From 740bf073b2bec66b36c2fc685556eb3d80b5df90 Mon Sep 17 00:00:00 2001
From: Pooya Parsa <pyapar@gmail.com>
Date: Sun, 15 Nov 2020 01:52:18 +0100
Subject: [PATCH] feat: timing plugin and Server-Timing

---
 packages/nitro/src/config.ts        |  4 ++--
 packages/nitro/src/rollup/config.ts |  8 ++++----
 packages/nitro/src/rollup/timing.ts | 31 +++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 6 deletions(-)
 create mode 100644 packages/nitro/src/rollup/timing.ts

diff --git a/packages/nitro/src/config.ts b/packages/nitro/src/config.ts
index 6a2c05f7ab..5fdef9687d 100644
--- a/packages/nitro/src/config.ts
+++ b/packages/nitro/src/config.ts
@@ -37,7 +37,7 @@ export interface SLSOptions {
   minify: boolean
   externals: boolean
   rollupConfig?: any
-  logStartup: boolean
+  timing: boolean
   inlineChunks: boolean
   renderer: string
   analyze: boolean
@@ -72,7 +72,7 @@ export function getoptions (nuxtOptions: Nuxt['options'], serverless: SLSConfig)
     staticAssets: nuxtOptions.generate.staticAssets,
 
     outName: '_nuxt.js',
-    logStartup: true,
+    timing: true,
     inlineChunks: true,
     minify: false,
     externals: false,
diff --git a/packages/nitro/src/rollup/config.ts b/packages/nitro/src/rollup/config.ts
index d63328d374..71dce30371 100644
--- a/packages/nitro/src/rollup/config.ts
+++ b/packages/nitro/src/rollup/config.ts
@@ -14,8 +14,10 @@ import analyze from 'rollup-plugin-analyzer'
 import hasha from 'hasha'
 import { SLSOptions } from '../config'
 import { resolvePath, MODULE_DIR } from '../utils'
+
 import { dynamicRequire } from './dynamic-require'
 import { externals } from './externals'
+import { timing } from './timing'
 
 const mapArrToVal = (val, arr) => arr.reduce((p, c) => ({ ...p, [c]: val }), {})
 
@@ -107,10 +109,8 @@ export const getRollupConfig = (options: SLSOptions) => {
     plugins: []
   }
 
-  if (options.logStartup) {
-    rollupConfig.output.intro += 'global._startTime = global.process.hrtime();'
-    // eslint-disable-next-line no-template-curly-in-string
-    rollupConfig.output.outro += 'global._endTime = global.process.hrtime(global._startTime); global._coldstart = ((global._endTime[0] * 1e9) + global._endTime[1]) / 1e6; console.log(`λ Cold start took: ${global._coldstart}ms (${typeof __filename !== "undefined" ? __filename.replace(process.cwd(), "") : "<entry>"})`);'
+  if (options.timing) {
+    rollupConfig.plugins.push(timing())
   }
 
   // https://github.com/rollup/plugins/tree/master/packages/replace
diff --git a/packages/nitro/src/rollup/timing.ts b/packages/nitro/src/rollup/timing.ts
new file mode 100644
index 0000000000..97b26f1e53
--- /dev/null
+++ b/packages/nitro/src/rollup/timing.ts
@@ -0,0 +1,31 @@
+import { extname } from 'path'
+import type { Plugin, RenderedChunk } from 'rollup'
+
+export interface Options { }
+
+const TIMING = 'global.__timing__'
+
+const iife = code => `(function() { ${code.trim()} })();`.replace(/\n/g, '')
+
+const HELPER = TIMING + '=' + iife(`
+const hrtime = global.process.hrtime;
+const start = () => hrtime();
+const end = s => { const d = hrtime(s); return ((d[0] * 1e9) + d[1]) / 1e6; };
+
+const _s = {};
+const metrics = [];
+const logStart = id => { _s[id] = hrtime(); };
+const logEnd = id => { const t = end(_s[id]); delete _s[id]; metrics.push([id, t]); console.log('◈', id, t, 'ms'); };
+return { hrtime, start, end, metrics, logStart, logEnd };
+`)
+
+export function timing (_opts: Options = {}): Plugin {
+  return {
+    name: 'timing',
+    renderChunk (code, chunk: RenderedChunk) {
+      let name = chunk.fileName || ''
+      name = name.replace(extname(name), '')
+      return "'use strict';" + HELPER + `${TIMING}.logStart('import:${name}');` + code + `;${TIMING}.logEnd('import:${name}');`
+    }
+  }
+}