Check if is folder empty

General Usage Performance
5

That was really valuable feedback. Looking into the code I could come up with my own

function isemptydir(dir::AbstractString)
    # Allocate space for uv_fs_t struct
    req = Libc.malloc(Base.Filesystem._sizeof_uv_fs)
    ie = false
    try
        # defined in sys.c, to call uv_fs_readdir, which sets errno on error.
        err = ccall(:uv_fs_scandir, Int32, (Ptr{Cvoid}, Ptr{Cvoid}, Cstring, Cint, Ptr{Cvoid}),
                    C_NULL, req, dir, 0, C_NULL)
        err < 0 && Base.Filesystem.uv_error("readdir($(repr(dir)))", err)

        # iterate the listing into entries
        ent = Ref{Base.Filesystem.uv_dirent_t}()
        ie = Base.UV_EOF == ccall(:uv_fs_scandir_next, Cint, (Ptr{Cvoid}, Ptr{Base.Filesystem.uv_dirent_t}), req, ent)

        # Clean up the request string
        Base.Filesystem.uv_fs_req_cleanup(req)
    finally
        Libc.free(req)
    end
    return ie
end

and with this I see a significant but not large difference in memory consumption and performance on a mac-os:

julia> @btime isemptydir("temp/hh")
  48.199 ms (0 allocations: 0 bytes)
false

julia> @btime isempty(readdir("temp/hh"))
  50.958 ms (110028 allocations: 5.18 MiB)
false
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