NAME

       Linux::FD::Event - Event filehandles for Linux

VERSION

       version 0.014

SYNOPSIS

        use Linux::FD::Event;

        my $foo = Linux::FD::Event->new(42);
        if (fork) {
            say $foo->get while sleep 1
        }
        else {
            $foo->add($_) while <>;
        }

DESCRIPTION

       This creates an eventfd object that can be used as an event wait/notify mechanism by
       userspace applications, and by the kernel to notify userspace applications of events. The
       object contains an unsigned 64-bit integer counter that is maintained by the kernel. It
       has two modes, default and semaphore, that differ only in "get" behavior as described
       below.

METHODS

   new($initial_value, @flags)
       This creates a new eventfd filehandler. The counter is initialized with the value
       specified in the argument $initial_value. @flags is an optional list of flags, currently
       limited to 'non-blocking' (requires Linux 2.6.27), and 'semaphore' (requires Linux
       2.6.30).

   get()
       If the eventfd counter has a non-zero value, and 'semaphore' is not set, then a "get"
       returns 64 bit unsigned integer containing that value, and the counter's value is reset to
       zero. If 'semaphore' is set, it decrements the counter by one and returns one. In either
       case, if the counter is zero at the time of the "get", then the call either blocks until
       the counter becomes non-zero, or fails with the error EAGAIN if the file handle has been
       made non-blocking.

   add($value)
       A "add" call adds the 64 bit unsigned integer value $value to the counter. The maximum
       value that may be stored in the counter is the largest unsigned 64-bit value minus 1
       (i.e., 0xfffffffffffffffe). If the addition would cause the counter's value to exceed the
       maximum, then the "add" either blocks until a "get" is performed on the file descriptor,
       or fails with the error EAGAIN if the file descriptor has been made non-blocking. A "add"
       will fail with the error EINVAL if an attempt is made to write the value
       0xffffffffffffffff.

AUTHOR

       Leon Timmermans <leont@cpan.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2010 by Leon Timmermans.

       This is free software; you can redistribute it and/or modify it under the same terms as
       the Perl 5 programming language system itself.