pullqueue.py: Wait for cache to become queryable

Wait for cache to become queryable instead of simply skipping the
element.

1 files changed, 7 insertions, 0 deletions

diff --git a/buildstream/_scheduler/pullqueue.py b/buildstream/_scheduler/pullqueue.py
index 3ab5ab7f4..38de9cf09 100644
--- a/buildstream/_scheduler/pullqueue.py
+++ b/buildstream/_scheduler/pullqueue.py
@@ -39,6 +39,13 @@ class PullQueue(Queue):
         return element._pull()
 
     def status(self, element):
+        # state of dependencies may have changed, recalculate element state
+        element._update_state()
+
+        # cache cannot be queried until strict cache key is available
+        if element._get_strict_cache_key() is None:
+            return QueueStatus.WAIT
+
         if element._cached(strength=_KeyStrength.STRONG):
             return QueueStatus.SKIP
         elif element._remotely_cached(strength=_KeyStrength.STRONG):