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Author: Stefan Fleck

R/Cache.R

@@ -301,6 +301,13 @@ Cache <- R6::R6Class(
     #'   a storage key must be supplied manually in `cache$push()`. If a new
     #'   object is added with the same key as an existing object, the existing
     #'   object will be overwritten without warning.
+    #'
+    #'   *Note:*
+    #'   If hashfun is something that generates a unique ID instead of a hash,
+    #'   it is recommended to use a lexically sortable unique ID (such as ulid).
+    #'   This ensures that `$prune()` and co will delete objects in order of
+    #'   their creation at sub-second accuracy. This is only an issue on
+    #'   file-systems with low precission timestamp such as ext3 or FAT.
     hashfun = function(fun){
       if (missing(fun)){
         res <- get(".hashfun", envir = private)

tests/testthat/test_Cache.R

@@ -4,8 +4,6 @@ context("Cache")
 # generate lexically sortable ids. For equal timestamp, Cache$files is sorted
 # by id, so that the tests do not fail on file systems with low-accuracy
 # timestamps
-
-
 .id_cache <- new.env()
 assign("id", 0L, .id_cache)
 ascending_id <- function(){