Ubuntu Manpage: LWP::ConnCache - Connection cache manager

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 $checker argument is a subroutine that is called for each
connection. If the routine returns a TRUE value then the connection is dropped. The routine is
called with ($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 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 capacity
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::ConnCache" and perhaps override the
       deposit(), enforce_limits() and dropping() methods.

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

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