Fix locking (#586)

* Fix migration locking

* Release lock after running migrations

src/runner.ts

@@ -51,12 +51,20 @@ const loadMigrations = async (db: DBConnection, options: RunnerOption, logger: L
 }
 
 const lock = async (db: DBConnection): Promise<void> => {
-  const [lockObtained] = await db.select(`select pg_try_advisory_lock(${PG_MIGRATE_LOCK_ID}) as "lockObtained"`)
-  if (!lockObtained) {
+  const [result] = await db.select(`select pg_try_advisory_lock(${PG_MIGRATE_LOCK_ID}) as "lockObtained"`)
+  if (!result.lockObtained) {
     throw new Error('Another migration is already running')
   }
 }
 
+const unlock = async (db: DBConnection): Promise<void> => {
+  const [result] = await db.select(`select pg_advisory_unlock(${PG_MIGRATE_LOCK_ID}) as "lockReleased"`)
+
+  if (!result.lockReleased) {
+    throw new Error('Failed to release migration lock')
+  }
+}
+
 const ensureMigrationsTable = async (db: DBConnection, options: RunnerOption): Promise<void> => {
   try {
     const schema = getMigrationTableSchema(options)
@@ -220,6 +228,9 @@ export default async (options: RunnerOption): Promise<RunMigration[]> => {
       timestamp: m.timestamp,
     }))
   } finally {
+    if (!options.noLock) {
+      await unlock(db).catch((error) => logger.warn(error.message))
+    }
     db.close()
   }
 }