Thread-safe alternative to File::Tee?

Question

I was wanting to implement some logging for a threaded script I have, and I came across File::Tee. However, when attempting to ppm the module on a Windows box, it's not found (and according to activestate, not supported on Windows).

I really liked that you could lock file access though, by doing something like:

tee STDOUT, {mode => '>>', open => '$ENV{DOM}\\threaded_build.log', lock => 1};
tee STDERR, {mode => '>>', open => '$ENV{DOM}\\threaded_debug.log', lock => 1};

Is there a cross-platform, thread-safe alternative?

Answer 1

File::Tee takes extra care to handle output generated by external programs run through system or XS code that doesn't go through perlio. I think that's what makes it incompatible with Windows.

IO::Tee is more cross-platform and I don't think making it thread safe would be too hard to do. The sync code in File::Tee just looks like:

                    flock($teefh, LOCK_EX) if $target->{lock};
                    print $teefh $cp;
                    flock($teefh, LOCK_UN) if $target->{lock};

You could accomplish the same thing in IO::Tee by modifying a couple of methods:

use Fcntl ':flock';

no warnings 'redefine';
sub IO::Tee::PRINT
{
    my $self = shift;
    my $ret = 1;
    foreach my $fh (@$self) {
        flock($fh, LOCK_EX);
        undef $ret unless print $fh @_;
        flock($fh, LOCK_UN);
    }
    return $ret;
}
sub IO::Tee::PRINTF
{
    my $self = shift;
    my $fmt = shift;
    my $ret = 1;
    foreach my $fh (@$self) { 
        flock($fh, LOCK_EX);
        undef $ret unless printf $fh $fmt, @_;
        flock($fh, LOCK_UN);
    }
    return $ret;
}