kvclient: remove unused MoveToFront

This commit removes ths MoveToFront method on the Transport. A major
advantage of this change is that the Transport no longer modifies the
underlying ReplicaSlice. This will allow a future commit to avoid
copying the slice to every transport.

Epic: none

Release note: None

pkg/kv/kvclient/kvcoord/dist_sender_rangefeed_test.go

@@ -157,10 +157,6 @@ func (c *countConnectionsTransport) SkipReplica() {
 	c.wrapped.SkipReplica()
 }
 
-func (c *countConnectionsTransport) MoveToFront(descriptor roachpb.ReplicaDescriptor) bool {
-	return c.wrapped.MoveToFront(descriptor)
-}
-
 func (c *countConnectionsTransport) Release() {
 	c.wrapped.Release()
 }

pkg/kv/kvclient/kvcoord/dist_sender_test.go

@@ -198,22 +198,6 @@ func (l *simpleTransportAdapter) SkipReplica() {
 	l.nextReplicaIdx++
 }
 
-func (l *simpleTransportAdapter) MoveToFront(replica roachpb.ReplicaDescriptor) bool {
-	for i := range l.replicas {
-		if l.replicas[i].IsSame(replica) {
-			// If we've already processed the replica, decrement the current
-			// index before we swap.
-			if i < l.nextReplicaIdx {
-				l.nextReplicaIdx--
-			}
-			// Swap the client representing this replica to the front.
-			l.replicas[i], l.replicas[l.nextReplicaIdx] = l.replicas[l.nextReplicaIdx], l.replicas[i]
-			return true
-		}
-	}
-	return false
-}
-
 func (l *simpleTransportAdapter) Release() {}
 
 func makeGossip(t *testing.T, stopper *stop.Stopper, rpcContext *rpc.Context) *gossip.Gossip {

pkg/kv/kvclient/kvcoord/send_test.go

@@ -189,10 +189,6 @@ func (f *firstNErrorTransport) SkipReplica() {
 	panic("SkipReplica not supported")
 }
 
-func (*firstNErrorTransport) MoveToFront(roachpb.ReplicaDescriptor) bool {
-	return true
-}
-
 // TestComplexScenarios verifies various complex success/failure scenarios by
 // mocking sendOne.
 func TestComplexScenarios(t *testing.T) {

pkg/kv/kvclient/kvcoord/transport.go

@@ -78,13 +78,6 @@ type Transport interface {
 	// - the replica that NextReplica() would return is skipped.
 	SkipReplica()
 
-	// MoveToFront locates the specified replica and moves it to the
-	// front of the ordering of replicas to try. If the replica has
-	// already been tried, it will be retried. Returns false if the specified
-	// replica can't be found and thus can't be moved to the front of the
-	// transport.
-	MoveToFront(roachpb.ReplicaDescriptor) bool
-
 	// Release releases any resources held by this Transport.
 	Release()
 }
@@ -267,22 +260,6 @@ func (gt *grpcTransport) SkipReplica() {
 	gt.nextReplicaIdx++
 }
 
-func (gt *grpcTransport) MoveToFront(replica roachpb.ReplicaDescriptor) bool {
-	for i := range gt.replicas {
-		if gt.replicas[i].IsSame(replica) {
-			// If we've already processed the replica, decrement the current
-			// index before we swap.
-			if i < gt.nextReplicaIdx {
-				gt.nextReplicaIdx--
-			}
-			// Swap the client representing this replica to the front.
-			gt.replicas[i], gt.replicas[gt.nextReplicaIdx] = gt.replicas[gt.nextReplicaIdx], gt.replicas[i]
-			return true
-		}
-	}
-	return false
-}
-
 // splitHealthy splits the grpcTransport's replica slice into healthy replica
 // and unhealthy replica, based on their connection state. Healthy replicas will
 // be rearranged first in the replicas slice, and unhealthy replicas will be
@@ -390,8 +367,4 @@ func (s *senderTransport) SkipReplica() {
 	s.called = true
 }
 
