CI: caching: add early termination & run check on schedule (haskell#2506)

* CI: caching: add early termination * CI: caching: run cache check 3 times a day Recently there is a lot of PRs/builds from internal repo branches. Repo cache has 10G pool limit & PR caches are not shared between PRs, but main branch cache is. Checking & when missing rebuilding it ensures that if internal branch PRs pushed main state out of the pool - it gets reinstituted. *afaik* there is no way to prioritize main branch cache better, since GitHub CI FIFO caches out of the pool by build time. Co-authored-by: Javier Neira <atreyu.bbb@gmail.com> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: 3 people

.github/workflows/caching.yml

@@ -30,6 +30,18 @@ on:
  push:
  branches:
  - master
+ schedule:
+ # Refresh snapshot every (02+8*x):25 UTC
+ # When cache is present it is a light check workflow with early termination.
+ # When primary cache is not hit - runs the cache generation.
+ # Why: GitHub repo has 10G pool & on overflow GitHub removes caches in FIFO manner.
+ # When internal branche PRs save into the same pool -
+ # their cache is accessible only inside of the scope of the PR.
+ # If main cache is forced out - there are no cache shared between PRs,
+ # which implies all PRs would start to create & save their cache.
+ # Reinstitution of the main chache puts it back into FIFO
+ # & so it gets shared across all PRs.
+ - cron: "25 2/8 * * *"
 
 env:
  cabalBuild: "v2-build all --enable-tests --enable-benchmarks"
@@ -130,6 +142,7 @@ jobs:
  restore-keys: ${{ env.cache-name }}-
 
  - name: Compiled deps cache
+ id: compiled-deps
  uses: actions/cache@v2
  env:
  cache-name: compiled-deps
@@ -141,9 +154,12 @@ jobs:
  ${{ env.cache-name }}-${{ runner.os }}-${{ matrix.ghc }}-
  ${{ env.cache-name }}-${{ runner.os }}-
 
- - run: cabal update
+ - if: (! steps.compiled-deps.outputs.cache-hit)
+ run: |
+ cabal update
 
- - name: Download all sources
+ - if: (! steps.compiled-deps.outputs.cache-hit)
+ name: Download all sources
  run: |
  cabal $cabalBuild --only-download
 
@@ -152,7 +168,8 @@ jobs:
  # but to cache what can be cached, so step is fault tolerant & would always succseed.
  # 2021-12-11: NOTE: Building all targets, since
  # current Cabal does not allow `all --enable-tests --enable-benchmarks --only-dependencies`
- - name: Build all targets; try 3 times
+ - if: (! steps.compiled-deps.outputs.cache-hit)
+ name: Build all targets; try 3 times
  continue-on-error: true
  run: |
  cabal $cabalBuild || cabal $cabalBuild || cabal $cabalBuild