op-program: Modify L2 oracle to not return error

op-program/client/l2/db.go

@@ -40,12 +40,12 @@ func (o *OracleKeyValueStore) Get(key []byte) ([]byte, error) {
 
 	if len(key) == codePrefixedKeyLength && bytes.HasPrefix(key, rawdb.CodePrefix) {
 		key = key[len(rawdb.CodePrefix):]
-		return o.oracle.CodeByHash(*(*[common.HashLength]byte)(key))
+		return o.oracle.CodeByHash(*(*[common.HashLength]byte)(key)), nil
 	}
 	if len(key) != common.HashLength {
 		return nil, ErrInvalidKeyLength
 	}
-	return o.oracle.NodeByHash(*(*[common.HashLength]byte)(key))
+	return o.oracle.NodeByHash(*(*[common.HashLength]byte)(key)), nil
 }
 
 func (o *OracleKeyValueStore) NewBatch() ethdb.Batch {

op-program/client/l2/db_test.go

 package l2
 
 import (
-	"fmt"
 	"math/big"
 	"testing"
 
@@ -27,16 +26,8 @@ var (
 var _ ethdb.KeyValueStore = (*OracleKeyValueStore)(nil)
 
 func TestGet(t *testing.T) {
-	t.Run("UnknownKey", func(t *testing.T) {
-		oracle := newStubStateOracle()
-		db := NewOracleBackedDB(oracle)
-		val, err := db.Get(common.Hash{}.Bytes())
-		require.Error(t, err)
-		require.Nil(t, val)
-	})
-
 	t.Run("IncorrectLengthKey", func(t *testing.T) {
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		db := NewOracleBackedDB(oracle)
 		val, err := db.Get([]byte{1, 2, 3})
 		require.ErrorIs(t, err, ErrInvalidKeyLength)
@@ -44,7 +35,7 @@ func TestGet(t *testing.T) {
 	})
 
 	t.Run("KeyWithCodePrefix", func(t *testing.T) {
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		db := NewOracleBackedDB(oracle)
 		key := common.HexToHash("0x12345678")
 		prefixedKey := append(rawdb.CodePrefix, key.Bytes()...)
@@ -58,7 +49,7 @@ func TestGet(t *testing.T) {
 	})
 
 	t.Run("NormalKeyThatHappensToStartWithCodePrefix", func(t *testing.T) {
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		db := NewOracleBackedDB(oracle)
 		key := make([]byte, common.HashLength)
 		copy(rawdb.CodePrefix, key)
@@ -74,7 +65,7 @@ func TestGet(t *testing.T) {
 	t.Run("KnownKey", func(t *testing.T) {
 		key := common.HexToHash("0xAA4488")
 		expected := []byte{2, 6, 3, 8}
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		oracle.data[key] = expected
 		db := NewOracleBackedDB(oracle)
 		val, err := db.Get(key.Bytes())
@@ -85,7 +76,7 @@ func TestGet(t *testing.T) {
 
 func TestPut(t *testing.T) {
 	t.Run("NewKey", func(t *testing.T) {
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		db := NewOracleBackedDB(oracle)
 		key := common.HexToHash("0xAA4488")
 		value := []byte{2, 6, 3, 8}
@@ -97,7 +88,7 @@ func TestPut(t *testing.T) {
 		require.Equal(t, value, actual)
 	})
 	t.Run("ReplaceKey", func(t *testing.T) {
-		oracle := newStubStateOracle()
+		oracle := newStubStateOracle(t)
 		db := NewOracleBackedDB(oracle)
 		key := common.HexToHash("0xAA4488")
 		value1 := []byte{2, 6, 3, 8}
@@ -119,6 +110,7 @@ func TestSupportsStateDBOperations(t *testing.T) {
 	genesisBlock := l2Genesis.MustCommit(realDb)
 
 	loader := &kvStateOracle{
+		t:      t,
 		source: realDb,
 	}
 	assertStateDataAvailable(t, NewOracleBackedDB(loader), l2Genesis, genesisBlock)
@@ -126,7 +118,7 @@ func TestSupportsStateDBOperations(t *testing.T) {
 
 func TestUpdateState(t *testing.T) {
 	l2Genesis := createGenesis()
-	oracle := newStubStateOracle()
+	oracle := newStubStateOracle(t)
 	db := rawdb.NewDatabase(NewOracleBackedDB(oracle))
 
 	genesisBlock := l2Genesis.MustCommit(db)
@@ -203,43 +195,50 @@ func assertStateDataAvailable(t *testing.T, db ethdb.KeyValueStore, l2Genesis *c
 	require.Equal(t, common.Hash{}, statedb.GetCodeHash(unknownAccount), "unset account code hash")
 }
 
