fix: resolve batch with pending values as well

this solves an issue where cachified would never resolve when
two batches were executed in parallel with partially overlapping keys

fix #119

Author: Xiphe

src/cachified.spec.ts

@@ -1413,6 +1413,41 @@ describe('cachified', () => {
     expect(cache.get('test-2')).toBe(undefined);
   });
 
+  it('de-duplicates batched cache calls', async () => {
+    const cache = new Map<string, CacheEntry>();
+
+    function getValues(indexes: number[], callId: number) {
+      const batch = createBatch((freshIndexes: number[]) =>
+        freshIndexes.map((i) => `value-${i}-call-${callId}`),
+      );
+
+      return Promise.all(
+        indexes.map((index) =>
+          cachified({
+            cache,
+            key: `test-${index}`,
+            ttl: Infinity,
+            getFreshValue: batch.add(index),
+          }),
+        ),
+      );
+    }
+
+    const batch1 = getValues([1, 2, 3], 1);
+    const batch2 = getValues([1, 2, 5], 2);
+
+    expect(await batch1).toEqual([
+      'value-1-call-1',
+      'value-2-call-1',
+      'value-3-call-1',
+    ]);
+    expect(await batch2).toEqual([
+      'value-1-call-1',
+      'value-2-call-1',
+      'value-5-call-2',
+    ]);
+  });
+
   it('does not invoke onValue when value comes from cache', async () => {
     const cache = new Map<string, CacheEntry>();
     const onValue = jest.fn();

src/cachified.ts

@@ -4,6 +4,7 @@ import {
   Cache,
   CacheEntry,
   createContext,
+  HANDLE,
 } from './common';
 import { CACHE_EMPTY, getCachedValue } from './getCachedValue';
 import { getFreshValue } from './getFreshValue';
@@ -53,6 +54,8 @@ export async function cachified<Value>(
   if (pendingValues.has(key)) {
     const { value: pendingRefreshValue, metadata } = pendingValues.get(key)!;
     if (!shouldRefresh(metadata)) {
+      /* Notify batch that we handled this call using pending value */
+      context.getFreshValue[HANDLE]?.();
       report({ name: 'getFreshValueHookPending' });
       const value = await pendingRefreshValue;
       report({ name: 'done', value });