cache_set

Stores data in the persistent cache.

The persistent cache is split up into several cache bins. In the default cache implementation, each cache bin corresponds to a database table by the same name. Other implementations might want to store several bins in data structures that get flushed together. While it is not a problem for most cache bins if the entries in them are flushed before their expire time, some might break functionality or are extremely expensive to recalculate. These will be marked with a (*). The other bins expired automatically by core. Contributed modules can add additional bins and get them expired automatically by implementing hook_flush_caches().

• cache: Generic cache storage bin (used for variables, theme registry,

locale date, list of simpletest tests etc).

• cache_block: Stores the content of various blocks.

• cache field: Stores the field data belonging to a given object.

• cache_filter: Stores filtered pieces of content.

• cache_form(*): Stores multistep forms. Flushing this bin means that some

forms displayed to users lose their state and the data already submitted to them.

• cache_menu: Stores the structure of visible navigation menus per page.

• cache_page: Stores generated pages for anonymous users. It is flushed

very often, whenever a page changes, at least for every ode and comment submission. This is the only bin affected by the page cache setting on the administrator panel.

• cache path: Stores the system paths that have an alias.

• cache update(*): Stores available releases. The update server (for

example, drupal.org) needs to produce the relevant XML for every project installed on the current site. As this is different for (almost) every site, it's very expensive to recalculate for the update server.

The reasons for having several bins are as follows:

• smaller bins mean smaller database tables and allow for faster selects and inserts
• we try to put fast changing cache items and rather static ones into different bins. The effect is that only the fast changing bins will need a lot of writes to disk. The more static bins will also be better cacheable with MySQL's query cache.

Parameters

$cid: The cache ID of the data to store.

$data: The data to store in the cache. Complex data types will be automatically serialized before insertion. Strings will be stored as plain text and not serialized.

$bin: The cache bin to store the data in. Valid core values are 'cache_block', 'cache_bootstrap', 'cache_field', 'cache_filter', 'cache_form', 'cache_menu', 'cache_page', 'cache_update' or 'cache' for the default cache.

$expire: One of the following values:

• CACHE_PERMANENT: Indicates that the item should never be removed unless explicitly told to using cache_clear_all() with a cache ID.
• CACHE_TEMPORARY: Indicates that the item should be removed at the next general cache wipe.
• A Unix timestamp: Indicates that the item should be kept at least until the given time, after which it behaves like CACHE_TEMPORARY.

See also

cache_get()

44 calls to cache_set()

File

includes/cache.inc, line 146

Functions and interfaces for cache handling.

Code

function cache_set($cid, $data, $bin = 'cache', $expire = CACHE_PERMANENT) {
  return _cache_get_object($bin)->set($cid, $data, $expire);
}