element.py: Alter Element.__calculate_cache_key() to pre-santize inputsdanielsilverstone-ct/saved-for-later

In order to reduce the effort we spend in `_yaml.node_sanitize()` take
advantage of how `OrderedDict` works and pre-sanitize the majority of
the cache-key once.  This approximately halves the amount of effort we
spend in `_yaml.node_sanitize()` in pre-scheduler build scenarios.

Signed-off-by: Daniel Silverstone <daniel.silverstone@codethink.co.uk>

1 files changed, 6 insertions, 3 deletions

diff --git a/buildstream/element.py b/buildstream/element.py
index a243826ed..f7b226cdd 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -2108,11 +2108,14 @@ class Element(Plugin):
             }
 
             self.__cache_key_dict['fatal-warnings'] = sorted(project._fatal_warnings)
+            self.__cache_key_dict['dependencies'] = []
+            self.__cache_key_dict = _yaml.node_sanitize(self.__cache_key_dict)
 
-        cache_key_dict = self.__cache_key_dict.copy()
-        cache_key_dict['dependencies'] = dependencies
+        # This replacement is safe since OrderedDict replaces the value,
+        # leaving its location in the dictionary alone.
+        self.__cache_key_dict['dependencies'] = _yaml.node_sanitize(dependencies)
 
-        return _cachekey.generate_key(cache_key_dict)
+        return _cachekey.generate_key_pre_sanitized(self.__cache_key_dict)
 
     # __can_build_incrementally()
     #