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# Copyright (C) 2008 Arne Georg Gleditsch <lxr@linux.no>.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# The full GNU General Public License is included in this distribution
# in the file called COPYING.
package LXRng::Cached;
use strict;
use LXRng;
require Exporter;
use vars qw($memcached $has_memcached $nspace @ISA @EXPORT);
@ISA = qw(Exporter);
@EXPORT = qw(cached);
BEGIN {
eval { require Cache::Memcached;
require Storable;
require Digest::SHA1;
};
if ($@ eq '') {
$has_memcached = 1;
$nspace = substr(Digest::SHA1::sha1_hex($LXRng::ROOT), 0, 8);
}
}
sub handle {
return undef unless $has_memcached;
return $memcached if $memcached;
$memcached = Cache::Memcached->new({
'servers' => ['127.0.0.1:11211'],
'namespace' => 'lxrng:$nspace'});
unless ($memcached->set(':caching' => 1)) {
$memcached = undef;
$has_memcached = undef;
}
return $memcached;
}
# Caches result from block enclosed by cache { ... }. File/linenumber
# of the "cache" keyword is used as the caching key. If additional
# arguments are given after the sub to cache, they are used to further
# specify the caching key. Otherwise, the arguments supplied to the
# function containing the call to cached are used.
sub cached(&;@);
*cached = \&DB::LXRng_Cached_cached;
package DB;
sub LXRng_Cached_cached(&;@) {
my ($func, @args) = @_;
if (LXRng::Cached::handle) {
my ($pkg, $file, $line) = caller(0);
my $params;
unless (@args > 0) {
my @caller = caller(1);
@args = map { UNIVERSAL::can($_, 'cache_key') ? $_->cache_key : $_
} @DB::args;
}
$params = Storable::freeze(\@args);
my $key = Digest::SHA1::sha1_hex(join("\0", $file, $line, $params));
my $val = LXRng::Cached::handle->get($key);
unless ($val) {
$val = [$func->()];
LXRng::Cached::handle->set($key, $val, 3600);
# warn "cache miss for $key (".join(":", $file, $line, @args).")\n";
}
else {
# warn "cache hit for $key\n";
}
return @$val;
}
else {
return $func->();
}
}
1;
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