sccache sudo

dev/ci/setup-sccache

@@ -43,6 +43,24 @@ for PROG in cc c++; do
 done
 
 
+## Update environment variables.
+
+HAS_SCCACHE_IN_PATH=$(ruby -e 'puts ENV["PATH"].split(":").include?("/usr/local/bin")')
+if !$HAS_SCCACHE_IN_PATH; then
+    echo "PATH=/usr/local/bin:$PATH" >> "$GITHUB_ENV"
+fi
+
+HAS_COMPILER_WRAPPERS_IN_PATH=$(ruby -e 'puts ENV["PATH"].split(":").include?("/usr/local/libexec/sccache")')
+if ! $HAS_COMPILER_WRAPPERS_IN_PATH; then
+    echo "PATH=/usr/local/libexec/sccache:/usr/local/bin:$PATH" >> "$GITHUB_ENV"
+else
+    # When starting the sccache server, the compiler wrappers must *not* be in PATH
+    # so that the sccache server uses the non-wrapped compilers.
+    PATH=$(ruby -e 'paths = ENV["PATH"].split(":"); paths.delete("/usr/local/libexec/sccache"); puts paths.join(":")')
+    export PATH
+fi
+
+
 ## Start sccache server.
 
 ## Uncomment this to have the sccache server write debug logs to sccache.log.
@@ -58,5 +76,8 @@ else
     env SCCACHE_START_SERVER=1 sccache
 fi
 
-# Give sccache server some time to start.
-sleep 0.5
+echo "Waiting until sccache server is started..."
+while [[ -z "$(cat sccache.log)" ]]; then
+    sleep 0.1
+fi
+echo "sccache server is started."