Coro/Coro/Storable.pm

=head1 NAME

Coro::Storable - offer a more fine-grained Storable interface

=head1 SYNOPSIS

 use Coro::Storable;

=head1 DESCRIPTION

This module implements a few functions from the Storable module in a way
so that it cede's more often. Some applications (such as the Deliantra
game server) sometimes need to load large Storable objects without
blocking the server for a long time.

This is being implemented by using a perlio layer that feeds only small
amounts of data (4096 bytes per call) into Storable, and C<Coro::cede>'ing
regularly (at most 100 times per second by default, though).

As Storable is not reentrant, this module also wraps most functions of the
Storable module so that only one freeze or thaw is done at any one moment
(and recursive invocations are not currently supported).

=head1 FUNCTIONS

=over 4

=item $ref = thaw $pst

Retrieve an object from the given $pst, which must have been created with
C<Coro::Storable::freeze> or C<Storable::store_fd>/C<Storable::store>
(sorry, but Storable uses incompatible formats for disk/mem objects).

This function will cede regularly.

=item $pst = freeze $ref

Freeze the given scalar into a Storable object. It uses the same format as
C<Storable::store_fd>.

This functino will cede regularly.

=item $pst = nfreeze $ref

Same as C<freeze> but is compatible to C<Storable::nstore_fd> (note the
C<n>).

=item $pst = blocking_freeze $ref

Same as C<freeze> but is guaranteed to block. This is useful e.g. in
C<Coro::Util::fork_eval> when you want to serialise a data structure
for use with the C<thaw> function for this module. You cannot use
C<Storable::freeze> for this as Storable uses incompatible formats for
memory and file images, and this module uses file images.

=item $pst = blocking_nfreeze $ref

Same as C<blocking_freeze> but uses C<nfreeze> internally.

=item $guard = guard

Acquire the Storable lock, for when you want to call Storable yourself.

Note that this module already wraps all Storable functions, so there is
rarely the need to do this yourself.

=back

=cut

package Coro::Storable;

use strict qw(subs vars);
no warnings;

use Coro ();
use Coro::Semaphore ();

BEGIN {
   # suppress warnings
   local $^W = 0;
   require Storable;
}

use Storable;
use base "Exporter";

our $VERSION = 5.1;
our @EXPORT = qw(thaw freeze nfreeze blocking_thaw blocking_freeze blocking_nfreeze);

our $GRANULARITY = 0.01;

my $lock = new Coro::Semaphore;

sub guard {
   $lock->guard
}

# wrap xs functions
for (qw(net_pstore pstore net_mstore mstore pretrieve mretrieve dclone)) {
   my $orig = \&{"Storable::$_"};
   *{"Storable::$_"} = sub {
      my $guard = $lock->guard;
      &$orig
   };
   die if $@;
}

sub thaw($) {
   open my $fh, "<:cede($GRANULARITY)", \$_[0]
      or die "cannot open pst via PerlIO::cede: $!";
   Storable::fd_retrieve $fh
}

sub freeze($) {
   open my $fh, ">:cede($GRANULARITY)", \my $buf
      or die "cannot open pst via PerlIO::cede: $!";
   Storable::store_fd $_[0], $fh;
   close $fh;

   $buf
}

sub nfreeze($) {
   open my $fh, ">:cede($GRANULARITY)", \my $buf
      or die "cannot open pst via PerlIO::cede: $!";
   Storable::nstore_fd $_[0], $fh;
   close $fh;

   $buf
}

sub blocking_thaw($) {
   open my $fh, "<", \$_[0]
      or die "cannot open pst: $!";
   Storable::fd_retrieve $fh
}

sub blocking_freeze($) {
   open my $fh, ">", \my $buf
         or die "cannot open pst: $!";
   Storable::store_fd $_[0], $fh;
   close $fh;

   $buf
}

sub blocking_nfreeze($) {
   open my $fh, ">", \my $buf
         or die "cannot open pst: $!";
   Storable::nstore_fd $_[0], $fh;
   close $fh;

   $buf
}

1;

