function LockBackendAbstract::wait
Same name in other branches
- 8.9.x core/lib/Drupal/Core/Lock/LockBackendAbstract.php \Drupal\Core\Lock\LockBackendAbstract::wait()
- 10 core/lib/Drupal/Core/Lock/LockBackendAbstract.php \Drupal\Core\Lock\LockBackendAbstract::wait()
- 11.x core/lib/Drupal/Core/Lock/LockBackendAbstract.php \Drupal\Core\Lock\LockBackendAbstract::wait()
Overrides LockBackendInterface::wait
File
-
core/
lib/ Drupal/ Core/ Lock/ LockBackendAbstract.php, line 29
Class
- LockBackendAbstract
- Non backend related common methods implementation for lock backends.
Namespace
Drupal\Core\LockCode
public function wait($name, $delay = 30) {
// Pause the process for short periods between calling
// lock_may_be_available(). This prevents hitting the database with constant
// database queries while waiting, which could lead to performance issues.
// However, if the wait period is too long, there is the potential for a
// large number of processes to be blocked waiting for a lock, especially
// if the item being rebuilt is commonly requested. To address both of these
// concerns, begin waiting for 25ms, then add 25ms to the wait period each
// time until it reaches 500ms. After this point polling will continue every
// 500ms until $delay is reached.
// $delay is passed in seconds, but we will be using usleep(), which takes
// microseconds as a parameter. Multiply it by 1 million so that all
// further numbers are equivalent.
$delay = (int) $delay * 1000000;
// Begin sleeping at 25ms.
$sleep = 25000;
while ($delay > 0) {
// This function should only be called by a request that failed to get a
// lock, so we sleep first to give the parallel request a chance to finish
// and release the lock.
usleep($sleep);
// After each sleep, increase the value of $sleep until it reaches
// 500ms, to reduce the potential for a lock stampede.
$delay = $delay - $sleep;
$sleep = min(500000, $sleep + 25000, $delay);
if ($this->lockMayBeAvailable($name)) {
// No longer need to wait.
return FALSE;
}
}
// The caller must still wait longer to get the lock.
return TRUE;
}
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