reorg again, absolute (module) imports

app/util/PromiseQueue.ts

@@ -0,0 +1,31 @@
+type QueuedPromise = () => Promise<any>
+
+class PromiseQueue {
+  maxSimultaneously: number
+
+  private active = 0
+  private queue: QueuedPromise[] = []
+
+  constructor(maxSimultaneously = 1) {
+    this.maxSimultaneously = maxSimultaneously
+  }
+
+  async enqueue<T>(func: () => Promise<T>) {
+    if (++this.active > this.maxSimultaneously) {
+      await new Promise(resolve => this.queue.push(resolve as QueuedPromise))
+    }
+
+    try {
+      return await func()
+    } catch (err) {
+      throw err
+    } finally {
+      this.active--
+      if (this.queue.length) {
+        this.queue.shift()?.()
+      }
+    }
+  }
+}
+
+export default PromiseQueue