Merge pull request #521 from netlify/fix_rust_cache

Fix Rust caching issues

run-build-functions.sh

@@ -675,7 +675,11 @@ cache_artifacts() {
   cache_cwd_directory ".venv" "python virtualenv"
   cache_cwd_directory ".build" "swift build"
   cache_cwd_directory ".netlify/plugins" "build plugins"
-  cache_cwd_directory "target" "rust compile output"
+
+  if [ -f Cargo.toml ] || [ -f Cargo.lock ]
+  then
+    cache_cwd_directory_fast_copy "target" "rust compile output"
+  fi
 
   cache_home_directory ".yarn_cache" "yarn cache"
   cache_home_directory ".cache/pip" "pip cache"
@@ -686,8 +690,12 @@ cache_artifacts() {
   cache_home_directory ".composer" "composer dependencies"
   cache_home_directory ".homebrew-cache", "homebrew cache"
   cache_home_directory ".rustup" "rust rustup cache"
-  cache_home_directory ".cargo/registry" "rust cargo registry cache"
-  cache_home_directory ".cargo/bin" "rust cargo bin cache"
+
+  if [ -f Cargo.toml ] || [ -f Cargo.lock ]
+  then
+    cache_home_directory ".cargo/registry" "rust cargo registry cache"
+    cache_home_directory ".cargo/bin" "rust cargo bin cache"
+  fi
 
   # Don't follow the Go import path or we'll store
   # the origin repo twice.
@@ -748,6 +756,17 @@ move_cache() {
   fi
 }
 
+fast_copy_cache() {
+  local src=$1
+  local dst=$2
+  if [ -d $src ]
+  then
+    echo "Started $3"
+    cp --reflink=always $src $dst
+    echo "Finished $3"
+  fi
+}
+
 restore_home_cache() {
   move_cache "$NETLIFY_CACHE_DIR/$1" "$HOME/$1" "restoring cached $2"
 }
@@ -764,6 +783,10 @@ cache_cwd_directory() {
   move_cache "$PWD/$1" "$NETLIFY_CACHE_DIR/$1" "saving $2"
 }
 
+cache_cwd_directory_fast_copy() {
+  fast_copy_cache "$PWD/$1" "$NETLIFY_CACHE_DIR/$1" "saving $2"
+}
+
 install_missing_commands() {
   if [[ $BUILD_COMMAND_PARSER == *"grunt"* ]]
   then