Coro/Event/Event.pm

=head1 NAME

Coro::Event - do events the coro-way, with Event

=head1 SYNOPSIS

 use Coro;
 use Coro::Event;

 sub keyboard : Coro {
    my $w = Coro::Event->io(fd => \*STDIN, poll => 'r');
    while() {
       print "cmd> ";
       my $ev = $w->next; my $cmd = <STDIN>;
       unloop unless $cmd ne "";
       print "data> ";
       my $ev = $w->next; my $data = <STDIN>;
    }
 }

 loop;

 # wait for input on stdin for one second
 Coro::Event::do_io (fd => \*STDIN, timeout => 1) & Event::Watcher::R
    or die "no input received";

 # use a separate thread for event processing, if impossible in main:
 Coro::async { Event::loop };

=head1 DESCRIPTION

This module enables you to create programs using the powerful Event model
(and module), while retaining the linear style known from simple or
threaded programs.

This module provides a method and a function for every watcher type
(I<flavour>) (see L<Event>). The only difference between these and the
watcher constructors from Event is that you do not specify a callback
function - it will be managed by this module.

Your application should just create all necessary threads and then call
C<Event::loop>.

Please note that even programs or modules (such as L<Coro::Handle>) that
use "traditional" event-based/continuation style will run more efficient
with this module then when using only Event.

=head1 WARNING

Please note that Event does not support multithreading. That means that
you B<MUST NOT> block in an event callback. Again: In Event callbacks,
you I<must never ever> call a Coro function that blocks the current
thread.

While this seems to work superficially, it will eventually cause memory
corruption and often results in deadlocks.

Best practise is to always use B<Coro::unblock_sub> for your callbacks.

=head1 SEMANTICS

Whenever Event blocks (e.g. in a call to C<one_event>, C<loop> etc.),
this module cede's to all other threads with the same or higher
priority. When any threads of lower priority are ready, it will not
block but run one of them and then check for events.

The effect is that coroutines with the same or higher priority than
the blocking coroutine will keep Event from checking for events, while
coroutines with lower priority are being run, but Event checks for new
events after every cede. Note that for this to work you actually need to
run the event loop in some thread.

=head1 FUNCTIONS

=over 4

=cut

package Coro::Event;

no warnings;

use Carp;
no warnings;

use Coro;
use Event qw(loop unloop); # we are re-exporting this for historical reasons

use XSLoader;

use base Exporter::;

our @EXPORT = qw(loop unloop sweep);

BEGIN {
   our $VERSION = 5.132;

   local $^W = 0; # avoid redefine warning for Coro::ready;
   XSLoader::load __PACKAGE__, $VERSION;
}

=item $w = Coro::Event->flavour (args...)

Create and return a watcher of the given type.

Examples:

  my $reader = Coro::Event->io (fd => $filehandle, poll => 'r');
  $reader->next;

=cut

=item $w->next

Wait for and return the next event of the event queue of the watcher. The
returned event objects support two methods only: C<hits> and C<got>, both
of which return integers: the number this watcher was hit for this event,
and the mask of poll events received.

=cut

=item do_flavour args...

Create a watcher of the given type and immediately call it's next method,
returning the event.

This is less efficient then calling the constructor once and the next
method often, but it does save typing sometimes.

=cut

for my $flavour (qw(idle var timer io signal)) {
   push @EXPORT, "do_$flavour";
   my $new = \&{"Event::$flavour"};
   my $class = "Coro::Event::$flavour";
   my $type = $flavour eq "io" ? 1 : 0;
   @{"${class}::ISA"} = (Coro::Event::, "Event::$flavour");
   my $coronew = sub {
      # how does one do method-call-by-name?
      # my $w = $class->SUPER::$flavour(@_);

      shift eq Coro::Event::
         or croak "event constructor \"Coro::Event->$flavour\" must be called as a static method";

      my $w = $new->($class,
         desc   => $flavour,
         @_,
         parked => 1,
      );

      _install_std_cb $w, $type;
      
      # reblessing due to Event being broken
      bless $w, $class
   };
   *{    $flavour } = $coronew;
   *{"do_$flavour"} = sub {
      unshift @_, Coro::Event::;
      @_ = &$coronew;
      &Coro::schedule while &_next;
      $_[0]->cancel;
      &_event
   };
}

# do schedule in perl to avoid forcing a stack allocation.
# this is about 10% slower, though.
sub next($) {
   &Coro::schedule while &_next;
   &_event
}

sub Coro::Event::Event::hits { $_[0][3] }
sub Coro::Event::Event::got  { $_[0][4] }

=item sweep

Similar to Event::one_event and Event::sweep: The idle task is called once
(this has the effect of jumping back into the Event loop once to serve new
events).

