Manpages - LWP_ConnCache.3pm
Table of Contents
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) {
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.