cascache: parse timestamp and update mtimes in checkout

If checking out files from a CasBasedDirectory which holds
node_properties in the index files are explicitly copied instead of
being hardlinked and the mtime is updated to the stored value.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/buildstream/_cas/cascache.py b/src/buildstream/_cas/cascache.py
index 519de6e2e..bb2abc6c8 100644
--- a/src/buildstream/_cas/cascache.py
+++ b/src/buildstream/_cas/cascache.py
@@ -217,10 +217,18 @@ class CASCache:
         for filenode in directory.files:
             # regular file, create hardlink
             fullpath = os.path.join(dest, filenode.name)
-            if can_link:
+            # generally, if the node holds properties we will fallback
+            # to copying instead of hardlinking
+            if can_link and not filenode.node_properties:
                 utils.safe_link(self.objpath(filenode.digest), fullpath)
             else:
                 utils.safe_copy(self.objpath(filenode.digest), fullpath)
+                if filenode.node_properties:
+                    # see https://github.com/bazelbuild/remote-apis/blob/master/build/bazel/remote/execution/v2/nodeproperties.md
+                    # for supported node property specifications
+                    for prop in filenode.node_properties:
+                        if prop.name == "MTime" and prop.value:
+                            utils._set_file_mtime(fullpath, utils._parse_timestamp(prop.value))
 
             if filenode.is_executable:
                 os.chmod(