snapshot: add some basic blurs and error logging to snapshots

common/src/promise-utils.ts

@@ -0,0 +1,36 @@
+export interface RefreshPromise<T> {
+    promise: Promise<T>;
+    cacheDuration: number;
+}
+
+export function singletonPromise<T>(rp: RefreshPromise<T>, method: () => Promise<T>) {
+    if (rp?.promise)
+        return rp;
+
+    const promise = method();
+    if (!rp) {
+        rp = {
+            promise,
+            cacheDuration: 0,
+        }
+    }
+    else {
+        rp.promise = promise;
+    }
+    promise.finally(() => setTimeout(() => rp.promise = undefined, rp.cacheDuration));
+    return rp;
+}
+
+export class TimeoutError extends Error {
+    constructor() {
+        super('Operation Timed Out');
+    }
+}
+
+export function timeoutPromise<T>(timeout: number, promise: Promise<T>): Promise<T> {
+    return new Promise<T>((resolve, reject) => {
+        setTimeout(() => reject(new TimeoutError()), timeout);
+        promise.then(resolve);
+        promise.catch(reject);
+    })
+}