Coro/Event/Event.pm

=head1 NAME

Coro::Event - do events the coro-way

=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 coroutine 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 coroutines and then call
Coro::Event::loop.

Please note that even programs or modules (such as
L<Coro::Handle|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 coroutines or threads. That
means that you B<MUST NOT> block in an event callback. Again: In Event
callbacks, you I<must never ever> call a Coroutine function that blocks
the current coroutine.

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 coroutines with the same or higher
priority. When any coroutines 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.

=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, cooool!

use XSLoader;

use base Exporter::;

our @EXPORT = qw(loop unloop sweep);

BEGIN {
   our $VERSION = 4.74;

   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
}

=item $result = loop([$timeout])

This is the version of C<loop> you should use instead of C<Event::loop>
when using this module - it will ensure correct scheduling in the presence
of events.

=item unloop([$result])

Same as Event::unloop (provided here for your convinience only).

=cut

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

$Coro::idle = sub { $event_idle->ready };

1;

=back

=head1 AUTHOR

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

=cut

Revision:	1.58
Committed:	Thu May 29 18:05:53 2008 UTC (16 years ago) by root
Branch:	MAIN
CVS Tags:	rel-4_74
Changes since 1.57:	+1 -1 lines
Log Message:	4.74
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			Coro::Event - do events the coro-way
4
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
25			Coro::Event::do_io (fd => \*STDIN, timeout => 1) & Event::Watcher::R
26			or die "no input received";
27
28	root	1.52	# use a separate coroutine for event processing, if impossible in main:
29			Coro::async { Event::loop };
30
31	root	1.1	=head1 DESCRIPTION
32
33			This module enables you to create programs using the powerful Event model
34			(and module), while retaining the linear style known from simple or
35			threaded programs.
36
37			This module provides a method and a function for every watcher type
38			(I<flavour>) (see L<Event>). The only difference between these and the
39			watcher constructors from Event is that you do not specify a callback
40			function - it will be managed by this module.
41
42			Your application should just create all necessary coroutines and then call
43	root	1.12	Coro::Event::loop.
44	root	1.1
45	root	1.37	Please note that even programs or modules (such as
46			L<Coro::Handle\|Coro::Handle>) that use "traditional"
47			event-based/continuation style will run more efficient with this module
48			then when using only Event.
49
50	root	1.42	=head1 WARNING
51
52			Please note that Event does not support coroutines or threads. That
53			means that you B<MUST NOT> block in an event callback. Again: In Event
54	root	1.52	callbacks, you I<must never ever> call a Coroutine function that blocks
55	root	1.42	the current coroutine.
56
57			While this seems to work superficially, it will eventually cause memory
58	root	1.52	corruption and often results in deadlocks.
59
60			Best practise is to always use B<Coro::unblock_sub> for your callbacks.
61	root	1.42
62	root	1.45	=head1 SEMANTICS
63
64	root	1.46	Whenever Event blocks (e.g. in a call to C<one_event>, C<loop> etc.),
65	root	1.45	this module cede's to all other coroutines with the same or higher
66			priority. When any coroutines of lower priority are ready, it will not
67			block but run one of them and then check for events.
68
69			The effect is that coroutines with the same or higher priority than
70			the blocking coroutine will keep Event from checking for events, while
71			coroutines with lower priority are being run, but Event checks for new
72			events after every cede.
73
74	root	1.42	=head1 FUNCTIONS
75
76	root	1.1	=over 4
77
78			=cut
79
80			package Coro::Event;
81
82	root	1.42	no warnings;
83	root	1.1
84			use Carp;
85	root	1.30	no warnings;
86	root	1.1
