feat(nbstore): better doc sync logic (#9037)

packages/common/nbstore/src/impls/idb/lock.ts

@@ -0,0 +1,83 @@
+import EventEmitter2 from 'eventemitter2';
+
+import { type Locker } from '../../storage/lock';
+import type { IDBConnection } from './db';
+
+interface ChannelMessage {
+  type: 'unlock';
+  key: string;
+}
+
+export class IndexedDBLocker implements Locker {
+  get db() {
+    return this.dbConnection.inner.db;
+  }
+  private readonly eventEmitter = new EventEmitter2();
+
+  get channel() {
+    return this.dbConnection.inner.channel;
+  }
+
+  constructor(private readonly dbConnection: IDBConnection) {}
+
+  async lock(domain: string, resource: string) {
+    const key = `${domain}:${resource}`;
+
+    // eslint-disable-next-line no-constant-condition
+    while (true) {
+      const trx = this.db.transaction('locks', 'readwrite');
+      const record = await trx.store.get(key);
+      const lockTimestamp = record?.lock.getTime();
+
+      if (
+        lockTimestamp &&
+        lockTimestamp > Date.now() - 30000 /* lock timeout 3s */
+      ) {
+        trx.commit();
+
+        await new Promise<void>(resolve => {
+          const cleanup = () => {
+            this.channel.removeEventListener('message', channelListener);
+            this.eventEmitter.off('unlock', eventListener);
+            clearTimeout(timer);
+          };
+          const channelListener = (event: MessageEvent<ChannelMessage>) => {
+            if (event.data.type === 'unlock' && event.data.key === key) {
+              cleanup();
+              resolve();
+            }
+          };
+          const eventListener = (unlockKey: string) => {
+            if (unlockKey === key) {
+              cleanup();
+              resolve();
+            }
+          };
+          this.channel.addEventListener('message', channelListener); // add listener
+          this.eventEmitter.on('unlock', eventListener);
+
+          const timer = setTimeout(() => {
+            cleanup();
+            resolve();
+          }, 3000);
+          // timeout to avoid dead lock
+        });
+        continue;
+      } else {
+        await trx.store.put({ key, lock: new Date() });
+        trx.commit();
+        break;
+      }
+    }
+
+    return {
+      [Symbol.asyncDispose]: async () => {
+        const trx = this.db.transaction('locks', 'readwrite');
+        await trx.store.delete(key);
+        trx.commit();
+        this.channel.postMessage({ type: 'unlock', key });
+        this.eventEmitter.emit('unlock', key);
+      },
+    };
+  }
+}