Cache::Entry - phpMan

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NAME
    Cache::Entry - interface for a cache entry

SYNOPSIS
      my Cache::Entry $entry = $cache->entry( $key )
      my $data;
      if ($entry->exists()) {
          $data = $entry->get();
      }
      else {
          $data = get_some_data($key);
          $entry->set($data, '10 minutes');
      }

DESCRIPTION
    Objects derived from Cache::Entry represent an entry in a Cache. Methods
    are provided that act upon the data in the entry, and allow you to set
    things like the expiry time.

    Users should not create instances of Cache::Entry directly, but instead
    use the entry($key) method of a Cache instance.

METHODS
    my $cache = $e->cache()
        Returns a reference to the cache object this entry is from.

    my $key = $e->key()
        Returns the cache key this entry is associated with.

    my $bool = $e->exists()
        Returns a boolean value (1 or 0) to indicate whether there is any
        data present in the cache for this entry.

    $e->set( $data, [ $expiry ] )
        Stores the data into the cache. The data must be a scalar (if you
        want to store more complex data types, see freeze and thaw below).

        The expiry time may be provided as an optional 2nd argument and is
        in the same form as for 'set_expiry($time)'.

    my $data = $e->get()
        Returns the data from the cache, or undef if the entry doesn't
        exist.

    my $size = $e->size()
        Returns the size of the entry data, or undef if the entry doesn't
        exist.

    $e->remove()
        Clear the data for this entry from the cache.

    my $expiry = $e->expiry()
        Returns the expiry time of the entry, in seconds since the epoch.

    $e->set_expiry( $time )
        Set the expiry time in seconds since the epoch, or alternatively
        using a string like '10 minutes'. Valid units are s, second,
        seconds, sec, m, minute, minutes, min, h, hour, hours, w, week,
        weeks, M, month, months, y, year and years. You can also specify an
        absolute time, such as '16 Nov 94 22:28:20' or any other time that
        Date::Parse can understand. Finally, the strings 'now' and 'never'
        may also be used.

    my $fh = $e->handle( [$mode, [$expiry] ] )
        Returns an IO::Handle by which data can be read, or written, to the
        cache. This is useful if you are caching a large amount of data -
        although it should be noted that only some cache implementations
        (such as Cache::File) provide an efficient mechanism for
        implementing this.

        The optional mode argument can be any of the perl mode strings as
        used for the open function '<', '+<', '>', '+>', '>>' and '+>>'.
        Alternatively it can be the corresponding fopen(3) modes of 'r',
        'r+', 'w', 'w+', 'a' and 'a+'. The default mode is '+<' (or 'r+')
        indicating reading and writing.

        The second argument is used to set the expiry time for the entry if
        it doesn't exist already and the handle is opened for writing. It is
        also used to reset the expiry time if the entry is truncated by
        opening in the '>' or '+>' modes. If the expiry is not provided in
        these situations then the default expiry time for the cache is
        applied.

        Cache implementations will typically provide locking around cache
        entries, so that writers will have have an exclusive lock and
        readers a shared one. Thus the method get() (or obtaining another
        handle) should be avoided whilst a write handle is held. Using set()
        or remove(), however, should be supported. These clear the current
        entry and whilst they do not invalidate open handles, those handle
        will from then on refer to old data and any changes to the data will
        be discarded.

STORING VALIDITY OBJECTS
    There are two additional set & get methods that can be used to store a
    validity object that is associated with the data in question. Typically
    this is useful in conjunction with a validate_callback, and may be used
    to store a timestamp or similar to validate against. The validity data
    stored may be any complex data that can be serialized via Storable.

    $e->validity()
    $e->set_validity( $data )

STORING COMPLEX OBJECTS
    The set and get methods only allow for working with simple scalar types,
    but if you want to store more complex types they need to be serialized
    first. To assist with this, the freeze and thaw methods are provided.
    They are simple wrappers to get & set that use Storable to do the
    serialization and de-serialization of the data.

    Note, however, that you must be careful to ONLY use 'thaw' on data that
    was stored via 'freeze'. Otherwise the stored data wont actually be in
    Storable format and it will complain loudly.

    $e->freeze( $data, [ $expiry ] )
        Identical to 'set', except that data may be any complex data type
        that can be serialized via Storable.

    $e->thaw()
        Identical to 'get', except that it will return a complex data type
        that was set via 'freeze'.

SEE ALSO
    Cache, Cache::File

AUTHOR
     Chris Leishman <chris AT leishman.org>
     Based on work by DeWitt Clinton <dewitt AT unto.net>

COPYRIGHT
     Copyright (C) 2003-2006 Chris Leishman.  All Rights Reserved.

    This module is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
    KIND, either expressed or implied. This program is free software; you
    can redistribute or modify it under the same terms as Perl itself.

    $Id: Entry.pm,v 1.8 2006/01/31 15:23:58 caleishm Exp $


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