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 = 4.748;
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;
   $buf
}

sub nfreeze($) {
   open my $fh, ">:cede($GRANULARITY)", \my $buf
      or die "cannot open pst via PerlIO::cede: $!";
   Storable::nstore_fd $_[0], $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:	1.29
Committed:	Wed Sep 24 21:31:29 2008 UTC (15 years, 9 months ago) by root
Branch:	MAIN
Changes since 1.28:	+10 -12 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=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	root	1.22	so that it cede's more often. Some applications (such as the Deliantra
13	root	1.1	game server) sometimes need to load large Storable objects without
14			blocking the server for a long time.
15
16	root	1.6	This is being implemented by using a perlio layer that feeds only small
17	root	1.29	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	root	1.6
20	root	1.29	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	root	1.2
24	root	1.1	=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	root	1.29	This function will cede regularly.
35	root	1.1
36			=item $pst = freeze $ref
37
38			Freeze the given scalar into a Storable object. It uses the same format as
39	root	1.6	C<Storable::store_fd>.
40	root	1.1
41	root	1.29	This functino will cede regularly.
42	root	1.1
43	root	1.6	=item $pst = nfreeze $ref
44
45	root	1.7	Same as C<freeze> but is compatible to C<Storable::nstore_fd> (note the
46	root	1.6	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	root	1.7	C<Storable::freeze> for this as Storable uses incompatible formats for
54	root	1.29	memory and file images, and this module uses file images.
55	root	1.6
56			=item $pst = blocking_nfreeze $ref
57
58			Same as C<blocking_freeze> but uses C<nfreeze> internally.
59
60	root	1.22	=item $guard = guard
61	root	1.8
62			Acquire the Storable lock, for when you want to call Storable yourself.
63
64	root	1.29	Note that this module already wraps all Storable functions, so there is
65	root	1.22	rarely the need to do this yourself.
66
67	root	1.1	=back
68
69			=cut
70
71			package Coro::Storable;
72
73	root	1.22	use strict qw(subs vars);
74	root	1.13	no warnings;
75	root	1.1
76			use Coro ();
77	root	1.2	use Coro::Semaphore ();
78	root	1.1
79	root	1.13	BEGIN {
80			# suppress warnings
81			local $^W = 0;
82			require Storable;
83			}
84
85	root	1.1	use Storable;
86			use base "Exporter";
87
88	root	1.26	our $VERSION = 4.748;
89	root	1.9	our @EXPORT = qw(thaw freeze nfreeze blocking_thaw blocking_freeze blocking_nfreeze);
90	root	1.1
91	root	1.29	our $GRANULARITY = 0.01;
92	root	1.28
93	root	1.2	my $lock = new Coro::Semaphore;
94
95	root	1.8	sub guard {
96			$lock->guard
97			}
98
99	root	1.22	# wrap xs functions
100	root	1.26	for (qw(net_pstore pstore net_mstore mstore pretrieve mretrieve dclone)) {
101	root	1.22	my $orig = \&{"Storable::$_"};
102			*{"Storable::$_"} = sub {
103			my $guard = $lock->guard;
104			&$orig
105			};
106			die if $@;
107			}
108
109	root	1.6	sub thaw($) {
110	root	1.28	open my $fh, "<:cede($GRANULARITY)", \$_[0]
111			or die "cannot open pst via PerlIO::cede: $!";
112	root	1.6	Storable::fd_retrieve $fh
113			}
114
115	root	1.1	sub freeze($) {
116	root	1.28	open my $fh, ">:cede($GRANULARITY)", \my $buf
117			or die "cannot open pst via PerlIO::cede: $!";
118	root	1.6	Storable::store_fd $_[0], $fh;
119	root	1.1	$buf
120			}
121
122	root	1.6	sub nfreeze($) {
123	root	1.28	open my $fh, ">:cede($GRANULARITY)", \my $buf
124			or die "cannot open pst via PerlIO::cede: $!";
125	root	1.6	Storable::nstore_fd $_[0], $fh;
126			$buf
127			}
128
129	root	1.10	sub blocking_thaw($) {
130	root	1.9	open my $fh, "<", \$_[0]
131			or die "cannot open pst: $!";
132			Storable::fd_retrieve $fh
133			}
134
135	root	1.10	sub blocking_freeze($) {
136	root	1.6	open my $fh, ">", \my $buf
137			or die "cannot open pst: $!";
138			Storable::store_fd $_[0], $fh;
139			close $fh;
140
141			$buf
142			}
143
144	root	1.10	sub blocking_nfreeze($) {
145	root	1.6	open my $fh, ">", \my $buf
146			or die "cannot open pst: $!";
147			Storable::nstore_fd $_[0], $fh;
148			close $fh;
149
150			$buf
151	root	1.1	}
152
153			1;
154
155			=head1 AUTHOR
156
157			Marc Lehmann <schmorp@schmorp.de>
158			http://home.schmorp.de/
159
160			=cut
161
162