function dmemcache_get in Memcache API and Integration 5

Same name and namespace in other branches

1. 5.2 dmemcache.inc \dmemcache_get()
2. 6 dmemcache.inc \dmemcache_get()
3. 7 dmemcache.inc \dmemcache_get()

Retrieve a value from the cache.

Parameters

$key The key with which the item was stored.:

$bin The bin in which the item was stored.:

Return value

The item which was originally saved or FALSE

5 calls to dmemcache_get()

cache_get in ./memcache.db.inc

Return data from the persistent cache.

cache_get in ./memcache.inc

Return data from the persistent cache.

sess_read in ./memcache-session.inc

sess_regenerate in ./memcache-session.inc

sess_user_load in ./memcache-session.inc

File

./dmemcache.inc, line 56

Code

function dmemcache_get($key, $bin = 'cache') {
  global $_memcache_statistics;
  $_memcache_statistics['get'][] = $key;
  $_memcache_statistics['bins'][] = $bin;
  if ($mc = dmemcache_object($bin)) {
    $full_key = dmemcache_key($key, $bin);
    $result = $mc
      ->get($full_key);
    if ($result) {

      // We check $result->expire to see if the object has expired.  If so, we
      // try and grab a lock.  If we get the lock, we return FALSE instead of
      // the cached object which should cause it to be rebuilt.  If we do not
      // get the lock, we return the cached object.  The goal here is to avoid
      // cache stampedes.
      // By default the cache stampede semaphore is held for 15 seconds.  This
      // can be adjusted by setting the memcache_stampede_semaphore variable.
      // TODO: Can we log when a sempahore expires versus being intentionally
      // freed to track when this is happening?
      if (isset($result->expire) && $result->expire <= $_SERVER['REQUEST_TIME'] && $mc
        ->add($full_key . '_semaphore', '', FALSE, variable_get('memcache_stampede_semaphore', 15))) {
        $result = FALSE;
      }
      else {
        $_memcache_statistics['hit'][] = $key;
      }
    }
    return $result;
  }
}