-func newStubStateOracle() *stubStateOracle {
+func newStubStateOracle(t *testing.T) *stubStateOracle {
 	return &stubStateOracle{
+		t:    t,
 		data: make(map[common.Hash][]byte),
 		code: make(map[common.Hash][]byte),
 	}
 }
 
 type stubStateOracle struct {
+	t    *testing.T
 	data map[common.Hash][]byte
 	code map[common.Hash][]byte
 }
 
-func (o *stubStateOracle) NodeByHash(nodeHash common.Hash) ([]byte, error) {
+func (o *stubStateOracle) NodeByHash(nodeHash common.Hash) []byte {
 	data, ok := o.data[nodeHash]
 	if !ok {
-		return nil, fmt.Errorf("no value for node %v", nodeHash)
+		o.t.Fatalf("no value for node %v", nodeHash)
 	}
-	return data, nil
+	return data
 }
 
-func (o *stubStateOracle) CodeByHash(hash common.Hash) ([]byte, error) {
+func (o *stubStateOracle) CodeByHash(hash common.Hash) []byte {
 	data, ok := o.code[hash]
 	if !ok {
-		return nil, fmt.Errorf("no value for code %v", hash)
+		o.t.Fatalf("no value for code %v", hash)
 	}
-	return data, nil
+	return data
 }
 
 // kvStateOracle loads data from a source ethdb.KeyValueStore
 type kvStateOracle struct {
+	t      *testing.T
 	source ethdb.KeyValueStore
 }
 
-func (o *kvStateOracle) NodeByHash(nodeHash common.Hash) ([]byte, error) {
-	return o.source.Get(nodeHash.Bytes())
+func (o *kvStateOracle) NodeByHash(nodeHash common.Hash) []byte {
+	val, err := o.source.Get(nodeHash.Bytes())
+	if err != nil {
+		o.t.Fatalf("error retrieving node %v: %v", nodeHash, err)
+	}
+	return val
 }
 
-func (o *kvStateOracle) CodeByHash(hash common.Hash) ([]byte, error) {
-	return rawdb.ReadCode(o.source, hash), nil
+func (o *kvStateOracle) CodeByHash(hash common.Hash) []byte {
+	return rawdb.ReadCode(o.source, hash)
 }

op-program/client/l2/engine_backend.go

@@ -35,10 +35,7 @@ type OracleBackedL2Chain struct {
 var _ engineapi.EngineBackend = (*OracleBackedL2Chain)(nil)
 
 func NewOracleBackedL2Chain(logger log.Logger, oracle Oracle, chainCfg *params.ChainConfig, l2Head common.Hash) (*OracleBackedL2Chain, error) {
-	head, err := oracle.BlockByHash(l2Head)
-	if err != nil {
-		return nil, fmt.Errorf("loading l2 head: %w", err)
-	}
+	head := oracle.BlockByHash(l2Head)
 	logger.Info("Loaded L2 head", "hash", head.Hash(), "number", head.Number())
 	return &OracleBackedL2Chain{
 		log:      logger,
@@ -99,10 +96,7 @@ func (o *OracleBackedL2Chain) GetBlockByHash(hash common.Hash) *types.Block {
 		return block
 	}
 	// Retrieve from the oracle
-	block, err := o.oracle.BlockByHash(hash)
-	if err != nil {
-		handleError(err)
-	}
+	block = o.oracle.BlockByHash(hash)
 	if block == nil {
 		return nil
 	}
@@ -195,7 +189,3 @@ func (o *OracleBackedL2Chain) SetFinalized(header *types.Header) {
 func (o *OracleBackedL2Chain) SetSafe(header *types.Header) {
 	o.safe = header
 }
-
-func handleError(err error) {
-	panic(err)
-}

op-program/client/l2/engine_backend_test.go

@@ -113,8 +113,9 @@ func TestUpdateStateDatabaseWhenImportingBlock(t *testing.T) {
 
 	require.NotEqual(t, blocks[1].Root(), newBlock.Root(), "block should have modified world state")
 
