cache_set

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Definition

cache_set($cid, $table = 'cache', $data, $expire = CACHE_PERMANENT, $headers = NULL)
includes/cache.inc, line 93

Description

Store data in the persistent cache.

The persistent cache is split up into four database tables. Contributed modules can add additional tables.

'cache_page': This table stores generated pages for anonymous users. This is the only table affected by the page cache setting on the administrator panel.

'cache_menu': Stores the cachable part of the users' menus.

'cache_filter': Stores filtered pieces of content. This table is periodically cleared of stale entries by cron.

'cache': Generic cache storage table.

The reasons for having several tables are as follows:

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

Parameters

$cid The cache ID of the data to store.

$table The table $table to store the data in. Valid core values are 'cache_filter', 'cache_menu', 'cache_page', or 'cache'.

$data The data to store in the cache. Complex data types must be serialized first.

$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.

$headers A string containing HTTP header information for cached pages.

Code

<?php
function cache_set($cid, $table = 'cache', $data, $expire = CACHE_PERMANENT, $headers = NULL) {
  db_lock_table($table);
  db_query("UPDATE {". $table. "} SET data = %b, created = %d, expire = %d, headers = '%s' WHERE cid = '%s'", $data, time(), $expire, $headers, $cid);
  if (!db_affected_rows()) {
    @db_query("INSERT INTO {". $table. "} (cid, data, created, expire, headers) VALUES ('%s', %b, %d, %d, '%s')", $cid, $data, time(), $expire, $headers);
  }
  db_unlock_tables();
}
?>