IO::Async::Loop::Epoll - use IO::Async with epoll on Linux


   use IO::Async::Loop::Epoll;

   use IO::Async::Stream;
   use IO::Async::Signal;

   my $loop = IO::Async::Loop::Epoll->new;

   $loop->add( IO::Async::Stream->new(
         read_handle => \*STDIN,
         on_read => sub {
            my ( $self, $buffref ) = @_;
            while( $$buffref =~ s/^(.*)\r?\n// ) {
               print "You said: $1\n";
   ) );

   $loop->add( IO::Async::Signal->new(
         name => 'INT',
         on_receipt => sub {
            print "SIGINT, will now quit\n";
   ) );



This subclass of IO::Async::Loop uses epoll(7) on Linux to perform read-ready and write-ready tests so that the O(1) high-performance multiplexing of Linux's epoll_pwait(2) syscall can be used.

The epoll Linux subsystem uses a persistent registration system, meaning that better performance can be achieved in programs using a large number of filehandles. Each epoll_pwait(2) syscall only has an overhead proportional to the number of ready filehandles, rather than the total number being watched. For more detail, see the epoll(7) manpage.

This class uses the epoll_pwait(2) system call, which atomically switches the process's signal mask, performs a wait exactly as epoll_wait(2) would, then switches it back. This allows a process to block the signals it cares about, but switch in an empty signal mask during the poll, allowing it to handle file IO and signals concurrently.



   $loop = IO::Async::Loop::Epoll->new()

This function returns a new instance of a IO::Async::Loop::Epoll object.


As this is a subclass of IO::Async::Loop, all of its methods are inherited. Expect where noted below, all of the class's methods behave identically to IO::Async::Loop.


   $count = $loop->loop_once( $timeout )

This method calls epoll_pwait(2), and processes the results of that call. It returns the total number of IO::Async::Notifier callbacks invoked, or undef if the underlying epoll_pwait() method returned an error. If the epoll_pwait() was interrupted by a signal, then 0 is returned instead.



Paul Evans <>