kvnemesis: rename Restarter interface to ServerController

Previously, the interface for controlling test servers was named
`Restarter`, which only described one of its methods. This was
inadequate because the interface also provides `StopServer`, and
future changes will add more server control methods like
`CrashServer`.

This patch renames `Restarter` to `ServerController` to better
reflect its broader purpose of controlling server lifecycle
operations. All references to the interface and its field in
`Env` have been updated accordingly.

Release note: None
Informs: #64828

Author: dodeca12

pkg/kv/kvnemesis/applier.go

@@ -182,12 +182,12 @@ func (a *Applier) applyOp(ctx context.Context, db *kv.DB, op *Operation) {
 		o.Result = resultInit(ctx, err)
 	case *StopNodeOperation:
 		serverID := int(o.NodeId) - 1
-		a.env.Restarter.StopServer(serverID)
+		a.env.ServerController.StopServer(serverID)
 		a.nodes.setStopped(int(o.NodeId))
 		o.Result = resultInit(ctx, nil)
 	case *RestartNodeOperation:
 		serverID := int(o.NodeId) - 1
-		err := a.env.Restarter.RestartServer(serverID)
+		err := a.env.ServerController.RestartServer(serverID)
 		a.nodes.setRunning(int(o.NodeId))
 		o.Result = resultInit(ctx, err)
 	case *ClosureTxnOperation:

pkg/kv/kvnemesis/env.go

@@ -27,19 +27,19 @@ type Logger interface {
 	WriteFile(basename string, contents string) string
 }
 
-type Restarter interface {
+type ServerController interface {
 	StopServer(idx int)
 	RestartServer(idx int) error
 }
 
 // Env manipulates the environment (cluster settings, zone configurations) that
 // the Applier operates in.
 type Env struct {
-	SQLDBs      []*gosql.DB
-	Tracker     *SeqTracker
-	L           Logger
-	Partitioner *rpc.Partitioner
-	Restarter   Restarter
+	SQLDBs           []*gosql.DB
+	Tracker          *SeqTracker
+	L                Logger
+	Partitioner      *rpc.Partitioner
+	ServerController ServerController
 }
 
 func (e *Env) anyNode() *gosql.DB {

pkg/kv/kvnemesis/kvnemesis.go

@@ -197,7 +197,7 @@ func RunNemesis(
 	}
 	env.Partitioner.EnablePartitions(false)
 	for i := 0; i < config.NumNodes; i++ {
-		_ = env.Restarter.RestartServer(i)
+		_ = env.ServerController.RestartServer(i)
 	}
 
 	allSteps := make(steps, 0, numSteps)

pkg/kv/kvnemesis/kvnemesis_test.go

@@ -697,7 +697,7 @@ func testKVNemesisImpl(t testing.TB, cfg kvnemesisTestCfg) {
 
 	logger := newTBridge(t)
 	defer dumpRaftLogsOnFailure(t, logger.ll.dir, tc.Servers)
-	env := &Env{SQLDBs: sqlDBs, Tracker: tr, L: logger, Partitioner: &partitioner, Restarter: tc}
+	env := &Env{SQLDBs: sqlDBs, Tracker: tr, L: logger, Partitioner: &partitioner, ServerController: tc}
 	failures, err := RunNemesis(ctx, rng, env, config, cfg.concurrency, cfg.numSteps, cfg.mode, dbs...)
 
 	logMetricsReport(t, tc)