Move fetch logic from FetchQueue to Element

The queue shouldn't need to know about individual sources. This is in
line with _track() and _get_consistency().

2 files changed, 14 insertions, 4 deletions

diff --git a/buildstream/_scheduler/queues/fetchqueue.py b/buildstream/_scheduler/queues/fetchqueue.py
index 446dbbd3b..c58bfdb57 100644
--- a/buildstream/_scheduler/queues/fetchqueue.py
+++ b/buildstream/_scheduler/queues/fetchqueue.py
@@ -40,10 +40,7 @@ class FetchQueue(Queue):
         self._skip_cached = skip_cached
 
     def process(self, element):
-        previous_sources = []
-        for source in element.sources():
-            source._fetch(previous_sources)
-            previous_sources.append(source)
+        element._fetch()
 
     def status(self, element):
         # state of dependencies may have changed, recalculate element state
diff --git a/buildstream/element.py b/buildstream/element.py
index e44a7cc32..e9a0f6f65 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -2022,6 +2022,19 @@ class Element(Plugin):
 
         return True
 
+    # _fetch()
+    #
+    # Fetch the element's sources.
+    #
+    # Raises:
+    #    SourceError: If one of the element sources has an error
+    #
+    def _fetch(self):
+        previous_sources = []
+        for source in self.sources():
+            source._fetch(previous_sources)
+            previous_sources.append(source)
+
     #############################################################
     #                   Private Local Methods                   #
     #############################################################