1 files changed, 82 insertions, 0 deletions
diff --git a/www/wiki/includes/libs/lockmanager/PostgreSqlLockManager.php b/www/wiki/includes/libs/lockmanager/PostgreSqlLockManager.php
new file mode 100644
index 00000000..65c69938
--- /dev/null
+++ b/www/wiki/includes/libs/lockmanager/PostgreSqlLockManager.php
@@ -0,0 +1,82 @@
+<?php
+
+use Wikimedia\Rdbms\DBError;
+
+/**
+ * PostgreSQL version of DBLockManager that supports shared locks.
+ * All locks are non-blocking, which avoids deadlocks.
+ *
+ * @ingroup LockManager
+ */
+class PostgreSqlLockManager extends DBLockManager {
+	/** @var array Mapping of lock types to the type actually used */
+	protected $lockTypeMap = [
+		self::LOCK_SH => self::LOCK_SH,
+		self::LOCK_UW => self::LOCK_SH,
+		self::LOCK_EX => self::LOCK_EX
+	];
+
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
+		$status = StatusValue::newGood();
+		if ( !count( $paths ) ) {
+			return $status; // nothing to lock
+		}
+
+		$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
+		$bigints = array_unique( array_map(
+			function ( $key ) {
+				return Wikimedia\base_convert( substr( $key, 0, 15 ), 16, 10 );
+			},
+			array_map( [ $this, 'sha1Base16Absolute' ], $paths )
+		) );
+
+		// Try to acquire all the locks...
+		$fields = [];
+		foreach ( $bigints as $bigint ) {
+			$fields[] = ( $type == self::LOCK_SH )
+				? "pg_try_advisory_lock_shared({$db->addQuotes( $bigint )}) AS K$bigint"
+				: "pg_try_advisory_lock({$db->addQuotes( $bigint )}) AS K$bigint";
+		}
+		$res = $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
+		$row = $res->fetchRow();
+
+		if ( in_array( 'f', $row ) ) {
+			// Release any acquired locks if some could not be acquired...
+			$fields = [];
+			foreach ( $row as $kbigint => $ok ) {
+				if ( $ok === 't' ) { // locked
+					$bigint = substr( $kbigint, 1 ); // strip off the "K"
+					$fields[] = ( $type == self::LOCK_SH )
+						? "pg_advisory_unlock_shared({$db->addQuotes( $bigint )})"
+						: "pg_advisory_unlock({$db->addQuotes( $bigint )})";
+				}
+			}
+			if ( count( $fields ) ) {
+				$db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
+			}
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-acquirelock', $path );
+			}
+		}
+
+		return $status;
+	}
+
+	/**
+	 * @see QuorumLockManager::releaseAllLocks()
+	 * @return StatusValue
+	 */
+	protected function releaseAllLocks() {
+		$status = StatusValue::newGood();
+
+		foreach ( $this->conns as $lockDb => $db ) {
+			try {
+				$db->query( "SELECT pg_advisory_unlock_all()", __METHOD__ );
+			} catch ( DBError $e ) {
+				$status->fatal( 'lockmanager-fail-db-release', $lockDb );
+			}
+		}
+
+		return $status;
+	}
+}