Add Azure storage option

DESCRIPTION

@@ -25,7 +25,11 @@ Authors@R:
       person(given = "Mark",
              family = "Edmondson",
              role = "ctb",
-             email = "[email protected]"))
+             email = "[email protected]"),
+      person(given = "Hong",
+             family = "Ooi",
+             role = "ctb",
+             email = "[email protected]"))
 Description: Cache the results of a function so that when you
     call it again with the same arguments it returns the pre-computed
     value.
@@ -41,6 +45,8 @@ Suggests:
     covr,
     googleAuthR,
     googleCloudStorageR,
+    AzureStor (>= 3.0.0),
+    AzureAuth,
     httr,
     testthat
 Remotes:

NAMESPACE

@@ -1,6 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
 S3method(print,memoised)
+export(cache_azure)
 export(cache_filesystem)
 export(cache_gcs)
 export(cache_memory)

R/cache_azure.R

@@ -0,0 +1,104 @@
+#' Azure Storage Cache
+#'
+#' Azure Storage backed cache, for remote caching. File, blob and ADLSgen2 storage are all supported.
+#'
+#' @examples
+#'
+#' \dontrun{
+#' library(AzureStor)
+#'
+#' # use Azure blob storage for the cache
+#' stor <- storage_endpoint("https://blob.accountname.core.windows.net", key="storage-key")
+#' azcache <- cache_azure("cache_container", stor)
+#' mem_runif <- memoise(runif, cache = azcache)
+#'
+#'
+#' # you can also pass the endpoint URL and key to cache_azure:
+#' azcache <- cache_azure("cache_container", "https://blob.accountname.core.windows.net",
+#'                        key = "storage-key")
+#'
+#' # a better alternative to a master key: OAuth 2.0 authentication via AAD
+#' token <- AzureAuth::get_azure_token(
+#'   "https://storage.azure.com",
+#'   tenant = "mytenant",
+#'   app = "app_id"
+#' )
+#' azcache <- cache_azure("cache_container", "https://blob.accountname.core.windows.net",
+#'                        token = token)
+#' }
+#'
+#' @param cache_name Name of the storage container for storing cache files.
+#' @param endpoint The storage account endpoint for the cache. This should be an object of class \code{AzureStor::storage_endpoint}, or inheriting from it. Alternatively, you can provide the endpoint URL as a string, and pass any authentication arguments in `...`.
+#' @param compress Argument passed to \code{saveRDS}. One of FALSE, "gzip",
+#' "bzip2" or "xz". Default: FALSE.
+#' @param ... Further arguments that will be passed to \code{AzureStor::storage_endpoint}, if \code{endpoint} is a URL.
+#' @export
+cache_azure <- function(cache_name, endpoint, compress = FALSE, ...) {
+  if(!requireNamespace("AzureStor")) { stop("Package `AzureStor` must be installed for `cache_azure()`.") } # nocov
+
+  if(is.character(endpoint)) {
+    endpoint <- AzureStor::storage_endpoint(endpoint, ...)
+  } else if(!inherits(endpoint, "storage_endpoint")) {
+    stop("Must provide either the URL of a storage account endpoint, or a `storage_endpoint` object")
+  }
+
+  path <- tempfile("memoise-")
+  dir.create(path)
+
+  # create container if it doesn't exist
+  try(AzureStor::create_storage_container(endpoint, cache_name), silent = TRUE)
+  cache <- AzureStor::storage_container(endpoint, cache_name)
+
+  cache_reset <- function() {
+    keys <- cache_keys()
+    lapply(keys, function(key) {
+       AzureStor::delete_storage_file(cache, key, confirm = FALSE)
+    })
+  }
+
+  cache_set <- function(key, value) {
+    rds <- file.path(path, key)
+    saveRDS(value, rds, compress = compress)
+    opts <- options(azure_storage_progress_bar = FALSE)
+    on.exit({
+      unlink(rds)
+      options(opts)
+    })
+    AzureStor::storage_upload(cache, rds, key)
+  }
+
+  cache_get <- function(key) {
+    rds <- file.path(path, key)
+    opts <- options(azure_storage_progress_bar = FALSE)
+    on.exit({
+      unlink(rds)
+      options(opts)
+    })
+    res <- try(AzureStor::storage_download(cache, key, rds, overwrite = TRUE), silent = TRUE)
+    if(inherits(res, "try-error")) {
+      return(cachem::key_missing())
+    }
+    readRDS(rds)
+  }
+
+  cache_has_key <- function(key) {
+    key %in% cache_keys()
+  }
+
+  cache_drop_key <- function(key) {
+    AzureStor::delete_storage_file(cache, key, confirm = FALSE)
+  }
+
+  cache_keys <- function() {
+    AzureStor::list_storage_files(cache, info = "name")
+  }
+
+  list(
+    reset = cache_reset,
+    set = cache_set,
+    get = cache_get,
+    exists = cache_has_key,
+    remove = cache_drop_key,
+    keys = cache_keys
+  )
+}

R/cache_filesystem.R

@@ -21,6 +21,12 @@
 #'
 #' mem_runif <- memoise(runif, cache = gd)
 #'
+#' # Use with OneDrive (on Windows)
+#'
+#' od <- cache_filesystem("~/../OneDrive")
+#'
+#' mem_runif <- memoise(runif, cache = od)
+#'
 #' }
 #'
 #' @export

tests/testthat/helper.R

@@ -23,3 +23,14 @@ skip_on_travis_pr <- function() {
 
   invisible(TRUE)
 }
+
+skip_without_azure_credentials <- function() {
+  storage_url <- Sys.getenv("AZ_TEST_STORAGE_MEMOISE_URL")
+  storage_key <- Sys.getenv("AZ_TEST_STORAGE_MEMOISE_KEY")
+
+  if (storage_url == "" || storage_key == "") {
+    testthat::skip("No Azure storage credentials")
+  } else {
+    invisible(TRUE)
+  }
+}

tests/testthat/test-azure.R

@@ -0,0 +1,41 @@
+context("azure storage")
+
+skip_on_cran()
+skip_on_travis_pr()
+skip_without_azure_credentials()
+
+storage_url <- Sys.getenv("AZ_TEST_STORAGE_MEMOISE_URL")
+storage_key <- Sys.getenv("AZ_TEST_STORAGE_MEMOISE_KEY")
+
+bl_endp <- AzureStor::storage_endpoint(storage_url, key=storage_key)
+cache_name <- paste0(sample(letters, 20, TRUE), collapse = "")
+
+test_that("using an Azure storage cache works", {
+
+  azcache <- cache_azure(cache_name, bl_endp)
+  i <- 0
+  fn <- function() { i <<- i + 1; i }
+  fnm <- memoise(fn, cache = azcache)
+  on.exit(forget(fnm))
+
+  expect_equal(fn(), 1)
+  expect_equal(fn(), 2)
+  expect_equal(fnm(), 3)
+  expect_equal(fnm(), 3)
+  expect_equal(fn(), 4)
+  expect_equal(fnm(), 3)
+
+  expect_false(forget(fn))
+  expect_true(forget(fnm))
+  expect_equal(fnm(), 5)
+
+  expect_true(drop_cache(fnm)())
+  expect_equal(fnm(), 6)
+
+  expect_true(is.memoised(fnm))
+  expect_false(is.memoised(fn))
+})
+
+teardown({
+    AzureStor::delete_blob_container(bl_endp, cache_name, confirm = FALSE)
+})