From ea86754aa61910f93786aef8f388b4cc4220dc9f Mon Sep 17 00:00:00 2001
From: Matthieu Riegler <kyro38@gmail.com>
Date: Mon, 3 Jun 2024 21:16:33 +0200
Subject: [PATCH] refactor(platform-server): Add private profiler. (#56274)

The commit adds a private profiler to investigate SSR performance.

PR Close #56274
---
 .../platform-server/src/private_export.ts     |  4 ++
 packages/platform-server/src/profiler.ts      | 64 +++++++++++++++++++
 packages/platform-server/src/utils.ts         | 14 ++--
 3 files changed, 78 insertions(+), 4 deletions(-)
 create mode 100644 packages/platform-server/src/profiler.ts

diff --git a/packages/platform-server/src/private_export.ts b/packages/platform-server/src/private_export.ts
index b3749f03276..d778507975d 100644
--- a/packages/platform-server/src/private_export.ts
+++ b/packages/platform-server/src/private_export.ts
@@ -11,3 +11,7 @@ export {
   SERVER_RENDER_PROVIDERS as ɵSERVER_RENDER_PROVIDERS,
 } from './server';
 export {SERVER_CONTEXT as ɵSERVER_CONTEXT} from './utils';
+export {
+  enableSsrProfiling as ɵenableSsrProfiling,
+  disableSsrProfiling as ɵdisableSsrProfiling,
+} from './profiler';
diff --git a/packages/platform-server/src/profiler.ts b/packages/platform-server/src/profiler.ts
new file mode 100644
index 00000000000..1ee2a8f423c
--- /dev/null
+++ b/packages/platform-server/src/profiler.ts
@@ -0,0 +1,64 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+const PERFORMANCE_MARK_PREFIX = '🅰️';
+
+let enablePerfLogging = false;
+
+export function runAndMeasurePerf<T>(label: string, method: () => T): T {
+  if (!enablePerfLogging) {
+    return method();
+  }
+
+  const labelName = `${PERFORMANCE_MARK_PREFIX}:${label}`;
+  const startLabel = `start:${labelName}`;
+  const endLabel = `end:${labelName}`;
+
+  const end = () => {
+    /* tslint:disable:ban */
+    performance.mark(endLabel);
+    performance.measure(labelName, startLabel, endLabel);
+    performance.clearMarks(startLabel);
+    performance.clearMarks(endLabel);
+    /* tslint:enable:ban */
+  };
+
+  /* tslint:disable:ban */
+  performance.mark(startLabel);
+  /* tslint:enable:ban */
+
+  const returnValue = method();
+  if (returnValue instanceof Promise) {
+    return returnValue.finally(() => end()) as T;
+  } else {
+    end();
+    return returnValue;
+  }
+}
+
+let warningLogged = false;
+/**
+ * This enables an internal performance profiler for SSR apps
+ *
+ * It should not be imported in application code
+ */
+export function enableSsrProfiling() {
+  if (
+    !warningLogged &&
+    (typeof performance === 'undefined' || !performance.mark || !performance.measure)
+  ) {
+    warningLogged = true;
+    console.warn('Performance API is not supported on this platform');
+    return;
+  }
+
+  enablePerfLogging = true;
+}
+export function disableSsrProfiling() {
+  enablePerfLogging = false;
+}
diff --git a/packages/platform-server/src/utils.ts b/packages/platform-server/src/utils.ts
index a52be9f50c5..b7a2e3c09ff 100644
--- a/packages/platform-server/src/utils.ts
+++ b/packages/platform-server/src/utils.ts
@@ -26,6 +26,7 @@ import {PlatformState} from './platform_state';
 import {platformServer} from './server';
 import {BEFORE_APP_SERIALIZED, INITIAL_CONFIG} from './tokens';
 import {createScript} from './transfer_state';
+import {runAndMeasurePerf} from './profiler';
 
 /**
  * Event dispatch (JSAction) script is inlined into the HTML by the build
@@ -145,7 +146,9 @@ function insertEventRecordScript(
     // This is defined in packages/core/primitives/event-dispatch/contract_binary.ts
     const replayScriptContents = `window.__jsaction_bootstrap('ngContracts', document.body, ${JSON.stringify(
       appId,
-    )}, ${JSON.stringify(Array.from(regular))}${capture.size ? ',' + JSON.stringify(Array.from(capture)) : ''});`;
+    )}, ${JSON.stringify(Array.from(regular))}${
+      capture.size ? ',' + JSON.stringify(Array.from(capture)) : ''
+    });`;
 
     const replayScript = createScript(doc, replayScriptContents, nonce);
 
@@ -272,7 +275,10 @@ export async function renderApplication<T>(
   bootstrap: () => Promise<ApplicationRef>,
   options: {document?: string | Document; url?: string; platformProviders?: Provider[]},
 ): Promise<string> {
-  const platformRef = createServerPlatform(options);
-  const applicationRef = await bootstrap();
-  return _render(platformRef, applicationRef);
+  return runAndMeasurePerf('renderApplication', async () => {
+    const platformRef = createServerPlatform(options);
+
+    const applicationRef = await bootstrap();
+    return _render(platformRef, applicationRef);
+  });
 }