EV-Loop-Async/Async.pm

=head1 NAME

EV::Loop::Async - run an EV event loop asynchronously

=head1 SYNOPSIS

  use EV::Loop::Async;
  
  my $loop = EV::Loop::Async::default;
  my $timer;
  my $flag;
  
  {
     $loop->scope_lock; # lock the loop structures
     $timer = $loop->timer (5, 1, sub { $flag = 1 });
     $loop->nudge; # tell loop to take note of the timer
  }
  
  1 while $flag; # $flag will be set asynchronously
  
  {
     $loop->interrupt->scope_block;
     # critical section, no watcher callback interruptions
  }
  
  # stop timer again
  
  {
     $loop->scope_lock; # lock the loop structures
     $timer->stop;
     # no need to nudge
  }

=head1 DESCRIPTION

This module implements a rather specialised event loop - it takes a normal
L<EV> event loop and runs it in a separate thread. That means it will poll
for events even while your foreground Perl interpreter is busy (you don't
need to have perls pseudo-threads enabled for this either).

Whenever the event loop detecs new events, it will interrupt perl and ask
it to invoke all the pending watcher callbacks. This invocation will be
"synchronous" (in the perl thread), but it can happen at any time.

See the documentation for L<Async::Interrupt> for details on when and how
your perl program can be interrupted (and how to avoid it), and how to
integrate background event loops into foreground ones.

=head1 FAQ

=head1 FUNCTIONS, METHODS AND VARIABLES OF THIS MODULE

=over 4

=cut

package EV::Loop::Async;

use common::sense;

use EV ();
use Async::Interrupt ();

use base 'EV::Loop';

BEGIN {
   our $VERSION = '0.02';

   require XSLoader;
   XSLoader::load ("EV::Loop::Async", $VERSION);
}

=item $loop = EV::Loop::Async::default

Return the default loop, usable by all programs. The default loop will be
created on the first call to C<default> by calling X<new EV::Loop>, and
should be used by all programs unless they have special requirements.

The associated L<Async::Interrupt> object is stored in
C<$EV::Loop::Async::AI>, and can be used to lock critical sections etc.

=cut

our ($LOOP, $INTERRUPT);

sub default() {
   $LOOP || do {
      $LOOP      = new EV::Loop::Async;
      $INTERRUPT = $LOOP->interrupt;

      $LOOP
   }
}

=item $EV::Loop::Async::LOOP

The default async loop, available after the first call to
C<EV::Loop::Async::default>.

=item $EV::Loop::Async::INTERRUPT

The default loop's L<Async::Interrupt> object, for easy access.

Example: create a section of code where no callback invocations will
interrupt:

   {
      $EV::Loop::Async::INTERRUPT->scope_block;
      # no default loop callbacks will be executed here.
      # the loop will not be locked, however.
   }

=item $loop = new EV::Loop::Async $flags, [Async-Interrupt-Arguments...]

This constructor:

=over 4

=item 1. creates a new C<EV::Loop> (similar C<new EV::Loop>).

=item 2. creates a new L<Async::Interrupt> object and attaches itself to it.

=item 3. creates a new background thread.

=item 4. runs C<< $loop->run >> in that thread.

=back

The resulting loop will be running and unlocked when it is returned.

=cut

sub new {
   my ($class, $flags, @asy) = @_;

   my $self = bless $class->SUPER::new ($flags), $class;
   my ($c_func, $c_arg) = _c_func $self;
   my $asy = new Async::Interrupt @asy, c_cb => [$c_func, $c_arg];
   $self->_attach ($asy, $asy->signal_func);

   $self
}

=item $loop->nudge

Wake up the asynchronous loop. This is useful after registering a new
watcher, to ensure that the background event loop integrates the new
watcher(s) (which only happens when it iterates, which you can force by
calling this method).

Without calling this method, the event loop I<eventually> takes notice
of new watchers, bit when this happens is not wlel-defined (can be
instantaneous, or take a few hours).

No locking is required.

Example: lock the loop, create a timer, nudge the loop so it takes notice
of the new timer, then evily busy-wait till the timer fires.

   my $timer;
   my $flag;

   {
      $loop->scope_lock;
      $timer = $loop->timer (1, 0, sub { $flag = 1 });
      $loop->nudge;
   }

   1 until $flag;

=item $loop->lock

=item $loop->unlock

Lock/unlock the loop data structures. Since the event loop runs in
a separate thread, you have to lock the loop data structures before
accessing them in any way. Since I was lazy, you have to do this manually.

You must lock under the same conditions as you would have to lock the
underlying C library, e.g. when starting or stopping watchers (but not
when creating or destroying them, but note that create and destroy often
starts and stops for you, in which case you have to lock).

When in doubt, lock.

See also the next method, C<< $loop->scope_lock >> for a more failsafe way
to lock parts of your code.

Note that there must be exactly one call of "unblock" for every previous
call to "block" (i.e. calls can nest).

=item $loop->scope_lock

Calls C<lock> immediately, and C<unlock> automatically whent he current
scope is left.

=back

=head1 SEE ALSO

L<EV>, L<Async::Interrupt>.

