phpMan > perldoc > LWP::ConnCache

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.