Add utility methods for caching valid trees

...through marker files kept in storage under generation regime.

These can be used to allow valid source trees, i.e., those free of
upwards symlinks, to be cached in a persistent manner over multiple
builds.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/buildtool/storage/fs_utils.cpp b/src/buildtool/storage/fs_utils.cpp
index 528dd8dd..861c8728 100644
--- a/src/buildtool/storage/fs_utils.cpp
+++ b/src/buildtool/storage/fs_utils.cpp
@@ -119,6 +119,14 @@ auto GetRehashIDFile(StorageConfig const& storage_config,
            (from_git ? "from-git" : "from-cas") / hash;
 }
 
+auto GetValidTreesMarkerFile(StorageConfig const& storage_config,
+                             std::string const& tree_hash,
+                             std::size_t generation) noexcept
+    -> std::filesystem::path {
+    return storage_config.GenerationCacheRoot(generation) /
+           "validated-git-trees" / tree_hash;
+}
+
 auto WriteTreeIDFile(std::filesystem::path const& tree_id_file,
                      std::string const& tree_id) noexcept -> bool {
     // needs to be done safely, so use the rename trick