I'm getting a race condition in some Linux::Inotify2 code. Where I'm watching a directory for IN_CREATE events to process the created files. The following works perfectly 99% of the time.

use strict;
use warnings;
use XML::LibXML;
use Linux::Inotify2;

my $drop_dir = "/foo/bar";

my $inotify = Linux::Inotify2->new
    or die "unable to create new inotify object: $!";

$inotify->watch($drop_dir, IN_CREATE, sub {
    my $e = shift;
    my $name = $e->fullname;
    process_drop_file($name);
});

1 while $inotify->poll;

sub process_drop_file {
    my $file = Path::Class::File->new(shift);
    -f $file or croak "'$file' is not a file";
    my $doc = XML::LibXML->new->parse_file("$file");
    # Do stuff with it...
    $file->remove or croak "Couldn't remove '$file'";
}

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But then bam-

/foo/bar/test.xml:1: parser error : Start tag expected, '<' not found

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The file is there and in tact by the time I can manually check of course but XML::LibXML tried to read it too early. This means it passed the -f but had no content, I think.

Among several other dead-ends, like playing with the cookie and watch args, I tried this-

$inotify->watch($drop_dir, IN_CREATE, sub {
    my $e = shift;
    my $name = $e->fullname;
    $inotify->watch($name, IN_CLOSE, sub {
        process_drop_file($name);
    });
});

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-in a misguided attempt to move the event check to the file, but of course this could only succeed in the 1 in 100 case where the race condition hits.

What am I missing or doing wrong? Thank you!

In reply to Race condition in Linux::Inotify2 between dir and new file? by Your Mother

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