AzureStor (version 2.0.1)

list_azure_files: Operations on a file share

Description

Upload, download, or delete a file; list files in a directory; create or delete directories.

Usage

list_azure_files(share, dir, info = c("all", "name"), prefix = NULL)
upload_azure_file(share, src, dest, blocksize = 2^22,
  use_azcopy = FALSE)
multiupload_azure_file(share, src, dest, blocksize = 2^22,
  use_azcopy = FALSE, max_concurrent_transfers = 10)
download_azure_file(share, src, dest, overwrite = FALSE,
  use_azcopy = FALSE)
multidownload_azure_file(share, src, dest, overwrite = FALSE,
  use_azcopy = FALSE, max_concurrent_transfers = 10)
delete_azure_file(share, file, confirm = TRUE)
create_azure_dir(share, dir)
delete_azure_dir(share, dir, confirm = TRUE)

Arguments

share

A file share object.

dir, file

A string naming a directory or file respectively.

info

Whether to return names only, or all information in a directory listing.

prefix

For list_azure_files, filters the result to return only files and directories whose name begins with this prefix.

src, dest

The source and destination files for uploading and downloading. For uploading, src can also be a textConnection or rawConnection object to allow transferring in-memory R objects without creating a temporary file.

blocksize

The number of bytes to upload per HTTP(S) request.

use_azcopy

Whether to use the AzCopy utility from Microsoft to do the transfer, rather than doing it in R.

max_concurrent_transfers

For multiupload_azure_file and multidownload_azure_file, the maximum number of concurrent file transfers. Each concurrent file transfer requires a separate R process, so limit this if you are low on memory.

overwrite

When downloading, whether to overwrite an existing destination file.

confirm

Whether to ask for confirmation on deleting a file or directory.

Value

For list_azure_files, if info="name", a vector of file/directory names. If info="all", a data frame giving the file size and whether each object is a file or directory.

For download_azure_file, if dest=NULL, the contents of the downloaded file as a raw vector.

Details

upload_azure_file and download_azure_file are the workhorse file transfer functions for file storage. They each take as inputs a single filename or connection as the source for uploading/downloading, and a single filename as the destination.

multiupload_azure_file and multidownload_azure_file are functions for uploading and downloading multiple files at once. They parallelise file transfers by deploying a pool of R processes in the background, which can lead to significantly greater efficiency when transferring many small files. They take as input a wildcard pattern as the source, which expands to one or more files. The dest argument should be a directory.

The file transfer functions also support working with connections to allow transferring R objects without creating temporary files. For uploading, src can be a textConnection or rawConnection object. For downloading, dest can be NULL or a rawConnection object. In the former case, the downloaded data is returned as a raw vector, and for the latter, it will be placed into the connection. See the examples below.

By default, download_azure_file will display a progress bar as it is downloading. To turn this off, use options(azure_dl_progress_bar=FALSE). To turn the progress bar back on, use options(azure_dl_progress_bar=TRUE).

See Also

file_share, az_storage, storage_download, call_azcopy

AzCopy version 10 on GitHub

Examples

# NOT RUN {
share <- file_share("https://mystorage.file.core.windows.net/myshare", key="access_key")

list_azure_files(share, "/")
list_azure_files(share, "/", recursive=TRUE)

create_azure_dir(share, "/newdir")

upload_azure_file(share, "~/bigfile.zip", dest="/newdir/bigfile.zip")
download_azure_file(share, "/newdir/bigfile.zip", dest="~/bigfile_downloaded.zip")

delete_azure_file(share, "/newdir/bigfile.zip")
delete_azure_dir(share, "/newdir")

# uploading/downloading multiple files at once
multiupload_azure_file(share, "/data/logfiles/*.zip")
multidownload_azure_file(share, "/monthly/jan*.*", "/data/january")

# uploading serialized R objects via connections
json <- jsonlite::toJSON(iris, pretty=TRUE, auto_unbox=TRUE)
con <- textConnection(json)
upload_azure_file(share, con, "iris.json")

rds <- serialize(iris, NULL)
con <- rawConnection(rds)
upload_azure_file(share, con, "iris.rds")

# downloading files into memory: as a raw vector, and via a connection
rawvec <- download_azure_file(share, "iris.json", NULL)
rawToChar(rawvec)

con <- rawConnection(raw(0), "r+")
download_azure_file(share, "iris.rds", con)
unserialize(con)

# }