public function add($key, $value, $exptime = 0)
{
$this->debugLog("add({$key})");
return $this->checkResult($key, parent::add($key, $value, $exptime));
}
/**
* @param MemcachedBagOStuff $memc
* @param array $keys List of keys to acquire
* @return bool
*/
protected function acquireMutexes(MemcachedBagOStuff $memc, array $keys)
{
$lockedKeys = [];
// Acquire the keys in lexicographical order, to avoid deadlock problems.
// If P1 is waiting to acquire a key P2 has, P2 can't also be waiting for a key P1 has.
sort($keys);
// Try to quickly loop to acquire the keys, but back off after a few rounds.
// This reduces memcached spam, especially in the rare case where a server acquires
// some lock keys and dies without releasing them. Lock keys expire after a few minutes.
$rounds = 0;
$start = microtime(true);
do {
if (++$rounds % 4 == 0) {
usleep(1000 * 50);
// 50 ms
}
foreach (array_diff($keys, $lockedKeys) as $key) {
if ($memc->add("{$key}:mutex", 1, 180)) {
// lock record
$lockedKeys[] = $key;
} else {
continue;
// acquire in order
}
}
} while (count($lockedKeys) < count($keys) && microtime(true) - $start <= 3);
if (count($lockedKeys) != count($keys)) {
$this->releaseMutexes($memc, $lockedKeys);
// failed; release what was locked
return false;
}
return true;
}
/**
* @param MemcachedBagOStuff $memc
* @param array $keys List of keys to acquire
* @return bool
*/
protected function acquireMutexes(MemcachedBagOStuff $memc, array $keys)
{
$lockedKeys = [];
// Acquire the keys in lexicographical order, to avoid deadlock problems.
// If P1 is waiting to acquire a key P2 has, P2 can't also be waiting for a key P1 has.
sort($keys);
// Try to quickly loop to acquire the keys, but back off after a few rounds.
// This reduces memcached spam, especially in the rare case where a server acquires
// some lock keys and dies without releasing them. Lock keys expire after a few minutes.
$loop = new WaitConditionLoop(function () use($memc, $keys, &$lockedKeys) {
foreach (array_diff($keys, $lockedKeys) as $key) {
if ($memc->add("{$key}:mutex", 1, 180)) {
// lock record
$lockedKeys[] = $key;
}
}
return array_diff($keys, $lockedKeys) ? WaitConditionLoop::CONDITION_CONTINUE : true;
}, 3.0);
$loop->invoke();
if (count($lockedKeys) != count($keys)) {
$this->releaseMutexes($memc, $lockedKeys);
// failed; release what was locked
return false;
}
return true;
}
