safeio

An OTP application for checking that specific directories are safe to use.

This project is the result of problems with handling broken NFS mounts.

Our application would regularily use filelib:is_regular/1 with a path that is in an NFS mounted directory.

The problem is, whenever such a mount point gets stuck, e.g. because of an NFS-server outage or a network problem, all file operations, i.e. calls to file and filelib modules, block from the moment the first path in a stuck directory is accessed. Even operations on paths outside the broken mount point are blocked.

This library aims to provide a workaround for this problem by providing operations that check if a path is accessable using an external process instead of filelib or file.

The library will also try to recognize when an NFS mount is available again. This is done by periodically killing the external port process (when a stale mount is detected) and retrying the stat operation.

Build

$ rebar3 compile

Usage

To check if a file is a regular file, use safeio:is_regular/2:

safeio:is_regular("/mnt/nfs-audio", "en/wav-g711a/test.wav"),
...