From e40b19c7a65d3cf418703f543410fbdc3b28df32 Mon Sep 17 00:00:00 2001
From: Joao Silva <100691367+JoaoSilvaGrafana@users.noreply.github.com>
Date: Thu, 31 Oct 2024 10:27:14 +0000
Subject: [PATCH] Combobox: Debounce async calls (#95485)

---
 .../src/components/Combobox/Combobox.test.tsx | 46 ++++++++++++++++---
 .../src/components/Combobox/Combobox.tsx      | 31 ++++++++-----
 2 files changed, 59 insertions(+), 18 deletions(-)

diff --git a/packages/grafana-ui/src/components/Combobox/Combobox.test.tsx b/packages/grafana-ui/src/components/Combobox/Combobox.test.tsx
index aadb3b65f48..462e9ca7f14 100644
--- a/packages/grafana-ui/src/components/Combobox/Combobox.test.tsx
+++ b/packages/grafana-ui/src/components/Combobox/Combobox.test.tsx
@@ -176,11 +176,11 @@ describe('Combobox', () => {
     it('should ignore late responses', async () => {
       const asyncOptions = jest.fn(async (searchTerm: string) => {
         if (searchTerm === 'a') {
-          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'first' }]), 1000));
+          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'first' }]), 1500));
         } else if (searchTerm === 'ab') {
-          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'second' }]), 200));
+          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'second' }]), 500));
         } else if (searchTerm === 'abc') {
-          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'third' }]), 500));
+          return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'third' }]), 800));
         }
         return Promise.resolve([]);
       });
@@ -189,8 +189,14 @@ describe('Combobox', () => {
 
       const input = screen.getByRole('combobox');
       await user.click(input);
-      await user.keyboard('abc');
-      jest.advanceTimersByTime(200); // Resolve the second request, should be ignored
+      await act(async () => {
+        await user.keyboard('a');
+        jest.advanceTimersByTime(200); // Skip debounce
+        await user.keyboard('b');
+        jest.advanceTimersByTime(200); // Skip debounce
+        await user.keyboard('c');
+        jest.advanceTimersByTime(500); // Resolve the second request, should be ignored
+      });
 
       let firstItem = screen.queryByRole('option', { name: 'first' });
       let secondItem = screen.queryByRole('option', { name: 'second' });
@@ -200,7 +206,7 @@ describe('Combobox', () => {
       expect(secondItem).not.toBeInTheDocument();
       expect(thirdItem).not.toBeInTheDocument();
 
-      jest.advanceTimersByTime(500); // Resolve the third request, should be shown
+      jest.advanceTimersByTime(800); // Resolve the third request, should be shown
 
       firstItem = screen.queryByRole('option', { name: 'first' });
       secondItem = screen.queryByRole('option', { name: 'second' });
@@ -210,7 +216,7 @@ describe('Combobox', () => {
       expect(secondItem).not.toBeInTheDocument();
       expect(thirdItem).toBeInTheDocument();
 
-      jest.advanceTimersByTime(1000); // Resolve the first request, should be ignored
+      jest.advanceTimersByTime(1500); // Resolve the first request, should be ignored
 
       firstItem = screen.queryByRole('option', { name: 'first' });
       secondItem = screen.queryByRole('option', { name: 'second' });
@@ -223,6 +229,32 @@ describe('Combobox', () => {
       jest.clearAllTimers();
     });
 
+    it('should debounce requests', async () => {
+      const asyncSpy = jest.fn();
+      const asyncOptions = jest.fn(async () => {
+        return new Promise<ComboboxOption[]>(asyncSpy);
+      });
+
+      render(<Combobox options={asyncOptions} value={null} onChange={onChangeHandler} />);
+
+      const input = screen.getByRole('combobox');
+      await user.click(input);
+
+      expect(asyncSpy).toHaveBeenCalledTimes(1); // Called on open
+      asyncSpy.mockClear();
+
+      await user.keyboard('a');
+      await act(async () => jest.advanceTimersByTime(10));
+
+      await user.keyboard('b');
+      await act(async () => jest.advanceTimersByTime(10));
+
+      await user.keyboard('c');
+      await act(async () => jest.advanceTimersByTime(200));
+
+      expect(asyncSpy).toHaveBeenCalledTimes(1); // Called only for 'abc'
+    });
+
     it('should allow custom value while async is being run', async () => {
       const asyncOptions = jest.fn(async () => {
         return new Promise<ComboboxOption[]>((resolve) => setTimeout(() => resolve([{ value: 'first' }]), 2000));
diff --git a/packages/grafana-ui/src/components/Combobox/Combobox.tsx b/packages/grafana-ui/src/components/Combobox/Combobox.tsx
index 7006ba47182..8204199d151 100644
--- a/packages/grafana-ui/src/components/Combobox/Combobox.tsx
+++ b/packages/grafana-ui/src/components/Combobox/Combobox.tsx
@@ -1,6 +1,7 @@
 import { cx } from '@emotion/css';
 import { useVirtualizer } from '@tanstack/react-virtual';
 import { useCombobox } from 'downshift';
+import { debounce } from 'lodash';
 import { useCallback, useId, useMemo, useState } from 'react';
 
 import { useStyles2 } from '../../themes';
@@ -135,6 +136,24 @@ export const Combobox = <T extends string | number>({
 
   const rowVirtualizer = useVirtualizer(virtualizerOptions);
 
+  const debounceAsync = useMemo(
+    () =>
+      debounce((inputValue: string, customValueOption: ComboboxOption<T> | null) => {
+        loadOptions(inputValue)
+          .then((opts) => {
+            setItems(customValueOption ? [customValueOption, ...opts] : opts);
+            setAsyncLoading(false);
+          })
+          .catch((err) => {
+            if (!(err instanceof StaleResultError)) {
+              // TODO: handle error
+              setAsyncLoading(false);
+            }
+          });
+      }, 200),
+    [loadOptions]
+  );
+
   const {
     getInputProps,
     getMenuProps,
@@ -175,17 +194,7 @@ export const Combobox = <T extends string | number>({
           setItems([customValueOption]);
         }
         setAsyncLoading(true);
-        loadOptions(inputValue)
-          .then((opts) => {
-            setItems(customValueOption ? [customValueOption, ...opts] : opts);
-            setAsyncLoading(false);
-          })
-          .catch((err) => {
-            if (!(err instanceof StaleResultError)) {
-              // TODO: handle error
-              setAsyncLoading(false);
-            }
-          });
+        debounceAsync(inputValue, customValueOption);
 
         return;
       }