NAME¶
Linux::FD::Event - Event filehandles for Linux
SYNOPSIS¶
use Linux::FD::Event;
my $foo = Linux::FD::Event->new(42);
if (fork) {
say $foo->get while sleep 1
}
else {
$foo->add($_) while <>;
}
METHODS¶
new($initial_value, @flags)¶
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. This 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.