Merge pull request #7057 from ethereum-optimism/aj/l2-transactions

op-program: Support prefetching l2-transactions

op-program/client/l2/oracle.go

@@ -64,9 +64,15 @@ func (p *PreimageOracle) headerByBlockHash(blockHash common.Hash) *types.Header
 
 func (p *PreimageOracle) BlockByHash(blockHash common.Hash) *types.Block {
 	header := p.headerByBlockHash(blockHash)
+	txs := p.LoadTransactions(blockHash, header.TxHash)
+
+	return types.NewBlockWithHeader(header).WithBody(txs, nil)
+}
+
+func (p *PreimageOracle) LoadTransactions(blockHash common.Hash, txHash common.Hash) []*types.Transaction {
 	p.hint.Hint(TransactionsHint(blockHash))
 
-	opaqueTxs := mpt.ReadTrie(header.TxHash, func(key common.Hash) []byte {
+	opaqueTxs := mpt.ReadTrie(txHash, func(key common.Hash) []byte {
 		return p.oracle.Get(preimage.Keccak256Key(key))
 	})
 
@@ -74,8 +80,7 @@ func (p *PreimageOracle) BlockByHash(blockHash common.Hash) *types.Block {
 	if err != nil {
 		panic(fmt.Errorf("failed to decode list of txs: %w", err))
 	}
-
-	return types.NewBlockWithHeader(header).WithBody(txs, nil)
+	return txs
 }
 
 func (p *PreimageOracle) NodeByHash(nodeHash common.Hash) []byte {

op-program/host/prefetcher/prefetcher.go

@@ -99,7 +99,7 @@ func (p *Prefetcher) prefetch(ctx context.Context, hint string) error {
 			return fmt.Errorf("failed to fetch L1 block %s receipts: %w", hash, err)
 		}
 		return p.storeReceipts(receipts)
-	case l2.HintL2BlockHeader:
+	case l2.HintL2BlockHeader, l2.HintL2Transactions:
 		header, txs, err := p.l2Fetcher.InfoAndTxsByHash(ctx, hash)
 		if err != nil {
 			return fmt.Errorf("failed to fetch L2 block %s: %w", hash, err)

op-program/host/prefetcher/prefetcher_test.go

@@ -180,6 +180,31 @@ func TestFetchL2Block(t *testing.T) {
 	})
 }
 
+func TestFetchL2Transactions(t *testing.T) {
+	rng := rand.New(rand.NewSource(123))
+	block, rcpts := testutils.RandomBlock(rng, 10)
+	hash := block.Hash()
+
+	t.Run("AlreadyKnown", func(t *testing.T) {
+		prefetcher, _, _, kv := createPrefetcher(t)
+		storeBlock(t, kv, block, rcpts)
+
+		oracle := l2.NewPreimageOracle(asOracleFn(t, prefetcher), asHinter(t, prefetcher))
+		result := oracle.LoadTransactions(hash, block.TxHash())
+		assertTransactionsEqual(t, block.Transactions(), result)
+	})
+
+	t.Run("Unknown", func(t *testing.T) {
+		prefetcher, _, l2Cl, _ := createPrefetcher(t)
+		l2Cl.ExpectInfoAndTxsByHash(hash, eth.BlockToInfo(block), block.Transactions(), nil)
+		defer l2Cl.MockL2Client.AssertExpectations(t)
+
+		oracle := l2.NewPreimageOracle(asOracleFn(t, prefetcher), asHinter(t, prefetcher))
+		result := oracle.LoadTransactions(hash, block.TxHash())
+		assertTransactionsEqual(t, block.Transactions(), result)
+	})
+}
+
 func TestFetchL2Node(t *testing.T) {
 	rng := rand.New(rand.NewSource(123))
 	node := testutils.RandomData(rng, 30)