etcdserver: cap new keys on space alarm

integration/v3_grpc_test.go

@@ -542,6 +542,54 @@ func TestV3StorageQuotaApply(t *testing.T) {
 	if _, err := kvc0.Put(context.TODO(), &pb.PutRequest{Key: key, Value: smallbuf}); err == nil {
 		t.Fatalf("past-quota instance should reject put")
 	}
+
+	// large quota machine should reject put
+	if _, err := kvc1.Put(context.TODO(), &pb.PutRequest{Key: key, Value: smallbuf}); err == nil {
+		t.Fatalf("past-quota instance should reject put")
+	}
+
+	// reset large quota node to ensure alarm persisted
+	backend.InitialMmapSize = oldSize
+	clus.Members[1].Stop(t)
+	clus.Members[1].Restart(t)
+	clus.waitLeader(t, clus.Members)
+
+	if _, err := kvc1.Put(context.TODO(), &pb.PutRequest{Key: key, Value: smallbuf}); err == nil {
+		t.Fatalf("alarmed instance should reject put after reset")
+	}
+}
+
+// TestV3AlarmDeactivate ensures that space alarms can be deactivated so puts go through.
+func TestV3AlarmDeactivate(t *testing.T) {
+	clus := NewClusterV3(t, &ClusterConfig{Size: 3})
+	defer clus.Terminate(t)
+	kvc := toGRPC(clus.RandClient()).KV
+	mt := toGRPC(clus.RandClient()).Maintenance
+
+	alarmReq := &pb.AlarmRequest{
+		MemberID: 123,
+		Action:   pb.AlarmRequest_ACTIVATE,
+		Alarm:    pb.AlarmType_NOSPACE,
+	}
+	if _, err := mt.Alarm(context.TODO(), alarmReq); err != nil {
+		t.Fatal(err)
+	}
+
+	key := []byte("abc")
+	smallbuf := make([]byte, 512)
+	_, err := kvc.Put(context.TODO(), &pb.PutRequest{Key: key, Value: smallbuf})
+	if err == nil && err != rpctypes.ErrNoSpace {
+		t.Fatalf("put got %v, expected %v", err, rpctypes.ErrNoSpace)
+	}
+
+	alarmReq.Action = pb.AlarmRequest_DEACTIVATE
+	if _, err = mt.Alarm(context.TODO(), alarmReq); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err = kvc.Put(context.TODO(), &pb.PutRequest{Key: key, Value: smallbuf}); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestV3RangeRequest(t *testing.T) {