ChainedFastBackend::markAsOutdated

protected ChainedFastBackend::markAsOutdated()

protected function markAsOutdated() {
  // Clocks on a single server can drift. Multiple servers may have slightly
  // differing opinions about the current time. Given that, do not assume
  // 'now' on this server is always later than our stored timestamp.
  // Also add 1 millisecond, to ensure that caches written earlier in the same
  // millisecond are invalidated. It is possible that caches will be later in
  // the same millisecond and are then incorrectly invalidated, but that only
  // costs one additional roundtrip to the persistent cache.
  $now = round(microtime(TRUE) + .001, 3);
  if ($now > $this->getLastWriteTimestamp()) {
    $this->lastWriteTimestamp = $now;
    $this->consistentBackend->set(self::LAST_WRITE_TIMESTAMP_PREFIX . $this->bin, $this->lastWriteTimestamp);
  }
}