feat: add fastify cpu profiler server

package.json

@@ -67,6 +67,7 @@
     "fastify-metrics": "^10.2.0",
     "node-pg-migrate": "^6.2.2",
     "pino": "^8.11.0",
-    "postgres": "^3.3.4"
+    "postgres": "^3.3.4",
+    "stacks-encoding-native-js": "^1.0.0"
   }
 }

src/helpers/iterators.ts

@@ -1,3 +1,5 @@
+import * as stream from 'stream';
+import * as util from 'util';
 import { logger } from '../logger';
 import { isDevEnv } from './values';
 
@@ -76,3 +78,6 @@ export async function* asyncIterableToGenerator<T>(iter: AsyncIterable<T>) {
     yield entry;
   }
 }
+
+/** Promisify a pipeline */
+export const pipelineAsync = util.promisify(stream.pipeline);

src/index.ts

@@ -2,5 +2,6 @@ export * from './fastify';
 export * from './helpers';
 export * from './logger';
 export * from './postgres';
+export * from './profiler';
 export * from './server-version';
 export * from './shutdown-handler';

src/profiler/__tests__/profiler.test.ts

@@ -0,0 +1,67 @@
+import { FastifyInstance } from 'fastify';
+import { buildProfilerServer } from '../server';
+import { timeout } from '../../helpers';
+
+describe('CPU profiler', () => {
+  let fastify: FastifyInstance;
+
+  beforeAll(async () => {
+    fastify = await buildProfilerServer();
+  });
+
+  test('CPU profiler snapshot bad duration', async () => {
+    const query1 = await fastify.inject({
+      method: 'GET',
+      url: `/profile/cpu?duration=-100`,
+    });
+    expect(query1.statusCode).toBe(400);
+  });
+
+  test('generate CPU profiler snapshot', async () => {
+    const duration = 0.25; // 250 milliseconds
+    const query1 = await fastify.inject({
+      method: 'GET',
+      url: `/profile/cpu?duration=${duration}`,
+    });
+    expect(query1.statusCode).toBe(200);
+    expect(query1.headers['content-type']).toBe('application/json; charset=utf-8');
+    let cpuProfileBody: any;
+    // Ensure entire profile result was streamed/returned
+    expect(() => {
+      cpuProfileBody = query1.json();
+    }).not.toThrow();
+    // Cursory check for the expected JSON format of a `.cpuprofile` file
+    expect(cpuProfileBody).toEqual(
+      expect.objectContaining({
+        nodes: expect.any(Array),
+        samples: expect.any(Array),
+        timeDeltas: expect.any(Array),
+        startTime: expect.any(Number),
+        endTime: expect.any(Number),
+      })
+    );
+  });
+
+  test('cancel CPU profiler snapshot', async () => {
+    const duration = 150; // 150 seconds
+    // init a cpu profile request, hold on to the promise for reading the request response
+    const promise = fastify.inject({
+      method: 'GET',
+      url: `/profile/cpu?duration=${duration}`,
+    });
+    await timeout(200);
+    // perform a request to cancel the previous profile session
+    const endQuery = await fastify.inject({
+      method: 'GET',
+      url: `/profile/cancel`,
+    });
+    expect(endQuery.statusCode).toBe(200);
+    // ensure the initial request failed
+    const result = await promise;
+    expect(result.statusCode).toBe(500);
+  });
+
+  afterAll(async () => {
+    await fastify.close();
+  });
+});

src/profiler/index.ts

@@ -0,0 +1,2 @@
+export * from './inspector-util';
+export * from './server';