguments

...

The R expression to be evaluated as passed to eval().

envir

The environment in which the expression should be evaluated.

timeout, cpu, elapsed

A numeric specifying the maximum number of seconds the expression is allowed to run before being interrupted by the timeout. The cpu and elapsed arguments can b

onTimeout

A character specifying what action to take if a timeout event occurs.

Value

• Returns the results of the expression evaluated. If timed out, NULL is returned if onTimeout was "warning" or "silent". If "error" a TimeoutException is thrown.

Non-supported cases

It is not possible to interrupt/break out of a "readline" prompt (e.g. readline() and readLines()) using timeouts; the timeout exception will not be thrown until after the user completes the prompt (i.e. after pressing ENTER).

References

[1] R help thread 'Time out for a R Function' on 2010-12-06. http://www.mail-archive.com/[e-mail]/msg119344.html

See Also

setTimeLimit()

Examples

# - - - - - - - - - - - - - - - - - - - - - - - - -
# Function that takes "a long" time to run
# - - - - - - - - - - - - - - - - - - - - - - - - -
foo <- function() {
  print("Tic");
  for (kk in 1:100) {
    print(kk);
    Sys.sleep(0.1);
  }
  print("Tac");
}


# - - - - - - - - - - - - - - - - - - - - - - - - -
# Evaluate code, if it takes too long, generate
# a timeout by throwing a TimeoutException.
# - - - - - - - - - - - - - - - - - - - - - - - - -
res <- NULL;
tryCatch({
  res <- evalWithTimeout({
    foo();
  }, timeout=1.08);
}, TimeoutException=function(ex) {
  cat("Timeout. Skipping.
");
})


# - - - - - - - - - - - - - - - - - - - - - - - - -
# Evaluate code, if it takes too long, generate
# a timeout returning NULL and generate a warning.
# - - - - - - - - - - - - - - - - - - - - - - - - -
res <- evalWithTimeout({
  foo();
}, timeout=1.08, onTimeout="warning");


# - - - - - - - - - - - - - - - - - - - - - - - - -
# Evaluate code, if it takes too long, generate
# a timeout, and return silently NULL.
# - - - - - - - - - - - - - - - - - - - - - - - - -
res <- evalWithTimeout({
  foo();
}, timeout=1.08, onTimeout="silent");