Issue #3264313: do not return cached items after a cache flush

      // items that expired before present time.

      $cache_timestamp_expired = variable_get('memcache_expire_wait_gc', FALSE) ? ($cache->expire + $this->cache_lifetime <= $this->cache_temporary_flush) : ($cache->expire <= REQUEST_TIME);

      // Items created before the last full wildcard flush against this bin are

      // always invalid.

      if ($cache->created <= $this->cache_flush) {

        $cache = FALSE;

      }

      // Test for expired items.

      if (($cache->expire == CACHE_TEMPORARY && $cache_garbage_collected) || ($cache->expire > 0 && $cache_timestamp_expired)) {

      elseif (($cache->expire == CACHE_TEMPORARY && $cache_garbage_collected) || ($cache->expire > 0 && $cache_timestamp_expired)) {

        // If the memcache_stampede_protection variable is set, allow one

        // process to rebuild the cache entry while serving expired content to

        // the rest. Note that core happily returns expired cache items as valid

        // and relies on cron to expire them, but this is mostly reliant on its

        // use of CACHE_TEMPORARY which does not map well to memcache.

        // @see http://drupal.org/node/534092

        if (variable_get('memcache_stampede_protection', FALSE)) {

        if (variable_get('memcache_stampede_protection', FALSE) && $this->stampedeProtected($cid)) {

          // The process that acquires the lock will get a cache miss, all

          // others will get a cache hit.

          if ($this->lockInit() && $this->stampedeProtected($cid) && lock_acquire("memcache_$cid:$this->bin", variable_get('memcache_stampede_semaphore', 15))) {

          if ($this->lockInit() && lock_acquire("memcache_$cid:$this->bin", variable_get('memcache_stampede_semaphore', 15))) {

            $cache = FALSE;

          }

        }

          $cache = FALSE;

        }

      }

      // Items created before the last full wildcard flush against this bin are

      // invalid.

      elseif ($cache->created <= $this->cache_flush) {

        $cache = FALSE;

      }

      // Items created before the last content flush on this bin i.e.

      // cache_clear_all() are invalid.

      elseif ($cache->expire != CACHE_PERMANENT && $cache->created + $this->cache_lifetime <= $this->cache_content_flush) {