op-program: Avoid requesting L1 genesis block when starting from L2 g…

…enesis (ethereum-optimism#9807)

* op-program: Avoid requesting L1 genesis block when starting from L2 genesis.

* op-program: Fix unit tests

op-node/node/safedb/disabled.go

@@ -14,6 +14,10 @@ var (
 	ErrNotEnabled = errors.New("safe head database not enabled")
 )
 
+func (d *DisabledDB) Enabled() bool {
+	return false
+}
+
 func (d *DisabledDB) SafeHeadUpdated(_ eth.L2BlockRef, _ eth.BlockID) error {
 	return nil
 }

op-node/node/safedb/safedb.go

@@ -93,6 +93,10 @@ func NewSafeDB(logger log.Logger, path string) (*SafeDB, error) {
 	}, nil
 }
 
+func (d *SafeDB) Enabled() bool {
+	return true
+}
+
 func (d *SafeDB) SafeHeadUpdated(safeHead eth.L2BlockRef, l1Head eth.BlockID) error {
 	d.m.Lock()
 	defer d.m.Unlock()

op-node/rollup/derive/engine_queue.go

@@ -99,6 +99,12 @@ type LocalEngineControl interface {
 // The safe head may advance by more than one block in a single update
 // The l1Block specified is the first L1 block that includes sufficient information to derive the new safe head
 type SafeHeadListener interface {
+
+	// Enabled reports if this safe head listener is actively using the posted data. This allows the engine queue to
+	// optionally skip making calls that may be expensive to prepare.
+	// Callbacks may still be made if Enabled returns false but are not guaranteed.
+	Enabled() bool
+
 	// SafeHeadUpdated indicates that the safe head has been updated in response to processing batch data
 	// The l1Block specified is the first L1 block containing all required batch data to derive newSafeHead
 	SafeHeadUpdated(newSafeHead eth.L2BlockRef, l1Block eth.BlockID) error
@@ -723,7 +729,7 @@ func (eq *EngineQueue) Reset(ctx context.Context, _ eth.L1BlockRef, _ eth.System
 	if err := eq.safeHeadNotifs.SafeHeadReset(safe); err != nil {
 		return err
 	}
-	if safe.Number == eq.cfg.Genesis.L2.Number && safe.Hash == eq.cfg.Genesis.L2.Hash {
+	if eq.safeHeadNotifs.Enabled() && safe.Number == eq.cfg.Genesis.L2.Number && safe.Hash == eq.cfg.Genesis.L2.Hash {
 		// The rollup genesis block is always safe by definition. So if the pipeline resets this far back we know
 		// we will process all safe head updates and can record genesis as always safe from L1 genesis.
 		// Note that it is not safe to use cfg.Genesis.L1 here as it is the block immediately before the L2 genesis

op-node/rollup/derive/engine_queue_test.go

@@ -898,7 +898,6 @@ func TestBlockBuildingRace(t *testing.T) {
 	l1F.ExpectL1BlockRefByNumber(refA.Number, refA, nil)
 	l1F.ExpectL1BlockRefByHash(refA.Hash, refA, nil)
 	l1F.ExpectL1BlockRefByHash(refA.Hash, refA, nil)
-	l1F.ExpectL1BlockRefByNumber(0, refA, nil)
 
 	eng.ExpectSystemConfigByL2Hash(refA0.Hash, cfg.Genesis.SystemConfig, nil)
 
@@ -1024,7 +1023,6 @@ func TestResetLoop(t *testing.T) {
 
 	rng := rand.New(rand.NewSource(1234))
 
-	l1Genesis := eth.L1BlockRef{Number: 0}
 	refA := testutils.RandomBlockRef(rng)
 	refA0 := eth.L2BlockRef{
 		Hash:           testutils.RandomHash(rng),
@@ -1082,7 +1080,6 @@ func TestResetLoop(t *testing.T) {
 	eng.ExpectL2BlockRefByHash(refA1.Hash, refA1, nil)
 	eng.ExpectL2BlockRefByHash(refA0.Hash, refA0, nil)
 	eng.ExpectSystemConfigByL2Hash(refA0.Hash, cfg.Genesis.SystemConfig, nil)
-	l1F.ExpectL1BlockRefByNumber(0, l1Genesis, nil)
 	l1F.ExpectL1BlockRefByNumber(refA.Number, refA, nil)
 	l1F.ExpectL1BlockRefByHash(refA.Hash, refA, nil)
 	l1F.ExpectL1BlockRefByHash(refA.Hash, refA, nil)