ScanDir.jl

Faster reading of directories

This package provides two functions:

• scandir, which returns a vector of DirEntry objects, each specifying a filename and a type (file, directory, link etc.).
• ScanDir.walkdir, which is a faster version of Base.walkdir, using scandir to avoid unnecessary stat calls.

Julia's builtin readdir function returns filenames in a directory but discards the type information returned from the underlying libuv function call. The scandir function exposes this information in the DirEntry struct. The name scandir was chosen to parallel python's os.scandir, which offers similar functionality.

Benchmarks of ScanDir.walkdir on one Windows machine have shown a speedup factor of 4~4.5 on a local drive, and 30~35 (!) on a network-mapped drive, compared to Base.walkdir.

Usage

scandir(path::AbstractString=".") returns a vector of DirEntry. Each DirEntry's filename is accessible via the name field. Its type can be queried by the standard Base functions (isfile, isdir, islink, isfifo, issocket, ischardev, isblockdev). This will only call stat if necessary -- which happens if the entry is a symlink and the type of the target needs to be determined. In this case, the link is followed from the path supplied to scandir, so the result may depend on the working directory if that path is relative.

julia> dir = mktempdir();
julia> cd(dir)
julia> mkdir("subdir");
julia> touch("file");
julia> symlink("subdir", "link")
julia> entries = scandir()
3-element Vector{DirEntry}:
 <file "./file">
 <link "./link">
 <directory "./subdir">

julia> isdir.(entries) # triggers `stat` call for "link" only
3-element BitArray{1}:
 0
 1
 1

ScanDir.walkdir is a faster implementation of Base.walkdir (https://docs.julialang.org/en/v1/base/file/#Base.Filesystem.walkdir), and has a compatible interface. Its interface differs from Base.walkdir in two ways:

• it returns named tuples (root=..., dirs=..., file=...)
• it supports a prune keyword argument to filter the returned contents.

julia> touch("subdir/file2");
julia> mkdir("subdir/skipme");
julia> touch("subdir/skipme/file3");
julia> collect(ScanDir.walkdir("."))
3-element Array{Any,1}:
 (root = ".", dirs = ["subdir"], files = ["file", "link"])
 (root = ".\\subdir", dirs = ["skipme"], files = ["file2"])
 (root = ".\\subdir\\skipme", dirs = String[], files = ["file3"])

julia> collect(ScanDir.walkdir(".", prune = e->startswith(e.name, "skip")))
2-element Array{Any,1}:
 (root = ".", dirs = ["subdir"], files = ["file", "link"])
 (root = ".\\subdir", dirs = String[], files = ["file2"])