#!/usr/bin/perl

use strict;
use Benchmark;
use File::Find ();

my @found;
my $ext = '';

if ( @ARGV >= 2 and $ARGV[0] eq '-e' ) {
    shift;
    $ext = shift;
}
my @paths = ( @ARGV ) ? @ARGV : ( "." );
die "Usage: $0 [-e ext] path ...\n" unless ( -d $paths[0] );

timethese( 10, {
        '2File::Find' => \&try_File_Find,
        '1Readin_dir' => \&try_readin_dir,
        '0Unix_find'  => \&try_unix_find,
    } );

sub try_File_Find
{
    @found = ();
    File::Find::find( { 
            wanted => \&wanted,
        #    follow_fast => 1,
        }, @paths );
    print "File::Find found ".scalar @found." matches:\n";
}
sub try_readin_dir
{
    @found = ();
    readin_dir( \@found, \@paths, $ext );
    print "readin_dir found ".scalar @found." matches\n";
}
sub try_unix_find
{
    @found = ();
    my $cmd = "find @paths -type f";
    open( FIND, "-|", $cmd );
    while (<FIND>) {
        chomp;
        push @found, $_ if ( $ext eq '' or /\.$ext$/ );
    }
    print "unix_find found ".scalar @found." matches\n"; #, join( "\n",@found,"" );
}

sub wanted
{
    push @found, $File::Find::name if ( $ext eq '' or /\.$ext$/ );
}

sub readin_dir
{
    my ( $filenames, $paths, $ext ) = @_;

    for my $path ( @$paths ) {
        $path =~ s{/+$}{};   # don't need or want trailing slash(es)
        opendir( my $dh, $path ) or do { warn "readin_dir: open failed for $path\n"; next };
        my @subdirs = ();
        while ( my $file = readdir( $dh )) {
            next if ( $file =~ /^\.{1,2}$/ );
            if ( -d "$path/$file" ) {
                push @subdirs, "$path/$file";
            }
            elsif ( $ext eq '' or $file =~ /\.$ext$/ ) {
                push @$filenames, "$path/$file";
            }
        }
        closedir( $dh );
        readin_dir( $filenames, \@subdirs, $ext ) if ( @subdirs );
    }
}