87			use Coro;
88	root	1.8	use Event qw(loop unloop); # we are re-exporting this, cooool!
89	root	1.1
90	root	1.30	use XSLoader;
91	root	1.1
92	root	1.30	use base Exporter::;
93
94	root	1.41	our @EXPORT = qw(loop unloop sweep);
95	root	1.1
96	root	1.2	BEGIN {
97	root	1.58	our $VERSION = 4.74;
98	root	1.2
99	root	1.13	local $^W = 0; # avoid redefine warning for Coro::ready;
100	root	1.30	XSLoader::load __PACKAGE__, $VERSION;
101	root	1.2	}
102	root	1.1
103	root	1.42	=item $w = Coro::Event->flavour (args...)
104	root	1.1
105			Create and return a watcher of the given type.
106
107			Examples:
108
109			my $reader = Coro::Event->io(fd => $filehandle, poll => 'r');
110			$reader->next;
111
112			=cut
113
114			=item $w->next
115
116	root	1.47	Wait for and return the next event of the event queue of the watcher. The
117			returned event objects support two methods only: C<hits> and C<got>, both
118			of which return integers: the number this watcher was hit for this event,
119			and the mask of poll events received.
120	root	1.1
121			=cut
122
123	root	1.42	=item do_flavour args...
124	root	1.1
125	root	1.47	Create a watcher of the given type and immediately call it's next method,
126			returning the event.
127
128			This is less efficient then calling the constructor once and the next
129			method often, but it does save typing sometimes.
130	root	1.1
131			=cut
132
133			for my $flavour (qw(idle var timer io signal)) {
134			push @EXPORT, "do_$flavour";
135			my $new = \&{"Event::$flavour"};
136			my $class = "Coro::Event::$flavour";
137	root	1.2	my $type = $flavour eq "io" ? 1 : 0;
138	root	1.1	@{"${class}::ISA"} = (Coro::Event::, "Event::$flavour");
139			my $coronew = sub {
140			# how does one do method-call-by-name?
141			# my $w = $class->SUPER::$flavour(@_);
142
143	root	1.10	shift eq Coro::Event::
144	root	1.1	or croak "event constructor \"Coro::Event->$flavour\" must be called as a static method";
145
146	root	1.10	my $w = $new->($class,
147	root	1.49	desc => $flavour,
148			@_,
149			parked => 1,
150	root	1.1	);
151	root	1.43
152			_install_std_cb $w, $type;
153
154			# reblessing due to Event being broken
155			bless $w, $class
156	root	1.1	};
157			*{ $flavour } = $coronew;
158			*{"do_$flavour"} = sub {
159			unshift @_, Coro::Event::;
160	root	1.50	@_ = &$coronew;
161			&Coro::schedule while &_next;
162	root	1.51	$_[0]->cancel;
163	root	1.50	&_event
164	root	1.1	};
165			}
166
167	root	1.50	# do schedule in perl to avoid forcing a stack allocation.
168			# this is about 10% slower, though.
169			sub next($) {
170			&Coro::schedule while &_next;
171			&_event
172			}
173
174	root	1.47	sub Coro::Event::Event::hits { $_[0][3] }
175			sub Coro::Event::Event::got { $_[0][4] }
176	root	1.1
177			=item sweep
178
179			Similar to Event::one_event and Event::sweep: The idle task is called once
180			(this has the effect of jumping back into the Event loop once to serve new
181			events).
182
183			The reason this function exists is that you sometimes want to serve events
184			while doing other work. Calling C<Coro::cede> does not work because
185			C<cede> implies that the current coroutine is runnable and does not call
186			into the Event dispatcher.
187
188			=cut
189
190			sub sweep {
191	root	1.42	Event::one_event 0; # for now
192	root	1.1	}
193
194			=item $result = loop([$timeout])
195
196			This is the version of C<loop> you should use instead of C<Event::loop>
197			when using this module - it will ensure correct scheduling in the presence
198			of events.
199
200			=item unloop([$result])
201
202			Same as Event::unloop (provided here for your convinience only).
203
204			=cut
205
206	root	1.52	# very inefficient
207			our $event_idle = new Coro sub {
208			while () {
209			&Event::one_event;
210			&Coro::schedule;
211			}
212			};
213	root	1.53	$event_idle->{desc} = "[Event idle process]";
214	root	1.52
215			$Coro::idle = sub { $event_idle->ready };
216	root	1.9
217	root	1.1	1;
218
219	root	1.36	=back
220
221	root	1.1	=head1 AUTHOR
222
223	root	1.27	Marc Lehmann <schmorp@schmorp.de>
224	root	1.25	http://home.schmorp.de/
225	root	1.1
226			=cut
227