[CI] Enabled logging of sccache diagnostics.

Author: PathogenDavid

.github/workflows/ClangSharp.Pathogen.yml

@@ -82,7 +82,8 @@ jobs:
 
       - name: Load LLVM sccache
         id: cached-sccache
-        if: steps.cached-llvm.outputs.cache-hit != 'true'
+        # Always save the (potentially partial) sccache database so it can be used to accelerate subsequent builds when an intermittent failure occurs
+        if: steps.cached-llvm.outputs.cache-hit != 'true' && always()
         uses: actions/cache@v2
         # If you change this configuration make sure to update keep-cache-warm.yml as well.
         with:
@@ -105,8 +106,17 @@ jobs:
         run: ${{matrix.build-command}}
 
       - name: Show sccache statistics
-        if: steps.cached-llvm.outputs.cache-hit != 'true'
-        run: sccache --show-stats
+        if: steps.cached-llvm.outputs.cache-hit != 'true' && always()
+        run: sccache --show-stats 2>&1 | tee ${{steps.sccache.outputs.root-directory}}/sccache-stats.txt
+
+      - name: Save sccache logs
+        uses: actions/upload-artifact@v2
+        if: steps.cached-llvm.outputs.cache-hit != 'true' && always()
+        with:
+          name: llvm-${{matrix.rid}}-sccache-logs
+          path: |
+            ${{steps.sccache.outputs.log-file-path}}
+            ${{steps.sccache.outputs.root-directory}}/sccache-stats.txt
 
       # The GitHub Actions cache gets confused by the symlink so we need to remove it
       - name: Unsymlink libclang

.github/workflows/install-sccache.py

@@ -46,14 +46,18 @@
 # The binary is placed in a subdirectory of its download hash to ensure we don't re-use an old version.
 sccache_root = os.path.join(os.getcwd(), "build-sccache")
 sccache_cache_directory = os.path.join(sccache_root, "cache")
+sccache_cache_log_file_path = os.path.join(sccache_root, "sccache.log")
 
 sccache_directory = os.path.join(sccache_root, expected_hash)
 sccache_binary_location = os.path.join(sccache_directory, binary_name)
 os.makedirs(sccache_directory, exist_ok=True)
 
 # Add sccache to the workspace path and configure sccache's cache directory
 gha.set_output('root-directory', sccache_root)
+gha.set_output('log-file-path', sccache_cache_log_file_path)
 gha.set_environment_variable('SCCACHE_DIR', sccache_cache_directory)
+gha.set_environment_variable('SCCACHE_ERROR_LOG', sccache_cache_log_file_path)
+gha.set_environment_variable('SCCACHE_LOG', 'info')
 gha.add_path(sccache_directory)
 
 # If the output path already exists, no need to download