=head1 AUTHOR

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

=cut


Revision:	1.41
Committed:	Mon Nov 24 07:55:28 2008 UTC (15 years, 6 months ago) by root
Branch:	MAIN
CVS Tags:	rel-5_1, rel-5_11
Changes since 1.40:	+1 -1 lines
Log Message:	5.1
#	Content
1	=head1 NAME
2
3	Coro::Storable - offer a more fine-grained Storable interface
4
5	=head1 SYNOPSIS
6
7	use Coro::Storable;
8
9	=head1 DESCRIPTION
10
11	This module implements a few functions from the Storable module in a way
12	so that it cede's more often. Some applications (such as the Deliantra
13	game server) sometimes need to load large Storable objects without
14	blocking the server for a long time.
15
16	This is being implemented by using a perlio layer that feeds only small
17	amounts of data (4096 bytes per call) into Storable, and C<Coro::cede>'ing
18	regularly (at most 100 times per second by default, though).
19
20	As Storable is not reentrant, this module also wraps most functions of the
21	Storable module so that only one freeze or thaw is done at any one moment
22	(and recursive invocations are not currently supported).
23
24	=head1 FUNCTIONS
25
26	=over 4
27
28	=item $ref = thaw $pst
29
30	Retrieve an object from the given $pst, which must have been created with
31	C<Coro::Storable::freeze> or C<Storable::store_fd>/C<Storable::store>
32	(sorry, but Storable uses incompatible formats for disk/mem objects).
33
34	This function will cede regularly.
35
36	=item $pst = freeze $ref
37
38	Freeze the given scalar into a Storable object. It uses the same format as
39	C<Storable::store_fd>.
40
41	This functino will cede regularly.
42
43	=item $pst = nfreeze $ref
44
45	Same as C<freeze> but is compatible to C<Storable::nstore_fd> (note the
46	C<n>).
47
48	=item $pst = blocking_freeze $ref
49
50	Same as C<freeze> but is guaranteed to block. This is useful e.g. in
51	C<Coro::Util::fork_eval> when you want to serialise a data structure
52	for use with the C<thaw> function for this module. You cannot use
53	C<Storable::freeze> for this as Storable uses incompatible formats for
54	memory and file images, and this module uses file images.
55
56	=item $pst = blocking_nfreeze $ref
57
58	Same as C<blocking_freeze> but uses C<nfreeze> internally.
59
60	=item $guard = guard
61
62	Acquire the Storable lock, for when you want to call Storable yourself.
63
64	Note that this module already wraps all Storable functions, so there is
65	rarely the need to do this yourself.
66
67	=back
68
69	=cut
70
71	package Coro::Storable;
72
73	use strict qw(subs vars);
74	no warnings;
75
76	use Coro ();
77	use Coro::Semaphore ();
78
79	BEGIN {
80	# suppress warnings
81	local $^W = 0;
82	require Storable;
83	}
84
85	use Storable;
86	use base "Exporter";
87
88	our $VERSION = 5.1;
89	our @EXPORT = qw(thaw freeze nfreeze blocking_thaw blocking_freeze blocking_nfreeze);
90
91	our $GRANULARITY = 0.01;
92
93	my $lock = new Coro::Semaphore;
94
95	sub guard {
96	$lock->guard
97	}
98
99	# wrap xs functions
100	for (qw(net_pstore pstore net_mstore mstore pretrieve mretrieve dclone)) {
101	my $orig = \&{"Storable::$_"};
102	*{"Storable::$_"} = sub {
103	my $guard = $lock->guard;
104	&$orig
105	};
106	die if $@;
107	}
108
109	sub thaw($) {
110	open my $fh, "<:cede($GRANULARITY)", \$_[0]
111	or die "cannot open pst via PerlIO::cede: $!";
112	Storable::fd_retrieve $fh
113	}
114
115	sub freeze($) {
116	open my $fh, ">:cede($GRANULARITY)", \my $buf
117	or die "cannot open pst via PerlIO::cede: $!";
118	Storable::store_fd $_[0], $fh;
119	close $fh;
120
121	$buf
122	}
123
124	sub nfreeze($) {
125	open my $fh, ">:cede($GRANULARITY)", \my $buf
126	or die "cannot open pst via PerlIO::cede: $!";
127	Storable::nstore_fd $_[0], $fh;
128	close $fh;
129
130	$buf
131	}
132
133	sub blocking_thaw($) {
134	open my $fh, "<", \$_[0]
135	or die "cannot open pst: $!";
136	Storable::fd_retrieve $fh
137	}
138
139	sub blocking_freeze($) {
140	open my $fh, ">", \my $buf
141	or die "cannot open pst: $!";
142	Storable::store_fd $_[0], $fh;
143	close $fh;
144
145	$buf
146	}
147
148	sub blocking_nfreeze($) {
149	open my $fh, ">", \my $buf
150	or die "cannot open pst: $!";
151	Storable::nstore_fd $_[0], $fh;
152	close $fh;
153
154	$buf
155	}
156
157	1;
158
159	=head1 AUTHOR
160
161	Marc Lehmann <schmorp@schmorp.de>
162	http://home.schmorp.de/
163
164	=cut
165
166