Fix state gen migration (#5858)

* Remove useless `currentSplitSlot == 0`
* Increase slots per archived point to 2048
* Don't delete last archived state
* Revert back to 256
* Merge branch 'master' of github.com:prysmaticlabs/prysm into fix-migration-delete-latest-state
* Don't delete last archived state
* Regression test
* Revert

beacon-chain/state/stategen/migrate.go

@@ -20,7 +20,7 @@ func (s *State) MigrateToCold(ctx context.Context, finalizedSlot uint64, finaliz
 	// Verify migration is sensible. The new finalized point must increase the current split slot, and
 	// on an epoch boundary for hot state summary scheme to work.
 	currentSplitSlot := s.splitInfo.slot
-	if currentSplitSlot == 0 || currentSplitSlot > finalizedSlot {
+	if currentSplitSlot > finalizedSlot {
 		return nil
 	}
 
@@ -74,7 +74,8 @@ func (s *State) MigrateToCold(ctx context.Context, finalizedSlot uint64, finaliz
 			// Do not delete the current finalized state in case user wants to
 			// switch back to old state service, deleting the recent finalized state
 			// could cause issue switching back.
-			if s.beaconDB.HasState(ctx, r) && r != finalizedRoot {
+			lastArchivedIndexRoot := s.beaconDB.LastArchivedIndexRoot(ctx)
+			if s.beaconDB.HasState(ctx, r) && r != lastArchivedIndexRoot && r != finalizedRoot {
 				if err := s.beaconDB.DeleteState(ctx, r); err != nil {
 					// For whatever reason if node is unable to delete a state due to
 					// state is finalized, it is more reasonable to continue than to exit.

beacon-chain/state/stategen/migrate_test.go

@@ -105,3 +105,71 @@ func TestMigrateToCold_MigrationCompletes(t *testing.T) {
 	testutil.AssertLogsContain(t, hook, "Deleted state during migration")
 	testutil.AssertLogsContain(t, hook, "Set hot and cold state split point")
 }
+
+func TestMigrateToCold_CantDeleteCurrentArchivedIndex(t *testing.T) {
+	ctx := context.Background()
+	db := testDB.SetupDB(t)
+
+	service := New(db, cache.NewStateSummaryCache())
+	service.splitInfo.slot = 1
+	service.slotsPerArchivedPoint = 2
+
+	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
+	if err := beaconState.SetSlot(params.BeaconConfig().SlotsPerEpoch); err != nil {
+		t.Fatal(err)
+	}
+	b := &ethpb.SignedBeaconBlock{
+		Block: &ethpb.BeaconBlock{Slot: 2},
+	}
+	if err := service.beaconDB.SaveBlock(ctx, b); err != nil {
+		t.Fatal(err)
+	}
+	bRoot, err := stateutil.BlockRoot(b.Block)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bRoot[:], Slot: 2}); err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveState(ctx, beaconState, bRoot); err != nil {
+		t.Fatal(err)
+	}
+
+	newBeaconState, _ := testutil.DeterministicGenesisState(t, 32)
+	if err := newBeaconState.SetSlot(3); err != nil {
+		t.Fatal(err)
+	}
+	b = &ethpb.SignedBeaconBlock{
+		Block: &ethpb.BeaconBlock{Slot: 3},
+	}
+	if err := service.beaconDB.SaveBlock(ctx, b); err != nil {
+		t.Fatal(err)
+	}
+	bRoot, err = stateutil.BlockRoot(b.Block)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bRoot[:], Slot: 3}); err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveState(ctx, newBeaconState, bRoot); err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveArchivedPointRoot(ctx, bRoot, 1); err != nil {
+		t.Fatal(err)
+	}
+	if err := service.beaconDB.SaveLastArchivedIndex(ctx, 1); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := service.MigrateToCold(ctx, beaconState.Slot(), [32]byte{}); err != nil {
+		t.Fatal(err)
+	}
+
+	if !service.beaconDB.HasArchivedPoint(ctx, 1) {
+		t.Error("Did not preserve archived point")
+	}
+	if !service.beaconDB.HasState(ctx, bRoot) {
+		t.Error("State should not be deleted")
+	}
+}