[ViewVC] Diff of: cvs/EV/EV.pm

Comparing EV/EV.pm (file contents):
Revision 1.54 by root, Tue Nov 27 07:27:10 2007 UTC vs.
Revision 1.72 by root, Thu Dec 20 07:12:57 2007 UTC

 This module provides an interface to libev
 (L<http://software.schmorp.de/pkg/libev.html>). While the documentation
 below is comprehensive, one might also consult the documentation of libev
 itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
 watcher semantics or some discussion on the available backends, or how to
-force a specific backend with C<LIBEV_FLAGS>.
+force a specific backend with C<LIBEV_FLAGS>, or just about in any case
+because it has much more detailed information.
 =cut
 package EV;
 use strict;
 BEGIN {
-   our $VERSION = '1.4';
+   our $VERSION = '2.0';
    use XSLoader;
    XSLoader::load "EV", $VERSION;
 }
 @EV::IO::ISA       =
 @EV::Timer::ISA    =
 @EV::Periodic::ISA =
 @EV::Signal::ISA   =
+@EV::Child::ISA    =
+@EV::Stat::ISA     =
 @EV::Idle::ISA     =
 @EV::Prepare::ISA  =
 @EV::Check::ISA    =
-@EV::Child::ISA    =
 @EV::Embed::ISA    =
-@EV::Stat::ISA     = "EV::Watcher";
+@EV::Fork::ISA     =
+   "EV::Watcher";
+@EV::Loop::Default::ISA = "EV::Loop";
 =head1 BASIC INTERFACE
 =over 4
 =item $EV::DIED
 Must contain a reference to a function that is called when a callback
-throws an exception (with $@ containing thr error). The default prints an
+throws an exception (with $@ containing the error). The default prints an
 informative message and continues.
 If this callback throws an exception it will be silently ignored.
 =item $time = EV::time
 When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
 innermost call to EV::loop return.
 When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
 fast as possible.
+=item $count = EV::loop_count
+Return the number of times the event loop has polled for new
+events. Sometiems useful as a generation counter.
 =item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
 This function rolls together an I/O and a timer watcher for a single
 one-shot event without the need for managing a watcher object.
 EV::once doesn't return anything: the watchers stay active till either
 of them triggers, then they will be stopped and freed, and the callback
 invoked.
+=item EV::feed_fd_event ($fd, $revents)
+Feed an event on a file descriptor into EV. EV will react to this call as
+if the readyness notifications specified by C<$revents> (a combination of
+C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
+=item EV::feed_signal_event ($signal)
+Feed a signal event into EV. EV will react to this call as if the signal
+specified by C<$signal> had occured.
 =back
 =head2 WATCHER OBJECTS
 A watcher is an object that gets created to record your interest in some
 event. For instance, if you want to wait for STDIN to become readable, you
 events.
 Each watcher type has its associated bit in revents, so you can use the
 same callback for multiple watchers. The event mask is named after the
 type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
-EV::periodic sets EV::PERIODIC and so on, with the exception of IO events
+EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
 (which can set both EV::READ and EV::WRITE bits), and EV::timer (which
 uses EV::TIMEOUT).
 In the rare case where one wants to create a watcher but not start it at
 the same time, each constructor has a variant with a trailing C<_ns> in
 =item $w->stop
 Stop a watcher if it is active. Also clear any pending events (events that
 have been received but that didn't yet result in a callback invocation),
-regardless of wether the watcher was active or not.
+regardless of whether the watcher was active or not.
 =item $bool = $w->is_active
 Returns true if the watcher is active, false otherwise.
 The default priority of any newly-created watcher is 0.
 Note that the priority semantics have not yet been fleshed out and are
 subject to almost certain change.
-=item $w->trigger ($revents)
+=item $w->invoke ($revents)
 Call the callback *now* with the given event mask.
+=item $w->feed_event ($revents)
+Feed some events on this watcher into EV. EV will react to this call as if
+the watcher had received the given C<$revents> mask.
+=item $revents = $w->clear_pending
+If the watcher is pending, this function returns clears its pending status
+and returns its C<$revents> bitset (as if its callback was invoked). If the
+watcher isn't pending it does nothing and returns C<0>.
 =item $previous_state = $w->keepalive ($bool)
 Normally, C<EV::loop> will return when there are no active watchers
 (which is a "deadlock" because no progress can be made anymore). This is
