Load limiting safeguards

dashboard/src/components/config.js

@@ -1,2 +1,27 @@
 export const API = "http://127.0.0.1:8000";
 export const POLL = 15_000;
+export const POLL_HEAVY = 60_000;
+export const POLL_HIDDEN = 120_000;
+export const FETCH_TIMEOUT = 12_000;
+
+export function pollDelay({ok = true, base = POLL, failures = 0} = {}) {
+  const hidden = typeof document !== "undefined" && document.visibilityState === "hidden";
+  const failureDelay = ok ? base : Math.min(base * 2 ** Math.min(failures, 4), 300_000);
+  return hidden ? Math.max(failureDelay, POLL_HIDDEN) : failureDelay;
+}
+
+export function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+
+export async function apiFetch(path, options = {}) {
+  const url = path.startsWith("http") ? path : `${API}${path}`;
+  const timeout = options.timeout ?? FETCH_TIMEOUT;
+  const ctrl = new AbortController();
+  const timer = setTimeout(() => ctrl.abort(), timeout);
+  try {
+    return await fetch(url, {...options, signal: ctrl.signal});
+  } finally {
+    clearTimeout(timer);
+  }
+}