function ChainedFastBackend::markAsOutdated

Marks the fast cache bin as outdated because of a write.

File

core/lib/Drupal/Core/Cache/ChainedFastBackend.php, line 314

Class

ChainedFastBackend

Defines a backend with a fast and a consistent backend chain.

Namespace

Code

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. Add one
  // second to the current time each time we write it to the persistent cache
  // and make sure it is always at least 1ms ahead of the current time. This
  // somewhat protects against clock drift, while also reducing the number of
  // persistent cache writes to one every second if this method is called
  // multiple times during a request. Reads and writes from the fast cache
  // are skipped when this timestamp is in the future, which also helps to
  // avoid write contention on the fast cache.
  $compare = round(microtime(TRUE) + 0.001, 3);
  if ($compare > $this->getLastWriteTimestamp()) {
    $now = round(microtime(TRUE) + 1, 3);
    $this->lastWriteTimestamp = $now;
    $this->consistentBackend
      ->set(self::LAST_WRITE_TIMESTAMP_PREFIX . $this->bin, $this->lastWriteTimestamp);
  }
}