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src/infrastructure/util/PhabricatorGlobalLock.php
| Show First 20 Lines • Show All 143 Lines • ▼ Show 20 Lines | if (!$conn) { | ||||
| // application. | // application. | ||||
| $dao = new PhabricatorRepository(); | $dao = new PhabricatorRepository(); | ||||
| // NOTE: Using "force_new" to make sure each lock is on its own | // NOTE: Using "force_new" to make sure each lock is on its own | ||||
| // connection. | // connection. | ||||
| $conn = $dao->establishConnection('w', $force_new = true); | $conn = $dao->establishConnection('w', $force_new = true); | ||||
| } | } | ||||
| // See T13627. We must never hold more than one lock per connection, so | |||||
| // make sure this connection has no existing locks. (Normally, we should | |||||
| // only be able to get here if callers explicitly provide the same external | |||||
| // connection to multiple locks.) | |||||
| if ($conn->isHoldingAnyLock()) { | |||||
| throw new Exception( | |||||
| pht( | |||||
| 'Unable to establish lock on connection: this connection is '. | |||||
| 'already holding a lock. Acquiring a second lock on the same '. | |||||
| 'connection would release the first lock in MySQL versions '. | |||||
| 'older than 5.7.')); | |||||
| } | |||||
| // NOTE: Since MySQL will disconnect us if we're idle for too long, we set | // NOTE: Since MySQL will disconnect us if we're idle for too long, we set | ||||
| // the wait_timeout to an enormous value, to allow us to hold the | // the wait_timeout to an enormous value, to allow us to hold the | ||||
| // connection open indefinitely (or, at least, for 24 days). | // connection open indefinitely (or, at least, for 24 days). | ||||
| $max_allowed_timeout = 2147483; | $max_allowed_timeout = 2147483; | ||||
| queryfx($conn, 'SET wait_timeout = %d', $max_allowed_timeout); | queryfx($conn, 'SET wait_timeout = %d', $max_allowed_timeout); | ||||
| $lock_name = $this->getName(); | $lock_name = $this->getName(); | ||||
| $result = queryfx_one( | $result = queryfx_one( | ||||
| $conn, | $conn, | ||||
| 'SELECT GET_LOCK(%s, %f)', | 'SELECT GET_LOCK(%s, %f)', | ||||
| $lock_name, | $lock_name, | ||||
| $wait); | $wait); | ||||
| $ok = head($result); | $ok = head($result); | ||||
| if (!$ok) { | if (!$ok) { | ||||
| // See PHI1794. We failed to acquire the lock, but the connection itself | // See PHI1794. We failed to acquire the lock, but the connection itself | ||||
| // is still good. We're done with it, so add it to the pool, just as we | // is still good. We're done with it, so add it to the pool, just as we | ||||
| // would if we were releasing the lock. | // would if we were releasing the lock. | ||||
| // If we don't do this, we may establish a huge number of connections | // If we don't do this, we may establish a huge number of connections | ||||
| // very rapidly if many workers try to acquire a lock at once. For | // very rapidly if many workers try to acquire a lock at once. For | ||||
| // example, this can happen if there are a large number of webhook tasks | // example, this can happen if there are a large number of webhook tasks | ||||
| // in the queue. | // in the queue. | ||||
| self::$pool[] = $conn; | self::$pool[] = $conn; | ||||
| throw id(new PhutilLockException($lock_name)) | throw id(new PhutilLockException($lock_name)) | ||||
| ->setHint($this->newHint($lock_name, $wait)); | ->setHint($this->newHint($lock_name, $wait)); | ||||
| ▲ Show 20 Lines • Show All 226 Lines • Show Last 20 Lines | |||||