AP Lock (#5410)

src/misc/app-lock.ts

@@ -0,0 +1,22 @@
+import redis from '../db/redis';
+import { promisify } from 'util';
+
+/**
+ * Retry delay (ms) for lock acquisition
+ */
+const retryDelay = 100;
+
+const lock: (key: string, timeout?: number) => Promise<() => void>
+	= redis
+	? promisify(require('redis-lock')(redis, retryDelay))
+	: async () => () => { };
+
+/**
+ * Get AP Object lock
+ * @param uri AP object ID
+ * @param timeout Lock timeout (ms), The timeout releases previous lock.
+ * @returns Unlock function
+ */
+export function getApLock(uri: string, timeout = 30 * 1000) {
+	return lock(`ap-object:${uri}`, timeout);
+}