Introduction
Tech Note
Current implementation uses a caching library called Stash, via Stash-bundle. If this changes, then the configuration format will most likely change as well. Stash supports the following cache handlers: FileSystem, Memcache, APC, Sqlite, XCache and BlackHole.
Cache service
The cache system is exposed as a "cache" service, and can be reused by any other service as described on the Persistence cache page.
Configuration
During Setup wizard and manually using ezpublish:configure console command a default configuration is generated currently using FileSystem, using %kernel.cache_dir%/stash to store cache files. It falls back to BlackHole, a non caching cache handler.
The configuration is placed in ezpublish/config/ezpublish.yml, and looks like:
Default ezpublish.yml
The default settings used during setup wizard as found in ezpublish/config/ezpublish_setup.yml:
ezpublish_setup.yml
This setting works across all installs and just caches objects within the same request thanks to the inMemory: true setting.
If you want to change to another handler, see below for what kind of settings you have available.
Note for multiple sites installation
As cache configuration is global to the application, it's currently not possible to have different cache configuration by siteaccess. As such, when having multiple websites using different content repositories, you must only use the BlackHole handler with inMemory caching:
This will result to the same persistence cache strategy as in eZ Publish 4.x.
Note for "inMemory" cache with long running scripts
Use of inMemory caching with BlackHole or any other cache handler should not be used for long running scripts as it will over time return stale data (inMemory cache is not shared across requests/processes, so invalidation does not happen)!
Stash handlers configuration
General settings
To check which cache settings are available for your installation, run the following command in your terminal :
FileSystem
This cache handler is using local filesystem, by default the Symfony cache folder, as this is per server, it does not support multi server (cluster) setups!
We strongly discourage you from storing cache files on NFS, as it defeats the purpose of the cache: speed
Available settings
path | The path where the cache is placed, default is %kernel.cache_dir%/stash, effectively ezpublish/cache/<env>/stash |
dirSplit | Number of times the cache key should be split up to avoid having to many files in each folder, default is 2. |
filePermissions | The permissions of the cache file, default is 0660. |
dirPermissions | The permission of the cache file directories (see dirSplit), default is 0770. |
memKeyLimit | Limit on how many key to path entries are kept in memory during execution at a time to avoid having to recalculate the path on key lookups, default 200. |
keyHashFunction | Algorithm used for creating paths, default |
Issues with Microsoft Windows
If you are using a Windows OS, you may encounter an issue regarding long paths for cache directory name. The paths are long because Stash uses md5 to generate unique key that are sanitized really quickly.
Solution is to change the hash algorithm used by Stash.
Specifying key hash function
This configuration is only recommended for Windows users.
Note : you can also define the path where you want the cache files to be generated.
APC
This cache handler is using shard memory using APC's user cache feature, as this is per server, it does not support multi server (cluster) setups, unless you use PHP-FPM on a dedicated server (this way, user cache can be shared among all the workers in one pool).
Limitation
As APC user cache is not shared between processes, it is not possible to clear the user cache from CLI, even if you set apc.enable_cli to On.
Hence publishing content from a command line script won't let you properly clear SPI cache.
Please also note that the default value for apc.shm_size is 128MB. However, 256MB is recommended for APC to work properly. For more details please refer to the APC configuration manual.
Available settings
ttl | The time to live of the cache in seconds, default set to 500 (8.3 minutes) |
namespace | A namespace to prefix cache keys with to avoid key conflicts with other eZ Publish sites on same eZ Publish installation, default is null. |
Memcache
This cache handler is using Memcached, a distributed caching solution, this is the only supported cache solution for multi server (cluster) setups!
Note
servers | Array of Memcached servers, with host/IP, port and weight
|
prefix_key | A namespace to prefix cache keys with to avoid key conflicts with other eZ Publish sites on same eZ Publish installation (default is an empty string). Must be the same on all server with the same installation. See Memcached option. |
compression | default true. See Memcached option. |
libketama_compatible | default false. See Memcached option |
buffer_writes | default false. See Memcached option |
binary_protocol | default false. See Memcached option |
no_block | default false. See Memcached option |
tcp_nodelay | default false. See Memcached option |
connection_timeout | default 1000. See Memcached option |
retry_timeout | default 0. See Memcached option |
send_timeout | default 0. See Memcached option |
recv_timeout | default 0. See Memcached option |
poll_timeout | default 1000. See Memcached option |
cache_lookups | default false. See Memcached option |
server_failure_limit | default 0. See Memcached option |
For in-depth information on the settings, see: http://php.net/Memcached
When using Memcache handler, it's strongly recommended to also use inMemory cache (see example below).
This will help reducing network traffic between your webserver and your Memcached server.