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IPC::Cmd::Cached 0.01
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NAME
IPC::Cmd::Cached - Run expensive commands and cache their output
SYNOPSIS
use IPC::Cmd::Cached;
my $runner = IPC::Cmd::Cached->new();
# takes a fair mount to run, but result gets cached
my($success, $error_code, $full_buf, $stdout_buf, $stderr_buf) =
$runner->run(command => "find /etc -type f -print");
# Returns the same result much faster, because it's cached
my($success, $error_code, $full_buf, $stdout_buf, $stderr_buf) =
$runner->run_cached("find /etc -type f -print");
# To make sure the cached entries don't expire, run this
# twice a day via a cronjob:
$runner->run_all();
DESCRIPTION
"IPC::Cmd::Cached" uses "IPC::Cmd" to run arbitrary shell commands, but
caches their results and finds them later.
It uses a "Cache::FileCache" object to store the output of commands it
has successfully executed persistently on disk. Results are store under
a key equal to the command line given to run the commands.
If a command's output doesn't change much over time and cached results
are acceptable, "IPC::Cmd::Cached" saves time by reusing canned results
instead of recalculating the same results over and over again.
"IPC::Cmd::Cached" works like the "Memoize" module, but instead of
caching the output of functions, it caches the output of external
scripts.
CAVEATS
A command's results are cached based on its full command line. This
might not be desirable if the same command produces varying output over
time:
$ eg/run-cached date
Mon Dec 17 00:01:00 PST 2007
$ eg/run-cached -c date
Mon Dec 17 00:01:00 PST 2007
Advanced use cases
The constructor accepts arguments to change the runner's internal
behavior:
cache
By default, this is set to a Cache::FileCache object in the default
namespace with 24 hours of expiration time:
my $runner = IPC::Cmd::Cached->new(
cache => Cache::FileCache->new({
auto_purge_on_get => 1,
default_expires_in => 24*3600,
namespace => "IPC-Cmd-Cached",
}),
);
If you need different characteristics, define your own cache object
and hand it over to "new" as shown above. Take a look at the
Cache::Cache documentation for details.
EXAMPLES
The distribution comes with two utility scripts, "run-cached" and
"run-cached-all".
"run-cached" runs a command specified on its command line. With the -c
option, it will fetch the cached entry instead.
"run-cached-all" runs all scripts in the cache to refresh their content.
Check the documentation that comes with these scripts for more details.
LEGALESE
Copyright 2007 by Mike Schilli, all rights reserved. This program is
free software, you can redistribute it and/or modify it under the same
terms as Perl itself.
AUTHOR
2007, Mike Schilli <cpan@perlmeister.com>