Coro/Coro/Util.pm

=head1 NAME

Coro::Util - various utility functions.

=head1 SYNOPSIS

 use Coro::Util;

=head1 DESCRIPTION

This module implements various utility functions, mostly replacing perl
functions by non-blocking counterparts.

This module is an AnyEvent user. Refer to the L<AnyEvent|AnyEvent>
documentation to see how to integrate it into your own programs.

=over 4

=cut

package Coro::Util;

use strict;

no warnings "uninitialized";

use AnyEvent;

use Coro::State;
use Coro::Handle;
use Coro::Storable ();
use Coro::Semaphore;

use base 'Exporter';

our @EXPORT = qw(gethostbyname gethostbyaddr);
our @EXPORT_OK = qw(inet_aton fork_eval);

our $VERSION = 2.0;

our $MAXPARALLEL = 16; # max. number of parallel jobs

my $jobs = new Coro::Semaphore $MAXPARALLEL;

sub _do_asy(&;@) {
   my $sub = shift;
   $jobs->down;
   my $fh;

   my $pid = open $fh, "-|";

   if (!defined $pid) {
      die "fork: $!";
   } elsif (!$pid) {
      syswrite STDOUT, join "\0", map { unpack "H*", $_ } &$sub;
      Coro::State::_exit 0;
   }

   my $buf;
   my $current = $Coro::current;
   my $w; $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub {
      sysread $fh, $buf, 16384, length $buf
         and return;

      undef $w;
      $current->ready;
   });

   &Coro::schedule;
   &Coro::schedule while $w;

   $jobs->up;
   my @r = map { pack "H*", $_ } split /\0/, $buf;
   wantarray ? @r : $r[0];
}

sub dotted_quad($) {
   $_[0] =~ /^(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9][0-9]?)
            \.(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9][0-9]?)
            \.(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9][0-9]?)
            \.(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9][0-9]?)$/x
}

=item gethostbyname, gethostbyaddr

Work exactly like their perl counterparts, but do not block. Currently
this is being implemented with forking, so it's not exactly low-cost.

=cut

my $netdns = eval { die; require Net::DNS::Resolver; new Net::DNS::Resolver; };

sub gethostbyname($) {
   if ($netdns) {
      #$netdns->query($_[0]);
      die;
   } else {
      _do_asy { gethostbyname $_[0] } @_
   }
}

sub gethostbyaddr($$) {
   if ($netdns) {
      die;
   } else {
      _do_asy { gethostbyaddr $_[0], $_[1] } @_
   }
}

=item Coro::Util::inet_aton

Works almost exactly like its Socket counterpart, except that it does not
block. Is implemented with forking, so not exactly low-cost.

=cut

use Socket;

our $inet_aton = \&Socket::inet_aton;

sub inet_aton {
   require Socket;

   if (dotted_quad $_[0]) {
      $inet_aton->($_[0])
   } else {
      _do_asy { $inet_aton->($_[0]) } @_
   }
}

=item @result = Coro::Util::fork_eval { ... }, @args

Executes the given code block or code reference with the given arguments
in a separate process, returning the results. The return values must be
serialisable with Coro::Storable. It may, of course, block.

Note that using event handling in the sub is not usually a good idea as
you will inherit a mixed set of watchers from the parent.

Exceptions will be correctly forwarded to the caller.

This function is useful for pushing cpu-intensive computations into a
different process, for example to take advantage of multiple CPU's. Its
also useful if you want to simply run some blocking functions (such as
C<system()>) and do not care about the overhead enough to code your own
pid watcher etc.

This function might keep a pool of processes in some future version, as
fork can be rather slow in large processes.

Example: execute some external program (convert image to rgba raw form)
and add a long computation (extract the alpha channel) in a separate
process, making sure that never more then $NUMCPUS processes are being
run.

   my $cpulock = new Coro::Semaphore $NUMCPUS;

   sub do_it {
      my ($path) = @_;

      my $guard = $cpulock->guard;

      Coro::Util::fork_eval {
         open my $fh, "convert -depth 8 \Q$path\E rgba:"
            or die "$path: $!";

         local $/;
         # make my eyes hurt
         pack "C*", unpack "(xxxC)*", <$fh>
      }
   }

   my $alphachannel = do_it "/tmp/img.png";

