Differential D21585 Diff 51387 src/infrastructure/util/PhabricatorGlobalLock.php

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src/infrastructure/util/PhabricatorGlobalLock.php

Show First 20 Lines • Show All 112 Lines • ▼ Show 20 Lines	/* -( Connection Pool )---------------------------------------------------- */
public static function getConnectionPoolSize() {		public static function getConnectionPoolSize() {
return count(self::$pool);		return count(self::$pool);
}		}

public static function clearConnectionPool() {		public static function clearConnectionPool() {
self::$pool = array();		self::$pool = array();
}		}

		public static function newConnection() {
		// NOTE: Use of the "repository" database is somewhat arbitrary, mostly
		// because the first client of locks was the repository daemons.

		// We must always use the same database for all locks, because different
		// databases may be on different hosts if the database is partitioned.

		// However, we don't access any tables so we could use any valid database.
		// We could build a database-free connection instead, but that's kind of
		// messy and unusual.

		$dao = new PhabricatorRepository();

		// NOTE: Using "force_new" to make sure each lock is on its own connection.

		// See T13627. This is critically important in versions of MySQL older
		// than MySQL 5.7, because they can not hold more than one lock per
		// connection simultaneously.

		return $dao->establishConnection('w', $force_new = true);
		}

/* -( Implementation )----------------------------------------------------- */		/* -( Implementation )----------------------------------------------------- */

protected function doLock($wait) {		protected function doLock($wait) {
$conn = $this->conn;		$conn = $this->conn;

if (!$conn) {		if (!$conn) {
if ($this->externalConnection) {		if ($this->externalConnection) {
$conn = $this->externalConnection;		$conn = $this->externalConnection;
}		}
}		}

if (!$conn) {		if (!$conn) {
// Try to reuse a connection from the connection pool.		// Try to reuse a connection from the connection pool.
$conn = array_pop(self::$pool);		$conn = array_pop(self::$pool);
}		}

if (!$conn) {		if (!$conn) {
// NOTE: Using the 'repository' database somewhat arbitrarily, mostly		$conn = self::newConnection();
// because the first client of locks is the repository daemons. We must
// always use the same database for all locks, but don't access any
// tables so we could use any valid database. We could build a
// database-free connection instead, but that's kind of messy and we
// might forget about it in the future if we vertically partition the
// application.
$dao = new PhabricatorRepository();

// NOTE: Using "force_new" to make sure each lock is on its own
// connection.
$conn = $dao->establishConnection('w', $force_new = true);
}		}

// See T13627. We must never hold more than one lock per connection, so		// See T13627. We must never hold more than one lock per connection, so
// make sure this connection has no existing locks. (Normally, we should		// make sure this connection has no existing locks. (Normally, we should
// only be able to get here if callers explicitly provide the same external		// only be able to get here if callers explicitly provide the same external
// connection to multiple locks.)		// connection to multiple locks.)

if ($conn->isHoldingAnyLock()) {		if ($conn->isHoldingAnyLock()) {
Show All 26 Lines	if (!$ok) {
// 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.

		// See T13627. If this is an external connection, don't put it into
		// the shared connection pool.

		if (!$this->externalConnection) {
self::$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));
}		}

$conn->rememberLock($lock_name);		$conn->rememberLock($lock_name);

$this->conn = $conn;		$this->conn = $conn;
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