make a new package for helpers

packages/helpers/async-queue.ts

@@ -0,0 +1,25 @@
+export type AsyncCallback = () => unknown
+
+export class AsyncQueue {
+  private callbacks: AsyncCallback[] = []
+  private promise: Promise<void> | undefined
+
+  async add(callback: AsyncCallback) {
+    this.callbacks.push(callback)
+    if (this.promise) return this.promise
+
+    this.promise = this.runQueue()
+    try {
+      await this.promise
+    } finally {
+      this.promise = undefined
+    }
+  }
+
+  private async runQueue() {
+    let callback: AsyncCallback | undefined
+    while ((callback = this.callbacks.shift())) {
+      await callback()
+    }
+  }
+}