#' Amazon Web Services S3 Cache
#' Amazon Web Services S3 backed cache, for remote caching.
#'
#' @examples
#'
#' \dontrun{
#' # Set AWS credentials.
#' Sys.setenv("AWS_ACCESS_KEY_ID" = "<access key>",
#' "AWS_SECRET_ACCESS_KEY" = "<access secret>")
#'
#' # Set up a unique bucket name.
#' s3 <- cache_s3("unique-bucket-name")
#' mem_runif <- memoise(runif, cache = s3)
#' }
#'
#'
#' @param cache_name Bucket name for storing cache files.
#' @param compress Argument passed to \code{saveRDS}. One of FALSE, "gzip",
#' "bzip2" or "xz". Default: FALSE.
#' @inheritParams cache_memory
#' @export
cache_s3 <- function(cache_name, algo = "sha512", compress = FALSE) {
if (!(requireNamespace("digest"))) { stop("Package `digest` must be installed for `cache_s3()`.") } # nocov
if (!(requireNamespace("aws.s3"))) { stop("Package `aws.s3` must be installed for `cache_s3()`.") } # nocov
if (!(aws.s3::bucket_exists(cache_name))) {
aws.s3::put_bucket(cache_name) # nocov
}
path <- tempfile("memoise-")
dir.create(path)
cache_reset <- function() {
keys <- cache_keys()
lapply(keys, aws.s3::delete_bucket, bucket = cache_name)
}
cache_set <- function(key, value) {
temp_file <- file.path(path, key)
on.exit(unlink(temp_file))
saveRDS(value, file = temp_file, compress = compress)
aws.s3::put_object(temp_file, object = key, bucket = cache_name)
}
cache_get <- function(key) {
temp_file <- file.path(path, key)
httr::with_config(httr::write_disk(temp_file, overwrite = TRUE), {
aws.s3::get_object(object = key, bucket = cache_name)
})
readRDS(temp_file)
}
cache_has_key <- function(key) {
suppressMessages(aws.s3::head_object(object = key, bucket = cache_name))
}
cache_drop_key <- function(key) {
aws.s3::delete_bucket(key, bucket = cache_name)
}
cache_keys <- function() {
items <- lapply(aws.s3::get_bucket(bucket = cache_name), `[[`, "Key")
as.character(unlist(Filter(Negate(is.null), items)))
}
list(
digest = function(...) digest::digest(..., algo = algo),
reset = cache_reset,
set = cache_set,
get = cache_get,
has_key = cache_has_key,
drop_key = cache_drop_key,
keys = cache_keys
)
}
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