Fix sync batching in keepFresh

.changeset/calm-carrots-compete.md

@@ -0,0 +1,5 @@
+---
+'@farfetched/core': patch
+---
+
+Fix sync batching in `keepFresh`

packages/core/project.json

@@ -71,7 +71,7 @@
     "size": {
       "executor": "./tools/executors/size-limit:size-limit",
       "options": {
-        "limit": "18.5 kB",
+        "limit": "18.9 kB",
         "outputPath": "dist/packages/core"
       },
       "dependsOn": [

packages/core/src/libs/patronus/index.ts

@@ -18,3 +18,4 @@ export {
 export { type FetchingStatus } from './status';
 export { time } from './time';
 export { and } from './and';
+export { syncBatch } from './sync_batch';

packages/core/src/libs/patronus/sync_batch.ts

@@ -0,0 +1,84 @@
+// Copied and adopted https://github.com/effector/patronum/blob/main/src/debounce/index.ts
+
+import {
+  createEvent,
+  createStore,
+  type Event,
+  type EventAsReturnType,
+  sample,
+  attach,
+} from 'effector';
+
+export function syncBatch<T>(clock: Event<T>): EventAsReturnType<T> {
+  const saveTimeoutId = createEvent<NodeJS.Timeout>();
+
+  const $timeoutId = createStore<NodeJS.Timeout | null>(null, {
+    serialize: 'ignore',
+  }).on(saveTimeoutId, (_, id) => id);
+
+  const saveReject = createEvent<() => void>();
+
+  const $rejecter = createStore<(() => void) | null>(null, {
+    serialize: 'ignore',
+  }).on(saveReject, (_, rj) => rj);
+
+  const tick = createEvent<T>();
+
+  const timerFx = attach({
+    source: {
+      timeoutId: $timeoutId,
+      rejectPromise: $rejecter,
+    },
+    effect: ({ timeoutId, rejectPromise }) => {
+      if (timeoutId) clearTimeout(timeoutId);
+      if (rejectPromise) rejectPromise();
+      return new Promise((resolve, reject) => {
+        saveReject(reject);
+        saveTimeoutId(setTimeout(resolve, 0));
+      });
+    },
+  });
+  $rejecter.reset(timerFx.done);
+  $timeoutId.reset(timerFx.done);
+
+  // It's ok - nothing will ever start unless source is triggered
+  const $payload = createStore<T[]>([], { serialize: 'ignore' }).on(
+    clock,
+    (_, payload) => [payload]
+  );
+
+  const $canTick = createStore(true, { serialize: 'ignore' });
+
+  const triggerTick = createEvent();
+
+  $canTick
+    .on(triggerTick, () => false)
+    .on(
+      [
+        tick,
+        // debounce timeout can be restarted in later ticks
+        timerFx,
+      ],
+      () => true
+    );
+
+  sample({
+    clock: clock,
+    filter: $canTick,
+    target: triggerTick,
+  });
+
+  sample({
+    clock: triggerTick,
+    target: timerFx,
+  });
+
+  sample({
+    source: $payload,
+    clock: timerFx.done,
+    fn: ([payload]) => payload,
+    target: tick,
+  });
+
+  return tick;
+}

packages/core/src/trigger_api/keep_fresh.ts

@@ -5,15 +5,14 @@ import {
   sample,
   is,
   createStore,
-  merge,
 } from 'effector';
 
 import { type Query } from '../query/type';
 import { divide, get, isEqual } from '../libs/lohyphen';
 import {
   not,
   and,
-  delay,
+  syncBatch,
   normalizeSourced,
   extractSource,
 } from '../libs/patronus';
@@ -139,8 +138,7 @@ export function keepFresh<Params>(
 
   // @ts-expect-error TS cannot get that if query.$idle is false, then $latestParams is Params
   sample({
-    // Use sync batching
-    clock: delay({ clock: forceFresh, timeout: 0 }),
+    clock: syncBatch(forceFresh),
     source: query.__.$latestParams,
     filter: not(query.$idle),
     target: query.refresh,