feat(server): add config option to define etag hash function

[pimlie]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

While looking into some benchmarks, @aldarund found out that generating the etag could snoop up a lot of processing time (especially with large html, ie extractCss: false). Further investigation found that the etag module uses SHA1 for generating a hash of the full html body.

This pr introduces a new config option render.etag.hash which users can use to implement their own etag hash function. Ie for etags it should often be fine to use a non-cryptographic hash function like murmurhash, which is multiple times faster with larger html body sizes.

Note: the render.etag.weak option is ignored when using the hook, user is responsible for implementing that.

Example for using murmurhash-native instead:

// nuxt.config.js
import { murmurHash128 } from 'murmurhash-native'

export default {
  render: {
    etag: {
      hash: html => murmurHash128(html)
    }
  }
}

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[codecov-io]

Codecov Report

Merging #6438 into dev will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             dev    #6438      +/-   ##
=========================================
+ Coverage   95.6%   95.61%   +0.01%     
=========================================
  Files         79       79              
  Lines       2684     2693       +9     
  Branches     692      697       +5     
=========================================
+ Hits        2566     2575       +9     
  Misses       101      101              
  Partials      17       17

Flag	Coverage Δ
#e2e	100% <ø> (ø)	⬆️
#fixtures	50.64% <30%> (-0.06%)	⬇️
#unit	92.31% <100%> (+0.02%)	⬆️

Impacted Files	Coverage Δ
packages/config/src/options.js	100% <100%> (ø)	⬆️
packages/server/src/middleware/nuxt.js	97.36% <100%> (+0.03%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 75f8564...bbb5dc1. Read the comment docs.