The reason this function exists is that you sometimes want to serve events
while doing other work. Calling C<Coro::cede> does not work because
C<cede> implies that the current coroutine is runnable and does not call
into the Event dispatcher.

=cut

sub sweep {
   Event::one_event 0; # for now
}

# very inefficient
our $IDLE = new Coro sub {
   while () {
      &Event::one_event;
      &Coro::schedule;
   }
};
$IDLE->{desc} = "[Event idle process]";

$Coro::idle = $IDLE;

1;

=back

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

Revision:	1.83
Committed:	Sat Jun 20 07:16:31 2009 UTC (14 years, 11 months ago) by root
Branch:	MAIN
Changes since 1.82:	+15 -28 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3	root	1.76	Coro::Event - do events the coro-way, with Event
4	root	1.1
5			=head1 SYNOPSIS
6
7			use Coro;
8			use Coro::Event;
9
10			sub keyboard : Coro {
11	pcg	1.21	my $w = Coro::Event->io(fd => \*STDIN, poll => 'r');
12	root	1.1	while() {
13			print "cmd> ";
14			my $ev = $w->next; my $cmd = <STDIN>;
15			unloop unless $cmd ne "";
16			print "data> ";
17			my $ev = $w->next; my $data = <STDIN>;
18			}
19			}
20
21	root	1.8	loop;
22	root	1.1
23	root	1.47	# wait for input on stdin for one second
24			Coro::Event::do_io (fd => \*STDIN, timeout => 1) & Event::Watcher::R
25			or die "no input received";
26
27	root	1.83	# use a separate thread for event processing, if impossible in main:
28	root	1.52	Coro::async { Event::loop };
29
30	root	1.1	=head1 DESCRIPTION
31
32			This module enables you to create programs using the powerful Event model
33			(and module), while retaining the linear style known from simple or
34			threaded programs.
35
36			This module provides a method and a function for every watcher type
37			(I<flavour>) (see L<Event>). The only difference between these and the
38			watcher constructors from Event is that you do not specify a callback
39			function - it will be managed by this module.
40
41	root	1.83	Your application should just create all necessary threads and then call
42			C<Event::loop>.
43	root	1.1
44	root	1.83	Please note that even programs or modules (such as L<Coro::Handle>) that
45			use "traditional" event-based/continuation style will run more efficient
46			with this module then when using only Event.
47	root	1.37
48	root	1.42	=head1 WARNING
49
50	root	1.83	Please note that Event does not support multithreading. That means that
51			you B<MUST NOT> block in an event callback. Again: In Event callbacks,
52			you I<must never ever> call a Coro function that blocks the current
53			thread.
54	root	1.42
55			While this seems to work superficially, it will eventually cause memory
56	root	1.52	corruption and often results in deadlocks.
57
58			Best practise is to always use B<Coro::unblock_sub> for your callbacks.
59	root	1.42
60	root	1.45	=head1 SEMANTICS
61
62	root	1.46	Whenever Event blocks (e.g. in a call to C<one_event>, C<loop> etc.),
63	root	1.83	this module cede's to all other threads with the same or higher
64			priority. When any threads of lower priority are ready, it will not
65	root	1.45	block but run one of them and then check for events.
66
67			The effect is that coroutines with the same or higher priority than
68			the blocking coroutine will keep Event from checking for events, while
69			coroutines with lower priority are being run, but Event checks for new
70	root	1.83	events after every cede. Note that for this to work you actually need to
71			run the event loop in some thread.
72	root	1.45
73	root	1.42	=head1 FUNCTIONS
74
75	root	1.1	=over 4
76
77			=cut
78
79			package Coro::Event;
80
81	root	1.42	no warnings;
82	root	1.1
83			use Carp;
84	root	1.30	no warnings;
85	root	1.1
86			use Coro;
