Create a Cache Provider class in Symfony - php

Question

We have memcache on our Symfony 3.4 app:
cache:
app: cache.adapter.memcached
default_memcached_provider: "%app.memcached.dsn%"
However, we've been asked to use several cache servers, so just passing one DSN is no good.
Looking here (https://symfony.com/blog/new-in-symfony-3-3-memcached-cache-adapter), I see you can create it in code like this:
$client = MemcachedAdapter::createConnection(array(
// format => memcached://[user:pass#][ip|host|socket[:port]][?weight=int]
// 'weight' ranges from 0 to 100 and it's used to prioritize servers
'memcached://my.server.com:11211'
'memcached://rmf:abcdef#localhost'
'memcached://127.0.0.1?weight=50'
'memcached://username:the-password#/var/run/memcached.sock'
'memcached:///var/run/memcached.sock?weight=20'
));
However, that isn't autowired.
I believe we need to either make a provider class, or somehow get it to make calls to addServer($dsn), once instantiated. I also saw the following on random posts:
memcache:
class: Memcached
calls:
- [ addServer, [ %app.memcached.dsn.1% ]]
- [ addServer, [ %app.memcached.dsn.2% ]]
However it isn't really helping or I have missed something out.
Can anyone help? How do I create this provider class?

Answer 1

You can copy above code snippet as a service configuration to your services.yaml, which probably roughly looks like this:
# app/config/services.yaml
services:
app.memcached_client:
class: Memcached
factory: 'Symfony\Component\Cache\Adapter\MemcachedAdapter::createConnection'
arguments: [['memcached://my.server.com:11211', 'memcached://rmf:abcdef#localhost']]
app.memcached_adapter:
class: Symfony\Component\Cache\Adapter\MemcachedAdapter
arguments:
- '#app.memcached_client'
Then in your configuration you should be able to reference the adapter using the client created by the factory, e.g. something like:
# app/config/config.yaml
framework:
cache:
app: app.memcached_adapter
You might also be able to overwrite the default alias cache.adapter.memcached instead of having your own adapter.
Your approach using Memcached::addServer might work as well, but just like with MemcachedAdapter::createConnection this will return the Client, which needs to be passed to the cache adapter. That's why there is a second service app.memcached_adapter, which is used in the cache configuration.
Please be aware that I have not tested this, so this is rather a rough outline than a fully working solution,

Answer 2

For one of my projects running Symfony 3.4 the configuration was simpler:
Create a service that will be used as a client:
app.memcached_client:
class: Memcached
factory: ['AppBundle\Services\Memcached', 'createConnection']
arguments: ['memcached://%memcache_ip%:%memcache_port%']
The AppBundle\Services\Memcached can have all the custom logic I need like so:
class Memcached
{
public static function createConnection($dns)
{
$options = [
'persistent_id' => 'some id'
];
// Some more custom logic. Maybe adding some custom options
// For example for AWS Elasticache
if (defined('Memcached::OPT_CLIENT_MODE') && defined('Memcached::DYNAMIC_CLIENT_MODE')) {
$options['CLIENT_MODE'] = \Memcached::DYNAMIC_CLIENT_MODE;
}
return \Symfony\Component\Cache\Adapter\MemcachedAdapter::createConnection($dns, $options);
}
}
And then I used that service in my config.yml:
framework:
cache:
default_memcached_provider: app.memcached_client