RETRY options to ignore statuses and use try

R/retry.R

@@ -16,7 +16,13 @@
 #'   \code{pause_cap} seconds.
 #' @param quiet If \code{FALSE}, will print a message displaying how long
 #'   until the next request.
-#' @return The last response. Note that if the request doesn't succeed after
+#' @param use_try If \code{TRUE}, will wrap the request execution in a call to
+#'   \code{\link[base]{try}()} in order to catch lower level errors in the
+#'   request.
+#' @param safe_statuses Integer vector of status codes that should be considered
+#'   safe and not cause a retry.
+#' @return The last response or, if \code{use_try} was \code{TRUE}, an invisible
+#'   object of class \code{"try-error"}. Note that if the request doesn't succeed after
 #'   \code{times} times this will be a failed request, i.e. you still need
 #'   to use \code{\link{stop_for_status}()}.
 #' @export
@@ -25,29 +31,50 @@
 #' RETRY("GET", "http://httpbin.org/status/200")
 #' # Never succeeds
 #' RETRY("GET", "http://httpbin.org/status/500")
+#' # Returns immediately with a 404 response
+#' RETRY("GET", "http://httpbin.org/status/404", safe_statuses = 400L)
 RETRY <- function(verb, url = NULL, config = list(), ...,
                   body = NULL, encode = c("multipart", "form", "json", "raw"),
                   times = 3, pause_base = 1, pause_cap = 60,
-                  handle = NULL, quiet = FALSE) {
+                  handle = NULL, quiet = FALSE, use_try = FALSE, safe_statuses = integer()) {
   stopifnot(is.numeric(times), length(times) == 1L)
   stopifnot(is.numeric(pause_base), length(pause_base) == 1L)
   stopifnot(is.numeric(pause_cap), length(pause_cap) == 1L)
+  stopifnot(is.logical(use_try), length(use_try) == 1L, !is.na(use_try))
+  stopifnot(is.integer(safe_statuses))
 
   hu <- handle_url(handle, url, ...)
   req <- request_build(verb, hu$url, body_config(body, match.arg(encode)), config, ...)
-  resp <- request_perform(req, hu$handle$handle)
+  resp <- if (use_try) {
+    try(request_perform(req, hu$handle$handle))
+  } else {
+    request_perform(req, hu$handle$handle)
+  }
 
   i <- 1
-  while (i < times && http_error(resp)) {
-    backoff_full_jitter(i, status_code(resp), pause_base, pause_cap, quiet = quiet)
+  while (i < times && should_retry(resp, safe_statuses)) {
+    status = if ("try-error" %in% class(resp)) {
+      attr(resp, "condition")$message
+    } else {
+      status_code(resp)
+    }
+    backoff_full_jitter(i, status, pause_base, pause_cap, quiet = quiet)
 
     i <- i + 1
-    resp <- request_perform(req, hu$handle$handle)
+    resp <- if (use_try) {
+      try(request_perform(req, hu$handle$handle))
+    } else {
+      request_perform(req, hu$handle$handle)
+    }
   }
 
   resp
 }
 
+should_retry <- function(resp, safe_statuses) {
+  "try-error" %in% class(resp) || (!status_code(resp) %in% safe_statuses && http_error(resp))
+}
+
 backoff_full_jitter <- function(i, status, pause_base = 1, pause_cap = 60, quiet = FALSE) {
   length <- ceiling(stats::runif(1, max = min(pause_cap, pause_base * (2 ^ i))))
   if (!quiet) {