87	root	1.83	use Event qw(loop unloop); # we are re-exporting this for historical reasons
88	root	1.1
89	root	1.30	use XSLoader;
90	root	1.1
91	root	1.30	use base Exporter::;
92
93	root	1.41	our @EXPORT = qw(loop unloop sweep);
94	root	1.1
95	root	1.2	BEGIN {
96	root	1.82	our $VERSION = 5.132;
97	root	1.2
98	root	1.13	local $^W = 0; # avoid redefine warning for Coro::ready;
99	root	1.30	XSLoader::load __PACKAGE__, $VERSION;
100	root	1.2	}
101	root	1.1
102	root	1.42	=item $w = Coro::Event->flavour (args...)
103	root	1.1
104			Create and return a watcher of the given type.
105
106			Examples:
107
108	root	1.77	my $reader = Coro::Event->io (fd => $filehandle, poll => 'r');
109	root	1.1	$reader->next;
110
111			=cut
112
113			=item $w->next
114
115	root	1.47	Wait for and return the next event of the event queue of the watcher. The
116			returned event objects support two methods only: C<hits> and C<got>, both
117			of which return integers: the number this watcher was hit for this event,
118			and the mask of poll events received.
119	root	1.1
120			=cut
121
122	root	1.42	=item do_flavour args...
123	root	1.1
124	root	1.47	Create a watcher of the given type and immediately call it's next method,
125			returning the event.
126
127			This is less efficient then calling the constructor once and the next
128			method often, but it does save typing sometimes.
129	root	1.1
130			=cut
131
132			for my $flavour (qw(idle var timer io signal)) {
133			push @EXPORT, "do_$flavour";
134			my $new = \&{"Event::$flavour"};
135			my $class = "Coro::Event::$flavour";
136	root	1.2	my $type = $flavour eq "io" ? 1 : 0;
137	root	1.1	@{"${class}::ISA"} = (Coro::Event::, "Event::$flavour");
138			my $coronew = sub {
139			# how does one do method-call-by-name?
140			# my $w = $class->SUPER::$flavour(@_);
141
142	root	1.10	shift eq Coro::Event::
143	root	1.1	or croak "event constructor \"Coro::Event->$flavour\" must be called as a static method";
144
145	root	1.10	my $w = $new->($class,
146	root	1.49	desc => $flavour,
147			@_,
148			parked => 1,
149	root	1.1	);
150	root	1.43
151			_install_std_cb $w, $type;
152
153			# reblessing due to Event being broken
154			bless $w, $class
155	root	1.1	};
156			*{ $flavour } = $coronew;
157			*{"do_$flavour"} = sub {
158			unshift @_, Coro::Event::;
159	root	1.50	@_ = &$coronew;
160			&Coro::schedule while &_next;
161	root	1.51	$_[0]->cancel;
162	root	1.50	&_event
163	root	1.1	};
164			}
165
166	root	1.50	# do schedule in perl to avoid forcing a stack allocation.
167			# this is about 10% slower, though.
168			sub next($) {
169			&Coro::schedule while &_next;
170			&_event
171			}
172
173	root	1.47	sub Coro::Event::Event::hits { $_[0][3] }
174			sub Coro::Event::Event::got { $_[0][4] }
175	root	1.1
176			=item sweep
177
178			Similar to Event::one_event and Event::sweep: The idle task is called once
179			(this has the effect of jumping back into the Event loop once to serve new
180			events).
181
182			The reason this function exists is that you sometimes want to serve events
183			while doing other work. Calling C<Coro::cede> does not work because
184			C<cede> implies that the current coroutine is runnable and does not call
185			into the Event dispatcher.
186
187			=cut
188
189			sub sweep {
190	root	1.42	Event::one_event 0; # for now
191	root	1.1	}
192
193	root	1.52	# very inefficient
194	root	1.77	our $IDLE = new Coro sub {
195	root	1.52	while () {
196			&Event::one_event;
197			&Coro::schedule;
198			}
199			};
200	root	1.77	$IDLE->{desc} = "[Event idle process]";
201	root	1.52
202	root	1.77	$Coro::idle = $IDLE;
203	root	1.9
204	root	1.1	1;
205
206	root	1.36	=back
207
208	root	1.1	=head1 AUTHOR
209
210	root	1.27	Marc Lehmann <schmorp@schmorp.de>
211	root	1.25	http://home.schmorp.de/
212	root	1.1
213			=cut
214