mod_cache_socache
Shared object cache (socache) based storage module for the HTTP caching filter.
Extension
mod_cache_socache.c
cache_socache_module

mod_cache_socache implements a shared object cache (socache) based storage manager for mod_cache.

The headers and bodies of cached responses are combined, and stored underneath a single key in the shared object cache. A number of implementations of shared object caches are available to choose from.

Multiple content negotiated responses can be stored concurrently, however the caching of partial content is not yet supported by this module.

# Turn on caching CacheSocache shmcb CacheSocacheMaxSize 102400 <Location /foo> CacheEnable socache </Location>

# Fall back to the disk cache CacheSocache shmcb CacheSocacheMaxSize 102400 <Location /foo> CacheEnable socache CacheEnable disk </Location>

# Note:

mod_cache_socache requires the services of mod_cache, which must be loaded before mod_cache_socache.

mod_cache
mod_cache_disk
Caching Guide
CacheSocache
The shared object cache implementation to use
CacheSocache type[:args]
server config
virtual host
Available in Apache 2.4.5 and later

The CacheSocache directive defines the name of the shared object cache implementation to use, followed by optional arguments for that implementation. A number of implementations of shared object caches are available to choose from.

CacheSocache shmcb
CacheSocacheMaxTime
The maximum time (in seconds) for a document to be placed in the cache
CacheSocacheMaxTime seconds
CacheSocacheMaxTime 86400
server config
virtual host
directory
.htaccess
Available in Apache 2.4.5 and later

The CacheSocacheMaxTime directive sets the maximum freshness lifetime, in seconds, for a document to be stored in the cache. This value overrides the freshness lifetime defined for the document by the HTTP protocol.

CacheSocacheMaxTime 86400
CacheSocacheMinTime
The minimum time (in seconds) for a document to be placed in the cache
CacheSocacheMinTime seconds
CacheSocacheMinTime 600
server config
virtual host
directory
.htaccess
Available in Apache 2.4.5 and later

The CacheSocacheMinTime directive sets the amount of seconds beyond the freshness lifetime of the response that the response should be cached for in the shared object cache. If a response is only stored for its freshness lifetime, there will be no opportunity to revalidate the response to make it fresh again.

CacheSocacheMinTime 600
CacheSocacheMaxSize
The maximum size (in bytes) of an entry to be placed in the cache
CacheSocacheMaxSize bytes
CacheSocacheMaxSize 102400
server config
virtual host
directory
.htaccess
Available in Apache 2.4.5 and later

The CacheSocacheMaxSize directive sets the maximum size, in bytes, for the combined headers and body of a document to be considered for storage in the cache. The larger the headers that are stored alongside the body, the smaller the body may be.

The mod_cache_socache module will only attempt to cache responses that have an explicit content length, or that are small enough to be written in one pass. This is done to allow the mod_cache_disk module to have an opportunity to cache responses larger than those cacheable within mod_cache_socache.

CacheSocacheMaxSize 102400
CacheSocacheReadSize
The minimum size (in bytes) of the document to read and be cached before sending the data downstream
CacheSocacheReadSize bytes
CacheSocacheReadSize 0
server config
virtual host
directory
.htaccess
Available in Apache 2.4.5 and later

The CacheSocacheReadSize directive sets the minimum amount of data, in bytes, to be read from the backend before the data is sent to the client. The default of zero causes all data read of any size to be passed downstream to the client immediately as it arrives. Setting this to a higher value causes the disk cache to buffer at least this amount before sending the result to the client. This can improve performance when caching content from a slow reverse proxy.

This directive only takes effect when the data is being saved to the cache, as opposed to data being served from the cache.

CacheReadSize 102400
CacheSocacheReadTime
The minimum time (in milliseconds) that should elapse while reading before data is sent downstream
CacheSocacheReadTime milliseconds
CacheSocacheReadTime 0
server config
virtual host
directory
.htaccess
Available in Apache 2.4.5 and later

The CacheSocacheReadTime directive sets the minimum amount of elapsed time that should pass before making an attempt to send data downstream to the client. During the time period, data will be buffered before sending the result to the client. This can improve performance when caching content from a reverse proxy.

The default of zero disables this option.

This directive only takes effect when the data is being saved to the cache, as opposed to data being served from the cache. It is recommended that this option be used alongside the CacheSocacheReadSize directive to ensure that the server does not buffer excessively should data arrive faster than expected.

CacheSocacheReadTime 1000