dirent - Iterative directory listing library

Version: 1.0.0

dirent

dirent is an iterative directory listing for Erlang.

Erlang functions such as filelib:fold_files/5, file:list_dir/1, c:ls/0,1, etc return files from directories after reading them from the filesystem. When you have an humongous number of files on a single folder, all these functions will block for a certain time.

In these cases you may not be interested in returning the full list of files, but instead you may want to list them iteratively, returning each entry after the another to your process, at the moment they are taken from readdir.

Installation

Download the sources from our Github repository

To build the application simply run rebar3 compile.

Or add it to your rebar config add:


{deps, [
    ....
    {dirent, ".*", {git, "git://github.com/team-telnyx/dirent.git", {branch, "master"}}}
]}.

Basic usage

The most basic usage of dirent is:

> {ok, Dir} = dirent:opendir(".").
{ok,#Ref<0.1857889054.1430650882.66300>}
> dirent:readdir(Dir).
"LICENSE"
> dirent:readdir(Dir).
"README.md"
> dirent:readdir(Dir).
"rebar.config"
...
> dirent:readdir(Dir).
finished

But you can also use the functions dirent:foreach/2 and dirent:fold/3.

For example, to print all files in the folder, one per line, do:

dirent:foreach(".", fun(F) -> io:fwrite("~s~n", [F]), cont end).

and if you need to collect all files from a folder in a list, do:

dirent:fold(".", fun(F, Tail) -> {cont, [F | Tail]} end, []).

The dirent:foreach/2 function Fun can return cont or halt. In the former case, the loop will continue reading files, while in the latter case the loop will halt and the function will return ok.

The dirent:fold/3 function Fun can return {cont, AccOut} or {halt, AccOut}, likewise the above, but also returning the accumulator, which is passed to the {ok, AccOut} return value.