 though your watcher is active, it won't keep C<EV::loop> from returning.
 The initial value for keepalive is true (enabled), and you cna change it
 any time.
-Example: Register an IO watcher for some UDP socket but do not keep the
+Example: Register an I/O watcher for some UDP socket but do not keep the
 event loop from running just because of that watcher.
    my $udp_socket = ...
    my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
    $udp_watcher->keepalive (0);
 =head2 WATCHER TYPES
 Each of the following subsections describes a single watcher type.
-=head3 IO WATCHERS - is this file descriptor readable or writable?
+=head3 I/O WATCHERS - is this file descriptor readable or writable?
 =over 4
 =item $w = EV::io $fileno_or_fh, $eventmask, $callback
 =item $w->again
 Simply stops and starts the watcher again.
+=item $time = $w->at
+Return the time that the watcher is expected to trigger next.
 =back
 =head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
 watcher for all pids).
 =back
+=head3 STAT WATCHERS - did the file attributes just change?
+=over 4
+=item $w = EV::stat $path, $interval, $callback
+=item $w = EV::stat_ns $path, $interval, $callback
+Call the callback when a file status change has been detected on
+C<$path>. The C<$path> does not need to exist, changing from "path exists"
+to "path does not exist" is a status change like any other.
+The C<$interval> is a recommended polling interval for systems where
+OS-supported change notifications don't exist or are not supported. If
+you use C<0> then an unspecified default is used (which is highly
+recommended!), which is to be expected to be around five seconds usually.
+This watcher type is not meant for massive numbers of stat watchers,
+as even with OS-supported change notifications, this can be
+resource-intensive.
+The C<stat_ns> variant doesn't start (activate) the newly created watcher.
+=item ... = $w->stat
+This call is very similar to the perl C<stat> built-in: It stats (using
+C<lstat>) the path specified in the watcher and sets perls stat cache (as
+well as EV's idea of the current stat values) to the values found.
+In scalar context, a boolean is return indicating success or failure of
+the stat. In list context, the same 13-value list as with stat is returned
+(except that the blksize and blocks fields are not reliable).
+In the case of an error, errno is set to C<ENOENT> (regardless of the
+actual error value) and the C<nlink> value is forced to zero (if the stat
+was successful then nlink is guaranteed to be non-zero).
+See also the next two entries for more info.
+=item ... = $w->attr
+Just like C<< $w->stat >>, but without the initial stat'ing: this returns
+the values most recently detected by EV. See the next entry for more info.
+=item ... = $w->prev
+Just like C<< $w->stat >>, but without the initial stat'ing: this returns
+the previous set of values, before the change.
+That is, when the watcher callback is invoked, C<< $w->prev >> will be set
+to the values found I<before> a change was detected, while C<< $w->attr >>
+returns the values found leading to the change detection. The difference (if any)
+between C<prev> and C<attr> is what triggered the callback.
+If you did something to the filesystem object and do not want to trigger
+yet another change, you can call C<stat> to update EV's idea of what the
+current attributes are.
+=item $w->set ($path, $interval)
+Reconfigures the watcher, see the constructor above for details. Can be
+called at any time.
+=item $current_path = $w->path
+=item $old_path = $w->path ($new_path)
+Returns the previously set path and optionally set a new one.
+=item $current_interval = $w->interval
+=item $old_interval = $w->interval ($new_interval)
+Returns the previously set interval and optionally set a new one. Can be
+used to query the actual interval used.
+=back
 =head3 IDLE WATCHERS - when you've got nothing better to do...
 =over 4
 =item $w = EV::idle $callback
 =item $w = EV::idle_ns $callback
-Call the callback when there are no pending io, timer/periodic, signal or
+Call the callback when there are no other pending watchers of the same or
-child events, i.e. when the process is idle.
+higher priority (excluding check, prepare and other idle watchers of the
+same or lower priority, of course). They are called idle watchers because
+when the watcher is the highest priority pending event in the process, the
+process is considered to be idle at that priority.
+If you want a watcher that is only ever called when I<no> other events are
