NAME `IO::Ppoll' - Object interface to Linux's `ppoll()' call SYNOPSIS use IO::Ppoll qw( POLLIN POLLOUT ); use POSIX qw( sigprocmask SIG_BLOCK SIGHUP ); my $ppoll = IO::Ppoll->new(); $ppoll->mask( $input_handle => POLLIN ); $ppoll->mask( $output_handle => POLLOUT ); $SIG{HUP} = sub { print "SIGHUP happened\n"; }; sigprocmask( SIG_BLOCK, POSIX::SigSet->new( SIGHUP ), undef ); # If a SIGHUP happens, it can only happen during this poll $ppoll->poll( $timeout ); $input_ev = $poll->events( $input_handle ); DESCRIPTION `IO::Ppoll' is a simple interface to Linux's `ppoll()' system call. It provides an interface that is drop-in compatible with IO::Poll. The object stores a signal mask that will be in effect during the actual `ppoll()' system call and has additional methods for manipulating the signal mask. The `ppoll()' system call atomically switches the process's signal mask to that provided by the call, waits identically to `poll()', then switches it back again. This allows a program to safely wait on either file handle IO or signals, without needing such tricks as a self-connected pipe or socket. The usual way in which this is used is to block the signals the application is interested in during the normal running of code. Whenever the `ppoll()' wait is entered the process signal mask will be switched to that stored in the object. If there are any pending signals, the Linux kernel will then deliver them and make `ppoll()' return -1 with `errno' set to `EINTR'. If no signals are pending, it will wait as a normal `poll()' would. This guarantees the signals will only be delivered during the `ppoll()' wait, when it would be safe to do so. CONSTRUCTOR $ppoll = IO::Ppoll->new() Returns a new instance of an `IO::Ppoll' object. It will contain no file handles and its signal mask will be empty. METHODS $mask = $ppoll->mask( $handle ) Returns the current mask bits for the given IO handle $ppoll->mask( $handle, $newmask ) Sets the mask bits for the given IO handle. If `$newmask' is 0, the handle will be removed. $ret = $ppoll->poll( $timeout ) Call the `ppoll()' system call. If `$timeout' is not supplied then no timeout value will be passed to the system call. Returns the result of the system call, which is the number of filehandles that have non-zero events, 0 on timeout, or -1 if an error occurred (including being interrupted by a signal). If -1 is returned, `$!' will contain the error. $bits = $ppoll->events( $handle ) Returns the event mask which represents the events that happened on the filehandle during the last call to `poll()'. $ppoll->remove( $handle ) Removes the handle from the list of file descriptors for the next poll. @handles = $ppoll->handles( $bits ) Returns a list of handles. If `$bits' is not given then all of the handles will be returned. If `$bits' is given then the list will only contain handles which reported at least one of the bits specified during the last `poll()' call. $sigset = $ppoll->sigmask Returns the `POSIX::SigSet' object in which the signal mask is stored. Since this is a reference to the object the `IO::Ppoll' object uses, any modifications made to it will be reflected in the signal mask given to the `ppoll()' system call. $ppoll->sigmask( $newsigset ) Sets the `POSIX::SigSet' object in which the signal mask is stored. Usually this is not required, as a new `IO::Ppoll' is initialised with an empty set, and the `sigmask_add()' and `sigmask_del()' methods can be used to modify it. $ppoll->sigmask_add( @signals ) Adds the given signals to the signal mask. These signals will be blocked during the `poll()' call. $ppoll->sigmask_del( @signals ) Removes the given signals from the signal mask. These signals will not be blocked during the `poll()' call, and may be delivered while `poll()' is waiting. $present = $ppoll->sigmask_ismember( $signal ) Tests if the given signal is present in the signal mask. SEE ALSO * IO::Poll - Object interface to system poll call * `ppoll(2)' - wait for some event on a file descriptor (Linux manpages) * IO::Async::Loop::IO_Ppoll - a Loop using an IO::Ppoll object AUTHOR Paul Evans