CI: caching: add early termination

Author: Anton-Latukha

.github/workflows/caching.yml

@@ -139,6 +139,7 @@ jobs:
           restore-keys: ${{ env.cache-name }}-
 
       - name: Compiled deps cache
+        id: compiled-deps
         uses: actions/cache@v2
         env:
           cache-name: compiled-deps
@@ -150,9 +151,12 @@ 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
 
@@ -161,7 +165,8 @@ 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