-func (s *senderTransport) MoveToFront(replica roachpb.ReplicaDescriptor) bool {
-	return true
-}
-
 func (s *senderTransport) Release() {}

pkg/kv/kvclient/kvcoord/transport_test.go

@@ -18,7 +18,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/testutils"
-	"github.com/cockroachdb/cockroach/pkg/util/caller"
 	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/tracing"
@@ -27,85 +26,6 @@ import (
 	"google.golang.org/grpc"
 )
 
-func TestTransportMoveToFront(t *testing.T) {
-	defer leaktest.AfterTest(t)()
-	defer log.Scope(t).Close(t)
-	rd1 := roachpb.ReplicaDescriptor{NodeID: 1, StoreID: 1, ReplicaID: 1}
-	rd2 := roachpb.ReplicaDescriptor{NodeID: 2, StoreID: 2, ReplicaID: 2}
-	rd3 := roachpb.ReplicaDescriptor{NodeID: 3, StoreID: 3, ReplicaID: 3}
-	rd3Incoming := roachpb.ReplicaDescriptor{NodeID: 3, StoreID: 3, ReplicaID: 3,
-		Type: roachpb.VOTER_INCOMING}
-	gt := grpcTransport{replicas: []roachpb.ReplicaDescriptor{rd1, rd2, rd3}}
-
-	verifyOrder := func(replicas []roachpb.ReplicaDescriptor) {
-		file, line, _ := caller.Lookup(1)
-		for i, r := range gt.replicas {
-			if r != replicas[i] {
-				t.Fatalf("%s:%d: expected order %+v; got mismatch at index %d: %+v",
-					file, line, replicas, i, r)
-			}
-		}
-	}
-
-	verifyOrder([]roachpb.ReplicaDescriptor{rd1, rd2, rd3})
-
-	// Move replica 2 to the front.
-	gt.MoveToFront(rd2)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd2, rd1, rd3})
-
-	// Now replica 3.
-	gt.MoveToFront(rd3)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd3, rd1, rd2})
-
-	// Advance the client index and move replica 3 back to front.
-	gt.nextReplicaIdx++
-	gt.MoveToFront(rd3)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd3, rd1, rd2})
-	if gt.nextReplicaIdx != 0 {
-		t.Fatalf("expected client index 0; got %d", gt.nextReplicaIdx)
-	}
-
-	// Advance the client index again and verify replica 3 can
-	// be moved to front for a second retry.
-	gt.nextReplicaIdx++
-	gt.MoveToFront(rd3)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd3, rd1, rd2})
-	if gt.nextReplicaIdx != 0 {
-		t.Fatalf("expected client index 0; got %d", gt.nextReplicaIdx)
-	}
-
-	// Move replica 2 to the front.
-	gt.MoveToFront(rd2)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd2, rd1, rd3})
-
-	// Advance client index and move rd1 front; should be no change.
-	gt.nextReplicaIdx++
-	gt.MoveToFront(rd1)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd2, rd1, rd3})
-
-	// Advance client index and and move rd1 to front. Should move
-	// client index back for a retry.
-	gt.nextReplicaIdx++
-	gt.MoveToFront(rd1)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd2, rd1, rd3})
-	if gt.nextReplicaIdx != 1 {
-		t.Fatalf("expected client index 1; got %d", gt.nextReplicaIdx)
-	}
-
-	// Advance client index once more; verify second retry.
-	gt.nextReplicaIdx++
-	gt.MoveToFront(rd2)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd1, rd2, rd3})
-	if gt.nextReplicaIdx != 1 {
-		t.Fatalf("expected client index 1; got %d", gt.nextReplicaIdx)
-	}
-
-	// Move rd3 to front, even if the replica type differs.
-	gt.MoveToFront(rd3Incoming)
-	verifyOrder([]roachpb.ReplicaDescriptor{rd1, rd3, rd2})
-	require.Equal(t, 1, gt.nextReplicaIdx)
-}
-
 // TestSpanImport tests that the gRPC transport ingests trace information that
 // came from gRPC responses (via tracingpb.RecordedSpan on the batch responses).
 func TestSpanImport(t *testing.T) {