improve performance and generation of cache.json file

[thescientist13]

Type of Change

• New Feature Request
• Documentation / Website
• Improvement / Suggestion
• Bug
• Other (please clarify below)

Summary

Technical debt tracking for some of the issue rough and dirty technical design decisions made as part of implementing #115 .

Details

Reading and merging / writing cache.json files in serialize.js is a little clunky. For instance, the about route has 4 sub pages, but only needs one cache.json for all of them.

pages.forEach((pagePath) => {
  const contents = fs.readFileSync(pagePath, 'utf-8');
  // TODO hardcoded root / depth - #273
  const pageRoot = pagePath.replace(publicDir, '').split('/')[1];
  const cacheRoot = pageRoot === 'index.html'
    ? ''
    : `${pageRoot}`;
  let cacheContents = {};
  
  // this only needs to be _once_ per page, e.g. about/, docs/
  glob.sync(`${publicDir}/${cacheRoot}/*-cache.json`).forEach((file) => {
    cacheContents = deepmerge(cacheContents, require(file));
  });

  // this (cache.json) also only needs to be done _once_ per page, e.g. about/, docs/
  fs.writeFileSync(`${publicDir}/${cacheRoot}/cache.json`, JSON.stringify(cacheContents));
  fs.writeFileSync(pagePath, contents.replace('___DATA___', JSON.stringify(cacheContents)));
});

In this case, this file would be written 4 times.

[thescientist13]

A naive way could be to simply check if cache.json exists already, and then just not write the file?

const targetFile = `${publicDir}/${cacheRoot}/cache.json`;

if (!fs.existsSync(targetFile) { 
  glob.sync(`${publicDir}/${cacheRoot}/*-cache.json`).forEach((file) => {
    cacheContents = deepmerge(cacheContents, require(file));
  });

  fs.writeFileSync(targetFile, JSON.stringify(cacheContents));
  fs.writeFileSync(pagePath, contents.replace('___DATA___', JSON.stringify(cacheContents)));
}

[thescientist13]

Not valid as per 0.10.0 release.