kvserver: add PriorityInversionRequeue

This commit adds a new cluster setting PriorityInversionRequeue that controls
whether the replicate queue should requeue replicas when their priority at
enqueue time differs significantly from their priority at processing time
(e.g. dropping from top 3 to the lowest priority).

Author: wenyihu6

pkg/kv/kvserver/replicate_queue.go

@@ -101,6 +101,19 @@ var EnqueueProblemRangeInReplicateQueueInterval = settings.RegisterDurationSetti
 	0,
 )
 
+// TODO(wenyihu6): move these cluster settings to kvserverbase
+
+// PriorityInversionRequeue is a setting that controls whether to requeue
+// replicas when their priority at enqueue time and processing time is inverted
+// too much (e.g. dropping from a repair action to AllocatorConsiderRebalance).
+var PriorityInversionRequeue = settings.RegisterBoolSetting(
+	settings.SystemOnly,
+	"kv.priority_inversion_requeue_replicate_queue.enabled",
+	"whether the requeue replicas should requeue when enqueued for "+
+		"repair action but ended up consider rebalancing during processing",
+	false,
+)
+
 // ReplicateQueueMaxSize is a setting that controls the max size of the
 // replicate queue. When this limit is exceeded, lower priority replicas (not
 // guaranteed to be the lowest) are dropped from the queue.