Retry a function when it fails — retry • garnish

Decorator that calls a function again until it succeeds or a stop condition condition is met, sleeping between attempts. Port of Python's tenacity.

Usage

retry(
  f,
  stop = stop_never(),
  wait = wait_none(),
  retry = retry_all(),
  before_sleep = before_sleep_none(),
  after_sleep = after_sleep_none(),
  reraise = FALSE,
  retry_error_callback = NULL
)

Arguments

f: The function to decorate. Usually supplied by %@% rather than directly.
stop: A stop condition, e.g. stop_after_attempt(). Defaults to never stopping.
wait: A wait strategy. Defaults to no waiting.
retry: A retry condition. Defaults to retrying every error.
before_sleep, after_sleep: Hooks run before and after each sleep, see before_sleep_log() and after_sleep_log().
reraise: If TRUE, re-throw the last error when stop fires instead of throwing a retry_error.
retry_error_callback: Optional function called with the final state when stop fires. Its return value is returned instead of throwing. The state is a list with attempt, wait, elapsed, error and value.

Value

A decorator. The decorated function returns the first acceptable result, or signals a retry_error condition (with $attempt, $error and $value) once stop fires.

Details

Call retry(stop, wait, retry, before_sleep, after_sleep, reraise, retry_error_callback) to build a decorator, then apply it with %@% or by calling it on a function.

Examples

n <- 0
flaky <- function() {
  n <<- n + 1
  if (n < 3) stop("not yet")
  n
}
retry(stop = stop_after_attempt(5))(flaky)()
#> [1] 3

# Back off exponentially between attempts
f <- retry(stop = stop_after_attempt(3), wait = wait_exp(min = 0.1)) %@% function() 1
f()
#> [1] 1