From c1ce6c215743853ade5f0d65e2b2b55addc0ce2c Mon Sep 17 00:00:00 2001
From: Anton Golub <antongolub@antongolub.com>
Date: Thu, 10 Nov 2022 14:15:59 +0300
Subject: [PATCH] perf: avoid redundant buffers init

---
 src/main/js/firewall/middleware.js | 11 +++++++----
 src/main/js/firewall/packument.js  | 12 +++++-------
 src/main/js/util.js                |  2 ++
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/main/js/firewall/middleware.js b/src/main/js/firewall/middleware.js
index af60bc2..9141301 100644
--- a/src/main/js/firewall/middleware.js
+++ b/src/main/js/firewall/middleware.js
@@ -1,7 +1,8 @@
+import {Buffer} from 'node:buffer'
 import {httpError, NOT_FOUND, ACCESS_DENIED, METHOD_NOT_ALLOWED, NOT_MODIFIED, OK, FOUND} from '../http/index.js'
 import {getPolicy, getPipeline} from './engine.js'
 import {getPackument} from './packument.js'
-import {normalizePath, gunzip, dropNullEntries, time} from '../util.js'
+import {normalizePath, gzip, dropNullEntries, time, jsonBuffer} from '../util.js'
 import {hasHit, hasKey, isNoCache} from '../cache.js'
 import {getCtx} from '../als.js'
 import {checkTarball} from './tarball.js'
@@ -60,14 +61,14 @@ export const firewall = ({registry, rules, entrypoint: _entrypoint, token}) => a
 
   warmupPipeline(pipeline, boundContext)
   const [
-    { packumentBuffer, headers, etag, deps, directives },
+    { packument, packumentBufferZip, headers, etag, deps, directives },
     tarball
   ] = await Promise.all([
     getPackument({ boundContext, rules }),
     version ? checkTarball({registry, url: req.url}) : Promise.resolve(false)
   ])
 
-  if (!packumentBuffer) {
+  if (!packument) {
     return next(httpError(NOT_FOUND))
   }
 
@@ -95,7 +96,9 @@ export const firewall = ({registry, rules, entrypoint: _entrypoint, token}) => a
 
   // Packument request
   const isGzip = req.headers['accept-encoding']?.includes('gzip')
-  const buffer = isGzip ? packumentBuffer : await time(gunzip, `gunzip packument ${name}`)(packumentBuffer)
+  const buffer = isGzip
+    ? packumentBufferZip || await time(gzip, `gzip packument ${name}`)(jsonBuffer(packument))
+    : jsonBuffer(packument)
   const cl = '' + buffer.length
   const extra = isGzip
     ? {'content-length': cl, 'transfer-encoding': null, 'content-encoding': 'gzip', etag}
diff --git a/src/main/js/firewall/packument.js b/src/main/js/firewall/packument.js
index 2e4cfb3..fb1b5e3 100644
--- a/src/main/js/firewall/packument.js
+++ b/src/main/js/firewall/packument.js
@@ -1,4 +1,3 @@
-import {Buffer} from 'node:buffer'
 import crypto from 'node:crypto'
 
 import {getDirectives, getPolicy} from './engine.js'
@@ -25,14 +24,13 @@ export const getPackument = async ({boundContext, rules}) => {
   const deps = getDeps(packument)
   const directives = await getDirectives({ packument, rules, boundContext})
   const _packument = patchPackument({ packument, directives, entrypoint, registry })
+  const vkeys = Object.keys(_packument.versions)
 
-  if (Object.keys(_packument.versions).length === 0) {
+  if (vkeys.length === 0) {
     return {}
   }
-  const packumentBuffer = Object.keys(_packument.versions).length === Object.keys(packument.versions).length
-    ? buffer
-    : Buffer.from(JSON.stringify(_packument))
-  const etag = 'W/' + JSON.stringify(crypto.createHash('sha256').update(packumentBuffer.slice(0, 65_536)).digest('hex'))
+  const packumentBufferZip = vkeys.length === Object.keys(packument.versions).length && buffer
+  const etag = 'W/' + JSON.stringify(crypto.createHash('sha256').update(`${packument.name}${vkeys.join(',')}`).digest('hex'))
 
   return {
     etag,
@@ -40,7 +38,7 @@ export const getPackument = async ({boundContext, rules}) => {
     directives,
     headers,
     packument: _packument,
-    packumentBuffer,
+    packumentBufferZip,
   }
 }
 
diff --git a/src/main/js/util.js b/src/main/js/util.js
index c209e53..1c3f346 100644
--- a/src/main/js/util.js
+++ b/src/main/js/util.js
@@ -198,3 +198,5 @@ export const time = (fn, label = fn.name) => async (...args) => {
 }
 
 export const setFnName = (fn, name) => Object.defineProperty(fn, 'name', { value: name })
+
+export const jsonBuffer = (v) => Buffer.from(JSON.stringify(v))