feat(gatsby-plugin-sharp): cache image metadata

[ascorbic]

Description

Caches image metadata between builds

Documentation

Currently gatsby-plugin-sharp uses an in-memory cache to store image metadata during a build, but it is not persisted between builds. This means that the relatively expensive dominant color calculations need to be re-done each time. This PR switches to use the GatsbyCache if it is available, falling back to the in-memory cache otherwise. In my tests, this saved over a minute for warm-cache builds of a site with 100 images.

Related Issues

[pieh]

Nice!

[ascorbic]

Thanks! I'll investigate what's going on with the development runtime tests and see if I can reproduce locally

[LekoArts]

The development/production have some flaky tests, I've restarted them and let's see

[ascorbic]

They failed when I opened the PR which I assumed was flakiness, but failed again today when @pieh restarted them, so I think it may be real

[ascorbic]

They're all failing on hot-reloading/new-file.js, which seems unlikely to be related. I'm failing to get them running properly on my machine

[LekoArts]

Yeah, hot-reloading/new-file.js is unrelated, I fixed this in https://github.com/gatsbyjs/gatsby/pull/35730/files#diff-b1afd70a3b70f0af3ded5b10840884a6563ba768424b5390b9dcf0ffac753ccf

[ascorbic]

Aha. Another PR failing with the same test. Must be unrelated.

[LekoArts]

But in https://app.circleci.com/pipelines/github/gatsbyjs/gatsby/82992/workflows/a0fe5b63-96e0-491f-ae20-9b68f4732e5d/jobs/988774 the gatsby-plugin-image.js one fails

[ascorbic]

Hah. Jinx. OK, so should this wait til that fix lands?

[ascorbic]

Hmm. I don't understand what's happening with that one: https://dashboard.cypress.io/projects/5k8zbj/runs/641/overview/ee804400-e764-4d86-a9a5-362aae24bdab

[ascorbic]

I've pushed another commit with that ({ force: true }) change, just to see if the tests then pass

[LekoArts]

Published at next 👍

[ascorbic]

I have another optimisation coming in shortly

[ascorbic]

@LekoArts #35814