Add generics to server add-on connection

Reviewed By: mweststrate

Differential Revision: D34307356

fbshipit-source-id: 27e61355a85995368ebb197c42d58f4145473567

desktop/flipper-common/src/utils/controlledPromise.tsx

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+type Res<T> = {
+  promise: Promise<T>;
+  resolve: (...res: T extends void ? [] : [T]) => void;
+  reject: (reason: unknown) => void;
+} & (
+  | {
+      state: 'pending';
+      promiseVal: undefined;
+    }
+  | {state: 'resolved'; promiseVal: T}
+  | {state: 'rejected'; promiseVal: unknown}
+);
+
+export const createControlledPromise = <T,>(): Res<T> => {
+  let resolve!: Res<T>['resolve'];
+  let reject!: Res<T>['reject'];
+  let state: 'pending' | 'resolved' | 'rejected' = 'pending';
+  let promiseVal: T | unknown | undefined;
+  const promise = new Promise<T>((resolveP, rejectP) => {
+    resolve = ((val) => {
+      state = 'resolved';
+      promiseVal = val;
+      resolveP(val as T | PromiseLike<T>);
+    }) as typeof resolve;
+    reject = (err) => {
+      state = 'rejected';
+      promiseVal = err;
+      rejectP(err);
+    };
+  });
+  return {
+    promise,
+    resolve,
+    reject,
+    state,
+    promiseVal,
+  } as Res<T>;
+};