protected function MemcacheBackend::valid in Zircon Profile 8

Same name and namespace in other branches

1. 8.0 modules/memcache/src/MemcacheBackend.php \Drupal\memcache\MemcacheBackend::valid()

1 call to MemcacheBackend::valid()

MemcacheBackend::getMultiple in modules/memcache/src/MemcacheBackend.php

Returns data from the persistent cache when given an array of cache IDs.

File

modules/memcache/src/MemcacheBackend.php, line 116

Contains \Drupal\memcache\MemcacheBackend.

Class

MemcacheBackend

Defines a Memcache cache backend.

Namespace

Drupal\memcache

Code

protected function valid($cid, $cache) {
  $lock_key = "memcache_{$cid}:{$this->bin}";
  $cache->valid = FALSE;
  if ($cache) {

    // Items that have expired are invalid.
    if (isset($cache->expire) && $cache->expire != CacheBackendInterface::CACHE_PERMANENT && $cache->expire <= REQUEST_TIME) {

      // If the memcache_stampede_protection variable is set, allow one
      // process to rebuild the cache entry while serving expired content to
      // the rest.
      if ($this->settings
        ->get('memcache_stampede_protection', FALSE)) {

        // The process that acquires the lock will get a cache miss, all
        // others will get a cache hit.
        if (!$this->lock
          ->acquire($lock_key, $this->settings
          ->get('memcache_stampede_semaphore', 15))) {
          $cache->valid = TRUE;
        }
      }
    }
    else {
      $cache->valid = TRUE;
    }
  }
  else {
    if ($this->settings
      ->get('memcache_stampede_protection', FALSE) && !$this->lock
      ->acquire($lock_key, $this->settings
      ->get('memcache_stampede_semaphore', 15))) {

      // Prevent any single request from waiting more than three times due to
      // stampede protection. By default this is a maximum total wait of 15
      // seconds. This accounts for two possibilities - a cache and lock miss
      // more than once for the same item. Or a cache and lock miss for
      // different items during the same request.
      // @todo: it would be better to base this on time waited rather than
      // number of waits, but the lock API does not currently provide this
      // information. Currently the limit will kick in for three waits of 25ms
      // or three waits of 5000ms.
      $this->lockCount++;
      if ($this->lockCount <= $this->settings
        ->get('memcache_stampede_wait_limit', 3)) {

        // The memcache_stampede_semaphore variable was used in previous
        // releases of memcache, but the max_wait variable was not, so by
        // default divide the semaphore value by 3 (5 seconds).
        $this->lock
          ->wait($lock_key, $this->settings
          ->get('memcache_stampede_wait_time', 5));
        $cache = $this
          ->get($cid);
      }
    }
  }

  // Check if invalidateTags() has been called with any of the items's tags.
  if (!$this->checksumProvider
    ->isValid($cache->checksum, $cache->tags)) {
    $cache->valid = FALSE;
  }
  return (bool) $cache->valid;
}