1LWP::ConnCache(3) User Contributed Perl Documentation LWP::ConnCache(3)
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6 LWP::ConnCache - Connection cache manager
7
9 This module is experimental. Details of its interface is likely to
10 change in the future.
11
13 use LWP::ConnCache;
14 my $cache = LWP::ConnCache->new;
15 $cache->deposit($type, $key, $sock);
16 $sock = $cache->withdraw($type, $key);
17
19 The "LWP::ConnCache" class is the standard connection cache manager for
20 LWP::UserAgent.
21
23 The following basic methods are provided:
24 new
26 my $cache = LWP::ConnCache->new( %options )
27 This method constructs a new LWP::ConnCache object. The only option
29 currently accepted is "total_capacity". If specified it initialize the
30 "total_capacity" in LWP::ConnCache option. It defaults to 1.
31 total_capacity
33 my $cap = $cache->total_capacity;
34 $cache->total_capacity(0); # drop all immediately
35 $cache->total_capacity(undef); # no limit
36 $cache->total_capacity($number);
37 Get/sets the number of connection that will be cached. Connections
39 will start to be dropped when this limit is reached. If set to 0, then
40 all connections are immediately dropped. If set to "undef", then there
41 is no limit.
42 capacity
44 my $http_capacity = $cache->capacity('http');
45 $cache->capacity('http', 2 );
46 Get/set a limit for the number of connections of the specified type
48 that can be cached. The first parameter is a short string like "http"
49 or "ftp".
50 drop
52 $cache->drop(); # Drop ALL connections
53 # which is just a synonym for:
54 $cache->drop(sub{1}); # Drop ALL connections
55 # drop all connections older than 22 seconds and add a reason for it!
56 $cache->drop(22, "Older than 22 secs dropped");
57 # which is just a synonym for:
58 $cache->drop(sub {
59 my ($conn, $type, $key, $deposit_time) = @_;
60 if ($deposit_time < 22) {
61 # true values drop the connection
62 return 1;
63 }
64 # false values don't drop the connection
65 return 0;
66 }, "Older than 22 secs dropped" );
67 Drop connections by some criteria. The $checker argument is a
69 subroutine that is called for each connection. If the routine returns
70 a TRUE value then the connection is dropped. The routine is called
71 with ($conn, $type, $key, $deposit_time) as arguments.
72 Shortcuts: If the $checker argument is absent (or "undef") all cached
74 connections are dropped. If the $checker is a number then all
75 connections untouched that the given number of seconds or more are
76 dropped. If $checker is a string then all connections of the given
77 type are dropped.
78 The "reason" is passed on to the "dropped" in LWP::ConnCache method.
80 prune
82 $cache->prune();
83 Calling this method will drop all connections that are dead. This is
85 tested by calling the "ping" in LWP::ConnCache method on the
86 connections. If the "ping" in LWP::ConnCache method exists and returns
87 a false value, then the connection is dropped.
88 get_types
90 my @types = $cache->get_types();
91 This returns all the "type" fields used for the currently cached
93 connections.
94 get_connections
96 my @conns = $cache->get_connections(); # all connections
97 my @conns = $cache->get_connections('http'); # connections for http
98 This returns all connection objects of the specified type. If no type
100 is specified then all connections are returned. In scalar context the
101 number of cached connections of the specified type is returned.
102
104 The following methods are called by low-level protocol modules to try
105 to save away connections and to get them back.
106 deposit
108 $cache->deposit($type, $key, $conn);
109 This method adds a new connection to the cache. As a result, other
111 already cached connections might be dropped. Multiple connections with
112 the same type/key might be added.
113 withdraw
115 my $conn = $cache->withdraw($type, $key);
116 This method tries to fetch back a connection that was previously
118 deposited. If no cached connection with the specified $type/$key is
119 found, then "undef" is returned. There is not guarantee that a
120 deposited connection can be withdrawn, as the cache manger is free to
121 drop connections at any time.
122
124 The following methods are called internally. Subclasses might want to
125 override them.
126 enforce_limits
128 $conn->enforce_limits([$type])
129 This method is called with after a new connection is added (deposited)
131 in the cache or capacity limits are adjusted. The default
132 implementation drops connections until the specified capacity limits
133 are not exceeded.
134 dropping
136 $conn->dropping($conn_record, $reason)
137 This method is called when a connection is dropped. The record
139 belonging to the dropped connection is passed as the first argument and
140 a string describing the reason for the drop is passed as the second
141 argument. The default implementation makes some noise if the
142 $LWP::ConnCache::DEBUG variable is set and nothing more.
143
145 For specialized cache policy it makes sense to subclass
146 "LWP::ConnCache" and perhaps override the "deposit" in LWP::ConnCache,
147 "enforce_limits" in LWP::ConnCache, and "dropping" in LWP::ConnCache
148 methods.
149 The object itself is a hash. Keys prefixed with "cc_" are reserved for
151 the base class.
152
154 LWP::UserAgent
155
157 Copyright 2001 Gisle Aas.
158 This library is free software; you can redistribute it and/or modify it
160 under the same terms as Perl itself.
161perl v5.28.0 2018-07-16 LWP::ConnCache(3)