CI: prevent moc from running in cache population step (#29401)

* Do not remove moc_files from cache

* Add cache cleanup script

* Use cache cleanup script

* Dry-run in cache population command

* Add newline

* Temporarly disable master only constraint for cache cleanup step

* Add test lines

* one more

* Fix shebang

* Remove debug lines

* Bring back master branch constraints

.github/workflows/selfdrive_tests.yaml

@@ -82,9 +82,8 @@ jobs:
       run: ${{ env.RUN }} "scons -j$(nproc) --extras && release/check-dirty.sh"
     - name: Cleanup scons cache and rebuild
       timeout-minutes: ${{ ((steps.restore-scons-cache.outputs.cache-hit == 'true') && 2 || 30) }} # allow more time when we missed the scons cache
-      run: |
+      if: github.ref == 'refs/heads/master'
-          ${{ env.RUN }} "rm -rf /tmp/scons_cache/* && \
+      run: ${{ env.RUN }} "release/clean-cache.sh"
-                          scons -j$(nproc) --cache-populate"
     - name: Save scons cache
       uses: actions/cache/save@v3
       if: github.ref == 'refs/heads/master'
@@ -159,9 +158,8 @@ jobs:
     - name: Pre Cache - Cleanup scons cache
       if: github.ref == 'refs/heads/master'
       run: |
-        rm -rf /tmp/scons_cache/*
         eval "$(pyenv init --path)"
-        poetry run scons -j$(nproc) --cache-populate
+        poetry run release/clean-cache.sh
     - name: Save scons cache
       id: scons-save-cache
       uses: actions/cache/save@v3

release/clean-cache.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -e
+
+# delete outdated moc files
+scons --dry-run --taskmastertrace /tmp/tasktrace.log >/dev/null
+MOC_EXISTING_PROD="$(find /tmp/scons_cache/moc_files -type f | sort)"
+MOC_CURRENT_PROD="$(egrep -o "'[^']*moc_files[^']*'" /tmp/tasktrace.log | sed  "s/'//g" | sort | uniq)"
+MOC_JUNK="$(comm -23 <(echo "$MOC_EXISTING_PROD") <(echo "$MOC_CURRENT_PROD"))"
+echo "$MOC_JUNK" | xargs -I{} rm {}
+rm /tmp/tasktrace.log
+
+# delete cache except for moc files
+rm -rf $(find /tmp/scons_cache -maxdepth 1 ! -name moc_files ! -name scons_cache)
+
+# repopulate cache 
+scons --dry-run --cache-populate >/dev/null