Throw error if timeout < 1ms.

Closes #175

NEWS.md

@@ -6,6 +6,8 @@
   and we can't guess the type from the extension, we now assume that it's 
   `application/octet-stream` (#181).
 
+* Throw error if `timeout()` is less than 1 ms (#175).
+
 # httr 0.6.0
 
 ## New features

R/timeout.r

@@ -1,6 +1,7 @@
 #' Set maximum request time.
 #'
 #' @param seconds number of seconds to wait for a response until giving up.
+#'   Can not be less than 1 ms.
 #' @family config
 #' @export
 #' @examples
@@ -9,5 +10,9 @@
 #' GET("http://httpbin.org/delay/1", timeout(2))
 #' }
 timeout <- function(seconds) {
+  if (seconds < 0.001) {
+    stop("Timeout cannot be less than 1 ms", call. = FALSE)
+  }
+
   config(timeout.ms = seconds * 1000)
 }