Ability to get more information about cache invalidation?

[PatrickRose]

We're using Github Actions as part of our CI pipeline - and we're using cache/restore and cache/save to make sure subsequent builds are faster.

However, what we're finding is that the first run on a PR runs slowly (and PHPStan appears to do a full analysis), even though it's restored the cache item from the main branch (which I've confirmed with --fail-without-result-cache). In that case I'd expect it to only rerun the analysis of changed files from the main branch, but it seems that isn't happening.

Is there a way I can find out which "expiration" rule PHPStan has triggered?

[ondrejmirtes]

Hello, you can get the rough idea what's different if you run with -vvv. It will produce output like:

Result cache not used because the metadata do not match: phpstanVersion, projectConfig, composerLocks, composerInstalled

To inspect the exact differences, you should download the restored cache file, and also the new produced file after the run, and diff them. That will tell you exactly why PHPStan didn't use it.

[ondrejmirtes]

Also make sure you're using GitHub Actions' cache correctly, with something like:

  - name: "Restore result cache"
    uses: actions/cache/restore@v3
    with:
      path: ./tmp
      key: "result-cache-v1-${{ matrix.php-version }}-${{ github.run_id }}"
      restore-keys: |
        result-cache-v1-${{ matrix.php-version }}-

  # … run phpstan

  - name: "Save result cache"
    uses: actions/cache/save@v3
    if: always()
    with:
      path: ./tmp
      key: "result-cache-v1-${{ matrix.php-version }}-${{ github.run_id }}"

(from https://staabm.github.io/2023/10/21/phpstan-result-cache-gotchas.html)