=cut

sub fork_eval(&@) {
   my ($cb, @args) = @_;

   pipe my $fh1, my $fh2
      or die "pipe: $!";

   my $pid = fork;

   if ($pid) {
      undef $fh2;

      my $res = Coro::Storable::thaw +(Coro::Handle::unblock $fh1)->readline (undef);
      waitpid $pid, 0; # should not block, we expect the child to simply behave

      die $$res unless "ARRAY" eq ref $res;

      return wantarray ? @$res : $res->[-1];

   } elsif (defined $pid) {
      delete $SIG{__WARN__};
      delete $SIG{__DIE__};
      # just in case, this hack effectively disables event processing
      # in the child. cleaner and slower would be to canceling all
      # event watchers, but we are event-model agnostic.
      undef $Coro::idle;
      $Coro::current->prio (Coro::PRIO_MAX);

      eval {
         undef $fh1;

         my @res = eval { $cb->(@args) };

         open my $fh, ">", \my $buf
            or die "fork_eval: cannot open fh-to-buf in child: $!";
         Storable::store_fd $@ ? \"$@" : \@res, $fh;
         close $fh;

         syswrite $fh2, $buf;
         close $fh2;
      };

      warn $@ if $@;
      Coro::State::_exit 0;

   } else {
      die "fork_eval: $!";
   }
}

1;

