_scheduler: Adding Queue.dequeue_ready() to avoid peeking into private queue data

And micro-optimizing the scheduler use a generator expression with any()
to check the result instead of creating a list.

2 files changed, 4 insertions, 1 deletions

diff --git a/buildstream/_scheduler/queue.py b/buildstream/_scheduler/queue.py
index 6aa12af1c..d5f2fd216 100644
--- a/buildstream/_scheduler/queue.py
+++ b/buildstream/_scheduler/queue.py
@@ -176,6 +176,9 @@ class Queue():
         while self.done_queue:
             yield self.done_queue.popleft()
 
+    def dequeue_ready(self):
+        return any(self.done_queue)
+
     def process_ready(self):
         scheduler = self.scheduler
         unready = []
diff --git a/buildstream/_scheduler/scheduler.py b/buildstream/_scheduler/scheduler.py
index 84f538f3d..01df0996b 100644
--- a/buildstream/_scheduler/scheduler.py
+++ b/buildstream/_scheduler/scheduler.py
@@ -345,7 +345,7 @@ class Scheduler():
 
             # process_ready() may have skipped jobs, adding them to the done_queue.
             # Pull these skipped elements forward to the next queue and process them.
-            process_queues = sum([len(q.done_queue) for q in self.queues]) > 0
+            process_queues = any(q.dequeue_ready() for q in self.queues)
 
         # If nothings ticking, time to bail out
         ticking = 0