LWP::ConnCache

LWP::ConnCache(3)     User Contributed Perl Documentation    LWP::ConnCache(3)



NAME
       LWP::ConnCache - Connection cache manager

NOTE
       This module is experimental.  Details of its interface is likely to
       change in the future.

SYNOPSIS
        use LWP::ConnCache;
        my $cache = LWP::ConnCache->new;
        $cache->deposit($type, $key, $sock);
        $sock = $cache->withdraw($type, $key);

DESCRIPTION
       The "LWP::ConnCache" class is the standard connection cache manager for
       LWP::UserAgent.

       The following basic methods are provided:

       $cache = LWP::ConnCache->new( %options )
           This method constructs a new "LWP::ConnCache" object.  The only
           option currently accepted is 'total_capacity'.  If specified it
           initialize the total_capacity option.  It defaults to the value 1.

       $cache->total_capacity( [$num_connections] )
           Get/sets the number of connection that will be cached.  Connections
           will start to be dropped when this limit is reached.  If set to 0,
           then all connections are immediately dropped.  If set to "undef",
           then there is no limit.

       $cache->capacity($type, [$num_connections] )
           Get/set a limit for the number of connections of the specified type
           that can be cached.  The $type will typically be a short string
           like "http" or "ftp".

       $cache->drop( [$checker, [$reason]] )
           Drop connections by some criteria.  The $checker argument is a sub-
           routine that is called for each connection.  If the routine returns
           a TRUE value then the connection is dropped.  The routine is called
           with ($conn, $type, $key, $deposit_time) as arguments.

           Shortcuts: If the $checker argument is absent (or "undef") all
           cached connections are dropped.  If the $checker is a number then
           all connections untouched that the given number of seconds or more
           are dropped.  If $checker is a string then all connections of the
           given type are dropped.

           The $reason argument is passed on to the dropped() method.

       $cache->prune
           Calling this method will drop all connections that are dead.  This
           is tested by calling the ping() method on the connections.  If the
           ping() method exists and returns a FALSE value, then the connection
           is dropped.

       $cache->get_types
           This returns all the 'type' fields used for the currently cached
           connections.

       $cache->get_connections( [$type] )
           This returns all connection objects of the specified type.  If no
           type is specified then all connections are returned.  In scalar
           context the number of cached connections of the specified type is
           returned.

       The following methods are called by low-level protocol modules to try
       to save away connections and to get them back.

       $cache->deposit($type, $key, $conn)
           This method adds a new connection to the cache.  As a result other
           already cached connections might be dropped.  Multiple connections
           with the same $type/$key might added.

       $conn = $cache->withdraw($type, $key)
           This method tries to fetch back a connection that was previously
           deposited.  If no cached connection with the specified $type/$key
           is found, then "undef" is returned.  There is not guarantee that a
           deposited connection can be withdrawn, as the cache manger is free
           to drop connections at any time.

       The following methods are called internally.  Subclasses might want to
       override them.

       $conn->enforce_limits([$type])
           This method is called with after a new connection is added
           (deposited) in the cache or capacity limits are adjusted.  The
           default implementation drops connections until the specified capac-
           ity limits are not exceeded.

       $conn->dropping($conn_record, $reason)
           This method is called when a connection is dropped.  The record
           belonging to the dropped connection is passed as the first argument
           and a string describing the reason for the drop is passed as the
           second argument.  The default implementation makes some noise if
           the $LWP::ConnCache::DEBUG variable is set and nothing more.

SUBCLASSING
       For specialized cache policy it makes sense to subclass "LWP::Con-
       nCache" and perhaps override the deposit(), enforce_limits() and drop-
       ping() methods.

       The object itself is a hash.  Keys prefixed with "cc_" are reserved for
       the base class.

SEE ALSO
       LWP::UserAgent

COPYRIGHT
       Copyright 2001 Gisle Aas.

       This library is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.



perl v5.8.6                       2004-04-09                 LWP::ConnCache(3)