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.

METHODS

       The following basic methods are provided:

   new
           my $cache = LWP::ConnCache->new( %options )

       This method constructs a new LWP::ConnCache object.  The only option currently accepted is
       "total_capacity".  If specified it initializes the "total_capacity" in LWP::ConnCache
       option. It defaults to 1.

   total_capacity
           my $cap = $cache->total_capacity;
           $cache->total_capacity(0); # drop all immediately
           $cache->total_capacity(undef); # no limit
           $cache->total_capacity($number);

       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.

   capacity
           my $http_capacity = $cache->capacity('http');
           $cache->capacity('http', 2 );

       Get/set a limit for the number of connections of the specified type that can be cached.
       The first parameter is a short string like "http" or "ftp".

   drop
           $cache->drop(); # Drop ALL connections
           # which is just a synonym for:
           $cache->drop(sub{1}); # Drop ALL connections
           # drop all connections older than 22 seconds and add a reason for it!
           $cache->drop(22, "Older than 22 secs dropped");
           # which is just a synonym for:
           $cache->drop(sub {
               my ($conn, $type, $key, $deposit_time) = @_;
               if ($deposit_time < 22) {
                   # true values drop the connection
                   return 1;
               }
               # false values don't drop the connection
               return 0;
           }, "Older than 22 secs dropped" );

       Drop connections by some criteria.  The $checker argument is a subroutine that is called
       for each connection.  If the routine returns a TRUE value then the connection is dropped.
       The routine is called with "($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" is passed on to the "dropped" in LWP::ConnCache method.

   prune
           $cache->prune();

       Calling this method will drop all connections that are dead.  This is tested by calling
       the "ping" in LWP::ConnCache method on the connections. If the "ping" in LWP::ConnCache
       method exists and returns a false value, then the connection is dropped.

   get_types
           my @types = $cache->get_types();

       This returns all the "type" fields used for the currently cached connections.

   get_connections
           my @conns = $cache->get_connections(); # all connections
           my @conns = $cache->get_connections('http'); # connections for http

       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.

PROTOCOL METHODS

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

   deposit
           $cache->deposit($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 be added.

   withdraw
           my $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.

INTERNAL METHODS

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

   enforce_limits
           $conn->enforce_limits([$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 capacity limits are not exceeded.

   dropping
           $conn->dropping($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::ConnCache" and perhaps
       override the "deposit" in LWP::ConnCache, "enforce_limits" in LWP::ConnCache, and
       "dropping" in LWP::ConnCache 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.