NAME
Apache::Session::Store::libmemcached - Memcached::libmemcached
VERSION
Version 0.01
SYNOPSIS
use Apache::Session::libmemcache
tie %hash, 'Apache::Session::libmemcache', $id, {
servers => ['1.2.3.4:2100', '4.3.2.1:2100'],
expiration => 300, # In seconds
log_errors => 1,
}
# to enable a simple load balancing feature
# and/or fail over
tie %hash, 'Apache::Session::libmemcache', $id, {
load_balance => [
['1.2.3.4:2100', '4.3.2.1:2100'],
['1.1.1.1:2100', '2.2.2.2:2100'],
],
failover => 1,
expiration => 300, # In seconds
log_errors => 1,
};DESCRIPTION
Apache::Session::Store::libmemcached fulfills the storage interface of Apache::Session. Session data is stored memcached using Memcached::libmemcached
CONFIGURATION
- servers
-
Array reference containing strings with the format server:port. You can include multiple servers.
- expiration
-
Optional parameter that sets the xpiration time of the session. This is takes advantage of a memcached feature that allows to set keys with expiration time. 0, undef sets no expiration time.
- log_errors
-
If this parameter is set to 1, error messages will be outputed to STDERR if a memcached operation fails.
LOAD BALANCE AND FAILOVER
- load_balance
-
You can use this paramater instead of servers. It takes multiple server pools. Each pool is represented by an array reference containing strings with the format server:port.
When this parameter is used read operations will be load balanced between the available pools.
The current balancing method is pretty straightforward. It uses the first character of the session identifier to select the pool. On average and given random session indentifiers memcache operation will be evenly distributed amongst the available pools.
- failover
-
When failover is enabled, write operations take place in all the available pools. Read operations are still load balanced. However, in the event of a read operation fail, the other available pools will be used.
METHODS
new
insert
Insert a session id into memcached. It will die if the key already exists.
update
Replace a session id into memcached.
materialize
Retrieve the content of a session id
remove
Remove a session id from mecached
_connect
Private method that takes care of connecting to the memcache servers.
_read_session
Private method to read sessions.
If load balance is enabled it will read from the right cache.
If it fails and failover is enabled, it will try to read from other pools.
_select_read_pool
Private method to select a pool to read from.
We just use 'first session id character' mod $numberOfPools to select a pool.
Note that we return the first available pool if load balance is not enabled or if there is only one pool.
_update_pools
Private method to return which pools must be updated.
If failover is not enabled only one pool is returned. Otherwise the designated pool will be returned.
_read_from_pool
Private method to read from a given pool.
If read fails it will log the error in case logging is enabled.
_write_session
Private method to set a key-value entry in all the configured pools.
_log_error_message
Private method to log error messages
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Apache::Session::libmemcachedAUTHOR
Javier Uruen Val <javi.uruen@gmail.com>
LICENSE AND COPYRIGHT
Copyright (C) 2010 Venda Ltd
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.