function cache_set in Memcache API and Integration 5.2

Same name in this branch

1. 5.2 memcache.db.inc \cache_set()
2. 5.2 memcache.inc \cache_set()

Same name and namespace in other branches

1. 5 memcache.db.inc \cache_set()
2. 5 memcache.inc \cache_set()
3. 6 memcache.db.inc \cache_set()
4. 6 memcache.inc \cache_set()

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.

$db_storage: This boolean is unique to the memcache.inc implementation of cache set. It allows us to do a cache_set and not write to the database, but only to memcache.

1 call to cache_set()

cache_get in ./memcache.db.inc

Return data from the persistent cache.

File

./memcache.db.inc, line 117

Code

function cache_set($cid, $table = 'cache', $data, $expire = CACHE_PERMANENT, $headers = NULL, $db_storage = TRUE) {

  // Create new cache object.
  $cache = new stdClass();
  $cache->cid = $cid;
  $cache->data = $data;
  $cache->created = time();
  $cache->expire = $expire;
  $cache->headers = $headers;
  if ($db_storage) {
    $serialized = 0;
    if (is_object($data) || is_array($data)) {
      $data = serialize($data);
      $serialized = 1;
    }

    // Save to the database
    db_lock_table($table);
    db_query("UPDATE {$table} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, time(), $expire, $headers, $serialized, $cid);
    if (!db_affected_rows()) {
      @db_query("INSERT INTO {$table} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, time(), $expire, $headers, $serialized);
    }
    db_unlock_tables();
  }

  // Save to memcache
  if ($expire == CACHE_PERMANENT || $expire > time()) {
    dmemcache_set($cid, $cache, $expire, $table);
  }
}