=back

=head1 AUTHOR

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

=cut

Revision:	1.13
Committed:	Sat Oct 27 14:07:31 2007 UTC (16 years, 7 months ago) by root
Branch:	MAIN
Changes since 1.12:	+0 -1 lines
Log Message:	* empty log message *
#	Content
1	=head1 NAME
2
3	Coro::Util - various utility functions.
4
5	=head1 SYNOPSIS
6
7	use Coro::Util;
8
9	=head1 DESCRIPTION
10
11	This module implements various utility functions, mostly replacing perl
12	functions by non-blocking counterparts.
13
14	This module is an AnyEvent user. Refer to the L<AnyEvent\|AnyEvent>
15	documentation to see how to integrate it into your own programs.
16
17	=over 4
18
19	=cut
20
21	package Coro::Util;
22
23	use strict;
24
25	no warnings "uninitialized";
26
27	use AnyEvent;
28
29	use Coro::State;
30	use Coro::Handle;
31	use Coro::Storable ();
32	use Coro::Semaphore;
33
34	use base 'Exporter';
35
36	our @EXPORT = qw(gethostbyname gethostbyaddr);
37	our @EXPORT_OK = qw(inet_aton fork_eval);
38
39	our $VERSION = 2.0;
40
41	our $MAXPARALLEL = 16; # max. number of parallel jobs
42
43	my $jobs = new Coro::Semaphore $MAXPARALLEL;
44
45	sub _do_asy(&;@) {
46	my $sub = shift;
47	$jobs->down;
48	my $fh;
49
50	my $pid = open $fh, "-\|";
51
52	if (!defined $pid) {
53	die "fork: $!";
54	} elsif (!$pid) {
55	syswrite STDOUT, join "\0", map { unpack "H*", $_ } &$sub;
56	Coro::State::_exit 0;
57	}
58
59	my $buf;
60	my $current = $Coro::current;
61	my $w; $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub {
62	sysread $fh, $buf, 16384, length $buf
63	and return;
64
65	undef $w;
66	$current->ready;
67	});
68
69	&Coro::schedule;
70	&Coro::schedule while $w;
71
72	$jobs->up;
73	my @r = map { pack "H*", $_ } split /\0/, $buf;
74	wantarray ? @r : $r[0];
75	}
76
77	sub dotted_quad($) {
78	$_[0] =~ /^(?:25[0-5]\|2[0-4][0-9]\|1[0-9][0-9]\|[0-9][0-9]?)
79	\.(?:25[0-5]\|2[0-4][0-9]\|1[0-9][0-9]\|[0-9][0-9]?)
80	\.(?:25[0-5]\|2[0-4][0-9]\|1[0-9][0-9]\|[0-9][0-9]?)
81	\.(?:25[0-5]\|2[0-4][0-9]\|1[0-9][0-9]\|[0-9][0-9]?)$/x
82	}
83
84	=item gethostbyname, gethostbyaddr
85
86	Work exactly like their perl counterparts, but do not block. Currently
87	this is being implemented with forking, so it's not exactly low-cost.
88
89	=cut
90
91	my $netdns = eval { die; require Net::DNS::Resolver; new Net::DNS::Resolver; };
92
93	sub gethostbyname($) {
94	if ($netdns) {
95	#$netdns->query($_[0]);
96	die;
97	} else {
98	_do_asy { gethostbyname $_[0] } @_
99	}
100	}
101
102	sub gethostbyaddr($$) {
103	if ($netdns) {
104	die;
105	} else {
106	_do_asy { gethostbyaddr $_[0], $_[1] } @_
107	}
108	}
109
110	=item Coro::Util::inet_aton
111
112	Works almost exactly like its Socket counterpart, except that it does not
113	block. Is implemented with forking, so not exactly low-cost.
114
115	=cut
116
117	use Socket;
118
119	our $inet_aton = \&Socket::inet_aton;
120
121	sub inet_aton {
122	require Socket;
123
124	if (dotted_quad $_[0]) {
125	$inet_aton->($_[0])
126	} else {
127	_do_asy { $inet_aton->($_[0]) } @_
128	}
129	}
130
131	=item @result = Coro::Util::fork_eval { ... }, @args
132
133	Executes the given code block or code reference with the given arguments
134	in a separate process, returning the results. The return values must be
135	serialisable with Coro::Storable. It may, of course, block.
136
137	Note that using event handling in the sub is not usually a good idea as
138	you will inherit a mixed set of watchers from the parent.
139
140	Exceptions will be correctly forwarded to the caller.
141
142	This function is useful for pushing cpu-intensive computations into a
143	different process, for example to take advantage of multiple CPU's. Its
144	also useful if you want to simply run some blocking functions (such as
145	C<system()>) and do not care about the overhead enough to code your own
146	pid watcher etc.
147
148	This function might keep a pool of processes in some future version, as
149	fork can be rather slow in large processes.
150
151	Example: execute some external program (convert image to rgba raw form)
152	and add a long computation (extract the alpha channel) in a separate
153	process, making sure that never more then $NUMCPUS processes are being
154	run.
155
156	my $cpulock = new Coro::Semaphore $NUMCPUS;
157
158	sub do_it {
159	my ($path) = @_;
160
161	my $guard = $cpulock->guard;
162
163	Coro::Util::fork_eval {
164	open my $fh, "convert -depth 8 \Q$path\E rgba:"
165	or die "$path: $!";
166
167	local $/;
168	# make my eyes hurt
169	pack "C", unpack "(xxxC)", <$fh>
170	}
171	}
172
173	my $alphachannel = do_it "/tmp/img.png";
174
175	=cut
176
177	sub fork_eval(&@) {
178	my ($cb, @args) = @_;
179
180	pipe my $fh1, my $fh2
181	or die "pipe: $!";
182
183	my $pid = fork;
184
185	if ($pid) {
186	undef $fh2;
187
188	my $res = Coro::Storable::thaw +(Coro::Handle::unblock $fh1)->readline (undef);
189	waitpid $pid, 0; # should not block, we expect the child to simply behave
190
191	die $$res unless "ARRAY" eq ref $res;
192
193	return wantarray ? @$res : $res->[-1];
194
195	} elsif (defined $pid) {
196	delete $SIG{__WARN__};
197	delete $SIG{__DIE__};
198	# just in case, this hack effectively disables event processing
199	# in the child. cleaner and slower would be to canceling all
200	# event watchers, but we are event-model agnostic.
201	undef $Coro::idle;
202	$Coro::current->prio (Coro::PRIO_MAX);
203
204	eval {
205	undef $fh1;
206
207	my @res = eval { $cb->(@args) };
208
209	open my $fh, ">", \my $buf
210	or die "fork_eval: cannot open fh-to-buf in child: $!";
211	Storable::store_fd $@ ? \"$@" : \@res, $fh;
212	close $fh;
213
214	syswrite $fh2, $buf;
215	close $fh2;
216	};
217
218	warn $@ if $@;
219	Coro::State::_exit 0;
220
221	} else {
222	die "fork_eval: $!";
223	}
224	}
225
226	1;
227
228	=back
229
230	=head1 AUTHOR
231
232	Marc Lehmann <schmorp@schmorp.de>
233	http://home.schmorp.de/
234
235	=cut
236