CHI::Driver::File - File-based cache using one file per entry in a multi-level
my $cache = CHI->new(
driver => 'File',
root_dir => '/path/to/cache/root',
depth => 3,
max_key_length => 64
This cache driver stores data on the filesystem, so that it can be shared
between processes on a single machine, or even on multiple machines if using
Each item is stored in its own file. By default, during a set, a temporary file
is created and then atomically renamed to the proper file. While not the most
efficient, it eliminates the need for locking (with multiple overlapping sets,
the last one "wins") and makes this cache usable in environments
like NFS where locking might normally be undesirable.
By default, the base filename is the key itself, with unsafe characters escaped
similar to URL escaping. If the escaped key is larger than
"max_key_length" (default 248 characters), it will be digested. You
may want to lower "max_key_length" if you are storing a lot of items
as long filenames can be more expensive to work with.
The files are evenly distributed within a multi-level directory structure with a
customizable "depth", to minimize the time needed to search for a
When using this driver, the following options can be passed to CHI->
in addition to the CHI.
- The location in the filesystem that will hold the root of
the cache. Defaults to a directory called 'chi-driver-file' under the OS
default temp directory (e.g. '/tmp' on UNIX). This directory will be
created as needed on the first cache set.
- The number of subdirectories deep to place cache files.
Defaults to 2. This should be large enough that no leaf directory has more
than a few hundred files. Each non-leaf directory contains up to 16
subdirectories (0-9, A-F).
- Permissions mode to use when creating directories. Defaults
- Permissions mode to use when creating files, modified by
the current umask. Defaults to 0666.
- Extension to append to filename. Default is
- path_to_key ( $key )
- Returns the full path to the cache file representing $key,
whether or not that entry exists. Returns the empty list if a valid path
cannot be computed, for example if the key is too long.
- Returns the full path to the directory representing this
cache's namespace, whether or not it has any entries.
By default, during a set, a temporary file is created and then atomically
renamed to the proper file. This eliminates the need for locking. You can
subclass and override method generate_temporary_filename
change the path of the temporary filename, or skip the temporary file and
rename altogether by having it return undef.
Jonathan Swartz <firstname.lastname@example.org>
This software is copyright (c) 2012 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.