perf: add performance marker to monitor the needed time for rendering

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

frontend/src/components/common/html-to-react/html-to-react.tsx

@@ -3,6 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { measurePerformance } from '../../../utils/measure-performance'
 import type { ParserOptions } from '@hedgedoc/html-to-react'
 import { convertHtmlToReact } from '@hedgedoc/html-to-react'
 import type DOMPurify from 'dompurify'
@@ -24,8 +25,12 @@ export interface HtmlToReactProps {
  */
 export const HtmlToReact: React.FC<HtmlToReactProps> = ({ htmlCode, domPurifyConfig, parserOptions }) => {
   const elements = useMemo(() => {
-    const sanitizedHtmlCode = sanitize(htmlCode, { ...domPurifyConfig, RETURN_DOM_FRAGMENT: false, RETURN_DOM: false })
+    const sanitizedHtmlCode = measurePerformance('html-to-react: sanitize', () => {
+      return sanitize(htmlCode, { ...domPurifyConfig, RETURN_DOM_FRAGMENT: false, RETURN_DOM: false })
+    })
+    return measurePerformance('html-to-react: convertHtmlToReact', () => {
       return convertHtmlToReact(sanitizedHtmlCode, parserOptions)
+    })
   }, [domPurifyConfig, htmlCode, parserOptions])
 
   return <Fragment>{elements}</Fragment>

frontend/src/components/markdown-renderer/markdown-to-react/markdown-to-react.tsx

@@ -3,6 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { measurePerformance } from '../../../utils/measure-performance'
 import { HtmlToReact } from '../../common/html-to-react/html-to-react'
 import type { MarkdownRendererExtension } from '../extensions/_base-classes/markdown-renderer-extension'
 import { useCombinedNodePreprocessor } from './hooks/use-combined-node-preprocessor'
@@ -43,7 +44,9 @@ export const MarkdownToReact: React.FC<MarkdownToReactProps> = ({
   }, [nodeToReactTransformer, markdownRenderExtensions])
 
   useMemo(() => {
+    measurePerformance('markdown-to-react: update-line-mapping', () => {
       nodeToReactTransformer.setLineIds(lineNumberMapper.updateLineMapping(markdownContentLines))
+    })
   }, [nodeToReactTransformer, lineNumberMapper, markdownContentLines])
 
   const nodePreProcessor = useCombinedNodePreprocessor(markdownRenderExtensions)
@@ -60,7 +63,11 @@ export const MarkdownToReact: React.FC<MarkdownToReactProps> = ({
     [nodeToReactTransformer, nodePreProcessor]
   )
 
-  const html = useMemo(() => markdownIt.render(markdownContentLines.join('\n')), [markdownContentLines, markdownIt])
+  const html = useMemo(() => {
+    return measurePerformance('markdown-to-react: markdown-it', () =>
+      markdownIt.render(markdownContentLines.join('\n'))
+    )
+  }, [markdownContentLines, markdownIt])
   const domPurifyConfig: DOMPurify.Config = useMemo(
     () => ({
       ADD_TAGS: markdownRenderExtensions.flatMap((extension) => extension.buildTagNameAllowList())

frontend/src/utils/measure-performance.spec.ts

@@ -0,0 +1,42 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { measurePerformance } from './measure-performance'
+import { Mock } from 'ts-mockery'
+
+describe('measure performance', () => {
+  it('uses the global performance functions', () => {
+    const measurementName = 'marker-name'
+    const markMock = jest.fn()
+    const measureMock = jest.fn()
+    const startMaker = `${measurementName} - start`
+    const endMarker = `${measurementName} - end`
+
+    Object.defineProperty(window, 'performance', {
+      get: () =>
+        Mock.of<Performance>({
+          mark: markMock,
+          measure: measureMock
+        })
+    })
+    const result = measurePerformance(measurementName, () => {
+      return 'value'
+    })
+    expect(result).toBe('value')
+    expect(markMock).toHaveBeenNthCalledWith(1, startMaker)
+    expect(markMock).toHaveBeenNthCalledWith(2, endMarker)
+    expect(measureMock).toBeCalledWith(measurementName, startMaker, endMarker)
+  })
+
+  it('runs the task without global performance functions', () => {
+    Object.defineProperty(window, 'performance', {
+      get: () => undefined
+    })
+    const result = measurePerformance('measurementName', () => {
+      return 'value'
+    })
+    expect(result).toBe('value')
+  })
+})

frontend/src/utils/measure-performance.ts

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+/**
+ * Uses the browser's performance API to measure how long a given task is running.
+ *
+ * @param measurementName The name of the measurement. Is also used to derive the name of the markers
+ * @param task The task to run
+ * @return the result of the task
+ */
+export const measurePerformance = <T = void>(measurementName: string, task: () => T): T => {
+  if (!window.performance || !window.performance.mark || !window.performance.measure) {
+    return task()
+  }
+  const startMarkName = `${measurementName} - start`
+  const endMarkName = `${measurementName} - end`
+  window.performance.mark(startMarkName)
+  const result = task()
+  window.performance.mark(endMarkName)
+  window.performance.measure(measurementName, startMarkName, endMarkName)
+  return result
+}