+outstanding you have to set the priority to C<EV::MINPRI>.
 The process will not block as long as any idle watchers are active, and
 they will be called repeatedly until stopped.
+For example, if you have idle watchers at priority C<0> and C<1>, and
+an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
+and the I/O watcher will always run when ready. Only when the idle watcher
+at priority C<1> is stopped and the I/O watcher at priority C<0> is not
+pending with the C<0>-priority idle watcher be invoked.
 The C<idle_ns> variant doesn't start (activate) the newly created watcher.
 =back
          or return;
       # make the dispatcher handle any outstanding stuff
       ... not shown
-      # create an IO watcher for each and every socket
+      # create an I/O watcher for each and every socket
       @snmp_watcher = (
          (map { EV::io $_, EV::READ, sub { } }
              keys %{ $dispatcher->{_descriptors} }),
          EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
 The C<check_ns> variant doesn't start (activate) the newly created watcher.
 =back
-=head3 STAT WATCHERS - did the file stats just change?
-=over 4
+=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
-=item $w = EV::stat $path, $interval, $callback
+Fork watchers are called when a C<fork ()> was detected. The invocation
+is done before the event loop blocks next and before C<check> watchers
+are being called, and only in the child after the fork.
-=item $w = EV::stat_ns $path, $interval, $callback
+=over 4
-Call the callback when a file status change has been detected on
+=item $w = EV::fork $callback
-C<$path>. The C<$path> does not need to exist, changing from "path exists"
-to "path does not exist" is a status change like any other.
-The C<$interval> is a recommended polling interval for systems where
+=item $w = EV::fork_ns $callback
-OS-supported change notifications don't exist or are not supported. If
-you use C<0> then an unspecified default is used (which is highly
-recommended!), which is to be expected to be around five seconds usually.
-This watcher type is not meant for massive numbers of stat watchers,
+Call the callback before the event loop is resumed in the child process
-as even with OS-supported change notifications, this can be
+after a fork.
-resource-intensive.
-The C<stat_ns> variant doesn't start (activate) the newly created watcher.
+The C<fork_ns> variant doesn't start (activate) the newly created watcher.
-=item $w->set ($path, $interval)
-Reconfigures the watcher, see the constructor above for details. Can be
-called at any time.
-=item $current_path = $w->path
-=item $old_path = $w->path ($new_path)
-Returns the previously set path and optionally set a new one.
-=item $current_interval = $w->interval
-=item $old_interval = $w->interval ($new_interval)
-Returns the previously set interval and optionally set a new one. Can be
-used to query the actual interval used.
 =back
+=head1 PERL SIGNALS
+While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
+with EV is as the same as any other C library: Perl-signals will only be
+handled when Perl runs, which means your signal handler might be invoked
+only the next time an event callback is invoked.
+The solution is to use EV signal watchers (see C<EV::signal>), which will
+ensure proper operations with regards to other event watchers.
+If you cannot do this for whatever reason, you can also force a watcher
+to be called on every event loop iteration by installing a C<EV::check>
+watcher:
+   my $async_check = EV::check sub { };
+This ensures that perl shortly gets into control for a short time, and
+also ensures slower overall operation.
 =head1 THREADS
 Threads are not supported by this module in any way. Perl pseudo-threads
 is evil stuff and must die. As soon as Perl gains real threads I will work
 our $DIED = sub {
    warn "EV: error in callback (ignoring): $@";
 };
 default_loop
-   or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?';
+   or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
 1;
 =head1 SEE ALSO
-L<EV::DNS>.
+L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
+event loop), L<Coro::EV> (efficient coroutines with EV).
 =head1 AUTHOR
  Marc Lehmann <schmorp@schmorp.de>
  http://home.schmorp.de/

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Comparing EV/EV.pm (file contents): Revision 1.54 by root, Tue Nov 27 07:27:10 2007 UTC vs. Revision 1.72 by root, Thu Dec 20 07:12:57 2007 UTC

Diff Legend

Comparing EV/EV.pm (file contents):
Revision 1.54 by root, Tue Nov 27 07:27:10 2007 UTC vs.
Revision 1.72 by root, Thu Dec 20 07:12:57 2007 UTC