Assign multiple pending tasks in one go

cncd/queue/fifo.go

@@ -59,9 +59,7 @@ func (q *fifo) PushAtOnce(c context.Context, tasks []*Task) error {
 		q.pending.PushBack(task)
 	}
 	q.Unlock()
-	for range tasks {
-		go q.process()
-	}
+	go q.process()
 	return nil
 }
 
@@ -107,7 +105,6 @@ func (q *fifo) Error(c context.Context, id string, err error) error {
 		q.removeFromPending(id)
 	}
 	q.Unlock()
-	go q.process()
 	return nil
 }
 
@@ -194,8 +191,21 @@ func (q *fifo) process() {
 
 	q.resubmitExpiredBuilds()
 
+	for pending, worker := q.assignToWorker(); pending != nil && worker != nil; pending, worker = q.assignToWorker() {
+		task := pending.Value.(*Task)
+		delete(q.workers, worker)
+		q.pending.Remove(pending)
+		q.running[task.ID] = &entry{
+			item:     task,
+			done:     make(chan bool),
+			deadline: time.Now().Add(q.extension),
+		}
+		worker.channel <- task
+	}
+}
+
+func (q *fifo) assignToWorker() (*list.Element, *worker) {
 	var next *list.Element
-loop:
 	for e := q.pending.Front(); e != nil; e = next {
 		next = e.Next()
 		task := e.Value.(*Task)
@@ -204,23 +214,16 @@ loop:
 			logrus.Debugf("queue: skipping due to unmet dependencies %v", task.ID)
 			continue
 		}
+
 		for w := range q.workers {
 			if w.filter(task) {
-				delete(q.workers, w)
-				q.pending.Remove(e)
-
-				q.running[task.ID] = &entry{
-					item:     task,
-					done:     make(chan bool),
-					deadline: time.Now().Add(q.extension),
-				}
-
 				logrus.Debugf("queue: assigned task: %v with deps %v", task.ID, task.Dependencies)
-				w.channel <- task
-				break loop
+				return e, w
 			}
 		}
 	}
+
+	return nil, nil
 }
 
 func (q *fifo) resubmitExpiredBuilds() {