[TYPO3-core] FYI72: enhancements to memcached caching backend

[Karsten Dambekalns]

Hi Dmitry.

On 03.12.2008, at 21:30, Dmitry Dulepov wrote:
> Problems:
> 1. memcached backend does not support connections through Unix  
> sockets ("unix:///var/run/memcached.sock")
> Solution:
> 1. enable support for Unix sockets (this is official way to do it,  
> not a hack!)

Agreed, makes sense.

> Problems:
> 2. if memcached server is unavailable, this fact will be detected  
> too late (when using get/set) and nasty error message will be shown
> Solution:
> 2. use "connect" instead of "addServer"
Here we loose failover within the connection pool. Here's what the  
docs say about addServer():

  --- snip ---

When using this method (as opposed to Memcache::connect() and  
Memcache::pconnect()) the network connection is not established until  
actually needed. Thus there is no overhead in adding a large number of  
servers to the pool, even though they might not all be used.

Failover may occur at any stage in any of the methods, as long as  
other servers are available the request the user won't notice. Any  
kind of socket or Memcached server level errors (except out-of-memory)  
may trigger the failover. Normal client errors such as adding an  
existing key will not trigger a failover.

  --- snip ---

addServer() accepts unix sockets the same way as connect(), so those  
can be combined. It makes sense to look at what happens when a server  
is not available, given the fact that an error is counter-productive  
to failover. ;)

So the patch could look like this:

> Index: t3lib/cache/backend/class.t3lib_cache_backend_memcached.php
> ===================================================================
> --- t3lib/cache/backend/class.t3lib_cache_backend_memcached.php	 
> (revision 4519)
> +++ t3lib/cache/backend/class.t3lib_cache_backend_memcached.php	 
> (working copy)
> @@ -111,8 +111,13 @@
> 		}
>
> 		foreach ($this->servers as $serverConf) {
> -			$conf = explode(':',$serverConf, 2);
> -			$this->memcache->addServer($conf[0], $conf[1]);
> +			if (substr($serverConf, 0, 7) == 'unix://') {
> +				$this->memcache->addServer($serverConf, 0);
> +			}
> +			else {
> +				$conf = explode(':',$serverConf, 2);
> +				$this->memcache->addServer($conf[0], $conf[1]);
> +			}
> 		}
> 	}

Regards,
Karsten
-- 
Karsten Dambekalns
Gimme Five!
http://typo3.org/gimmefive


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