NAME

       CHI::Driver::File - File-based cache using one file per entry in a multi-level directory
       structure

VERSION

       version 0.60

SYNOPSIS

           use CHI;

           my $cache = CHI->new(
               driver         => 'File',
               root_dir       => '/path/to/cache/root',
               depth          => 3,
               max_key_length => 64
           );

DESCRIPTION

       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 NFS.

       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 given entry.

CONSTRUCTOR OPTIONS

       When using this driver, the following options can be passed to CHI->new() in addition to
       the CHI.

       root_dir
           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.

       depth
           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).

       dir_create_mode
           Permissions mode to use when creating directories. Defaults to 0775.

       file_create_mode
           Permissions mode to use when creating files, modified by the current umask.  Defaults
           to 0666.

       file_extension
           Extension to append to filename. Default is ".dat".

METHODS

       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.

       path_to_namespace
           Returns the full path to the directory representing this cache's namespace, whether or
           not it has any entries.

TEMPORARY FILE RENAME

       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 to either change the path of the temporary filename, or skip
       the temporary file and rename altogether by having it return undef.

SEE ALSO

       CHI

AUTHOR

       Jonathan Swartz <swartz@pobox.com>

COPYRIGHT AND LICENSE

       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.