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;

use common::sense;

use Carp;

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 = 6.57;

   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 its 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 if Coro::nready;
   }
};
$IDLE->{desc} = "[Event idle thread]";

$Coro::idle = $IDLE;

1;

=back

=head1 AUTHOR/SUPPORT/CONTACT

   Marc A. Lehmann <schmorp@schmorp.de>
   http://software.schmorp.de/pkg/Coro.html

=cut

Revision:	1.147
Committed:	Mon Mar 16 11:12:53 2020 UTC (5 years, 8 months ago) by root
Branch:	MAIN
CVS Tags:	rel-6_57, HEAD
Changes since 1.146:	+1 -1 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	Coro::Event - do events the coro-way, with Event
4
5	=head1 SYNOPSIS
6
7	use Coro;
8	use Coro::Event;
9
10	sub keyboard : Coro {
11	my $w = Coro::Event->io(fd => \*STDIN, poll => 'r');
12	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	loop;
22
23	# 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	# use a separate thread for event processing, if impossible in main:
28	Coro::async { Event::loop };
29
30	=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	Your application should just create all necessary threads and then call
42	C<Event::loop>.
43
44	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
48	=head1 WARNING
49
50	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
55	While this seems to work superficially, it will eventually cause memory
56	corruption and often results in deadlocks.
57
58	Best practise is to always use B<Coro::unblock_sub> for your callbacks.
59
60	=head1 SEMANTICS
61
62	Whenever Event blocks (e.g. in a call to C<one_event>, C<loop> etc.),
63	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	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	events after every cede. Note that for this to work you actually need to
71	run the event loop in some thread.
72
73	=head1 FUNCTIONS
74
75	=over 4
76
77	=cut
78
79	package Coro::Event;
80
81	use common::sense;
82
83	use Carp;
84
85	use Coro;
86	use Event qw(loop unloop); # we are re-exporting this for historical reasons
87
88	use XSLoader;
89
90	use base Exporter::;
91
92	our @EXPORT = qw(loop unloop sweep);
93
94	BEGIN {
95	our $VERSION = 6.57;
96
97	local $^W = 0; # avoid redefine warning for Coro::ready;
98	XSLoader::load __PACKAGE__, $VERSION;
99	}
100
101	=item $w = Coro::Event->flavour (args...)
102
103	Create and return a watcher of the given type.
104
105	Examples:
106
107	my $reader = Coro::Event->io (fd => $filehandle, poll => 'r');
108	$reader->next;
109
110	=cut
111
112	=item $w->next
113
114	Wait for and return the next event of the event queue of the watcher. The
115	returned event objects support two methods only: C<hits> and C<got>, both
116	of which return integers: the number this watcher was hit for this event,
117	and the mask of poll events received.
118
119	=cut
120
121	=item do_flavour args...
122
123	Create a watcher of the given type and immediately call its next method,
124	returning the event.
125
126	This is less efficient then calling the constructor once and the next
127	method often, but it does save typing sometimes.
128
129	=cut
130
131	for my $flavour (qw(idle var timer io signal)) {
132	push @EXPORT, "do_$flavour";
133	my $new = \&{"Event::$flavour"};
134	my $class = "Coro::Event::$flavour";
135	my $type = $flavour eq "io" ? 1 : 0;
136	@{"${class}::ISA"} = (Coro::Event::, "Event::$flavour");
137	my $coronew = sub {
138	# how does one do method-call-by-name?
139	# my $w = $class->SUPER::$flavour(@_);
140
141	shift eq Coro::Event::
142	or croak "event constructor \"Coro::Event->$flavour\" must be called as a static method";
143
144	my $w = $new->($class,
145	desc => $flavour,
146	@_,
147	parked => 1,
148	);
149
150	_install_std_cb $w, $type;
151
152	# reblessing due to Event being broken
153	bless $w, $class
154	};
155	*{ $flavour } = $coronew;
156	*{"do_$flavour"} = sub {
157	unshift @_, Coro::Event::;
158	@_ = &$coronew;
159	&Coro::schedule while &_next;
160	$_[0]->cancel;
161	&_event
162	};
163	}
164
165	# do schedule in perl to avoid forcing a stack allocation.
166	# this is about 10% slower, though.
167	sub next($) {
168	&Coro::schedule while &_next;
169	&_event
170	}
171
172	sub Coro::Event::Event::hits { $_[0][3] }
173	sub Coro::Event::Event::got { $_[0][4] }
174
175	=item sweep
176
177	Similar to Event::one_event and Event::sweep: The idle task is called once
178	(this has the effect of jumping back into the Event loop once to serve new
179	events).
180
181	The reason this function exists is that you sometimes want to serve events
182	while doing other work. Calling C<Coro::cede> does not work because
183	C<cede> implies that the current coroutine is runnable and does not call
184	into the Event dispatcher.
185
186	=cut
187
188	sub sweep {
189	Event::one_event 0; # for now
190	}
191
192	# very inefficient
193	our $IDLE = new Coro sub {
194	while () {
195	Event::one_event;
196	Coro::schedule if Coro::nready;
197	}
198	};
199	$IDLE->{desc} = "[Event idle thread]";
200
201	$Coro::idle = $IDLE;
202
203	1;
204
205	=back
206
207	=head1 AUTHOR/SUPPORT/CONTACT
208
209	Marc A. Lehmann <schmorp@schmorp.de>
210	http://software.schmorp.de/pkg/Coro.html
211
212	=cut
213