=head1 AUTHOR

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

=cut

1

Revision:	1.2
Committed:	Tue Jul 14 13:24:34 2009 UTC (14 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.1:	+98 -10 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	EV::Loop::Async - run an EV event loop asynchronously
4
5	=head1 SYNOPSIS
6
7	use EV::Loop::Async;
8
9	my $loop = EV::Loop::Async::default;
10	my $timer;
11	my $flag;
12
13	{
14	$loop->scope_lock; # lock the loop structures
15	$timer = $loop->timer (5, 1, sub { $flag = 1 });
16	$loop->nudge; # tell loop to take note of the timer
17	}
18
19	1 while $flag; # $flag will be set asynchronously
20
21	{
22	$loop->interrupt->scope_block;
23	# critical section, no watcher callback interruptions
24	}
25
26	# stop timer again
27
28	{
29	$loop->scope_lock; # lock the loop structures
30	$timer->stop;
31	# no need to nudge
32	}
33
34	=head1 DESCRIPTION
35
36	This module implements a rather specialised event loop - it takes a normal
37	L<EV> event loop and runs it in a separate thread. That means it will poll
38	for events even while your foreground Perl interpreter is busy (you don't
39	need to have perls pseudo-threads enabled for this either).
40
41	Whenever the event loop detecs new events, it will interrupt perl and ask
42	it to invoke all the pending watcher callbacks. This invocation will be
43	"synchronous" (in the perl thread), but it can happen at any time.
44
45	See the documentation for L<Async::Interrupt> for details on when and how
46	your perl program can be interrupted (and how to avoid it), and how to
47	integrate background event loops into foreground ones.
48
49	=head1 FAQ
50
51	=head1 FUNCTIONS, METHODS AND VARIABLES OF THIS MODULE
52
53	=over 4
54
55	=cut
56
57	package EV::Loop::Async;
58
59	use common::sense;
60
61	use EV ();
62	use Async::Interrupt ();
63
64	use base 'EV::Loop';
65
66	BEGIN {
67	our $VERSION = '0.02';
68
69	require XSLoader;
70	XSLoader::load ("EV::Loop::Async", $VERSION);
71	}
72
73	=item $loop = EV::Loop::Async::default
74
75	Return the default loop, usable by all programs. The default loop will be
76	created on the first call to C<default> by calling X<new EV::Loop>, and
77	should be used by all programs unless they have special requirements.
78
79	The associated L<Async::Interrupt> object is stored in
80	C<$EV::Loop::Async::AI>, and can be used to lock critical sections etc.
81
82	=cut
83
84	our ($LOOP, $INTERRUPT);
85
86	sub default() {
87	$LOOP \|\| do {
88	$LOOP = new EV::Loop::Async;
89	$INTERRUPT = $LOOP->interrupt;
90
91	$LOOP
92	}
93	}
94
95	=item $EV::Loop::Async::LOOP
96
97	The default async loop, available after the first call to
98	C<EV::Loop::Async::default>.
99
100	=item $EV::Loop::Async::INTERRUPT
101
102	The default loop's L<Async::Interrupt> object, for easy access.
103
104	Example: create a section of code where no callback invocations will
105	interrupt:
106
107	{
108	$EV::Loop::Async::INTERRUPT->scope_block;
109	# no default loop callbacks will be executed here.
110	# the loop will not be locked, however.
111	}
112
113	=item $loop = new EV::Loop::Async $flags, [Async-Interrupt-Arguments...]
114
115	This constructor:
116
117	=over 4
118
119	=item 1. creates a new C<EV::Loop> (similar C<new EV::Loop>).
120
121	=item 2. creates a new L<Async::Interrupt> object and attaches itself to it.
122
123	=item 3. creates a new background thread.
124
125	=item 4. runs C<< $loop->run >> in that thread.
126
127	=back
128
129	The resulting loop will be running and unlocked when it is returned.
130
131	=cut
132
133	sub new {
134	my ($class, $flags, @asy) = @_;
135
136	my $self = bless $class->SUPER::new ($flags), $class;
137	my ($c_func, $c_arg) = _c_func $self;
138	my $asy = new Async::Interrupt @asy, c_cb => [$c_func, $c_arg];
139	$self->_attach ($asy, $asy->signal_func);
140
141	$self
142	}
143
144	=item $loop->nudge
145
146	Wake up the asynchronous loop. This is useful after registering a new
147	watcher, to ensure that the background event loop integrates the new
148	watcher(s) (which only happens when it iterates, which you can force by
149	calling this method).
150
151	Without calling this method, the event loop I<eventually> takes notice
152	of new watchers, bit when this happens is not wlel-defined (can be
153	instantaneous, or take a few hours).
154
155	No locking is required.
156
157	Example: lock the loop, create a timer, nudge the loop so it takes notice
158	of the new timer, then evily busy-wait till the timer fires.
159
160	my $timer;
161	my $flag;
162
163	{
164	$loop->scope_lock;
165	$timer = $loop->timer (1, 0, sub { $flag = 1 });
166	$loop->nudge;
167	}
168
169	1 until $flag;
170
171	=item $loop->lock
172
173	=item $loop->unlock
174
175	Lock/unlock the loop data structures. Since the event loop runs in
176	a separate thread, you have to lock the loop data structures before
177	accessing them in any way. Since I was lazy, you have to do this manually.
178
179	You must lock under the same conditions as you would have to lock the
180	underlying C library, e.g. when starting or stopping watchers (but not
181	when creating or destroying them, but note that create and destroy often
182	starts and stops for you, in which case you have to lock).
183
184	When in doubt, lock.
185
186	See also the next method, C<< $loop->scope_lock >> for a more failsafe way
187	to lock parts of your code.
188
189	Note that there must be exactly one call of "unblock" for every previous
190	call to "block" (i.e. calls can nest).
191
192	=item $loop->scope_lock
193
194	Calls C<lock> immediately, and C<unlock> automatically whent he current
195	scope is left.
196
197	=back
198
199	=head1 SEE ALSO
200
201	L<EV>, L<Async::Interrupt>.
202
203	=head1 AUTHOR
204
205	Marc Lehmann <schmorp@schmorp.de>
206	http://home.schmorp.de/
207
208	=cut
209
210	1
211