-	_, err = chain.StateAt(newBlock.Root())
-	require.Error(t, err, "state from non-imported block should not be available")
+	require.Panics(t, func() {
+		_, _ = chain.StateAt(newBlock.Root())
+	}, "state from non-imported block should not be available")
 
 	err = chain.InsertBlockWithoutSetHead(newBlock)
 	require.NoError(t, err)
@@ -223,8 +224,8 @@ func newStubBlockOracle(chain []*types.Block, db ethdb.Database) *stubBlockOracl
 	}
 }
 
-func (o stubBlockOracle) BlockByHash(blockHash common.Hash) (*types.Block, error) {
-	return o.blocks[blockHash], nil
+func (o stubBlockOracle) BlockByHash(blockHash common.Hash) *types.Block {
+	return o.blocks[blockHash]
 }
 
 func TestEngineAPITests(t *testing.T) {

op-program/client/l2/oracle.go

@@ -11,13 +11,11 @@ type StateOracle interface {
 	// NodeByHash retrieves the merkle-patricia trie node pre-image for a given hash.
 	// Trie nodes may be from the world state trie or any account storage trie.
 	// Contract code is not stored as part of the trie and must be retrieved via CodeByHash
-	// Returns an error if the pre-image is unavailable.
-	NodeByHash(nodeHash common.Hash) ([]byte, error)
+	NodeByHash(nodeHash common.Hash) []byte
 
 	// CodeByHash retrieves the contract code pre-image for a given hash.
 	// codeHash should be retrieved from the world state account for a contract.
-	// Returns an error if the pre-image is unavailable.
-	CodeByHash(codeHash common.Hash) ([]byte, error)
+	CodeByHash(codeHash common.Hash) []byte
 }
 
 // Oracle defines the high-level API used to retrieve L2 data.
@@ -26,6 +24,5 @@ type Oracle interface {
 	StateOracle
 
 	// BlockByHash retrieves the block with the given hash.
-	// Returns an error if the block is not available.
-	BlockByHash(blockHash common.Hash) (*types.Block, error)
+	BlockByHash(blockHash common.Hash) *types.Block
 }

op-program/host/l2/fetcher.go

@@ -42,19 +42,26 @@ func NewFetchingL2Oracle(ctx context.Context, logger log.Logger, l2Url string) (
 	}, nil
 }
 
-func (o *FetchingL2Oracle) NodeByHash(hash common.Hash) ([]byte, error) {
+func (o *FetchingL2Oracle) NodeByHash(hash common.Hash) []byte {
 	// MPT nodes are stored as the hash of the node (with no prefix)
-	return o.dbGet(hash.Bytes())
+	node, err := o.dbGet(hash.Bytes())
+	if err != nil {
+		panic(err)
+	}
+	return node
 }
 
-func (o *FetchingL2Oracle) CodeByHash(hash common.Hash) ([]byte, error) {
+func (o *FetchingL2Oracle) CodeByHash(hash common.Hash) []byte {
 	// First try retrieving with the new code prefix
 	code, err := o.dbGet(append(rawdb.CodePrefix, hash.Bytes()...))
 	if err != nil {
 		// Fallback to the legacy un-prefixed version
-		return o.dbGet(hash.Bytes())
+		code, err = o.dbGet(hash.Bytes())
+		if err != nil {
+			panic(err)
+		}
 	}
-	return code, nil
+	return code
 }
 
 func (o *FetchingL2Oracle) dbGet(key []byte) ([]byte, error) {
@@ -66,10 +73,10 @@ func (o *FetchingL2Oracle) dbGet(key []byte) ([]byte, error) {
 	return node, nil
 }
 
-func (o *FetchingL2Oracle) BlockByHash(blockHash common.Hash) (*types.Block, error) {
+func (o *FetchingL2Oracle) BlockByHash(blockHash common.Hash) *types.Block {
 	block, err := o.blockSource.BlockByHash(o.ctx, blockHash)
 	if err != nil {
-		return nil, fmt.Errorf("fetch block %s: %w", blockHash.Hex(), err)
+		panic(fmt.Errorf("fetch block %s: %w", blockHash.Hex(), err))
 	}
-	return block, nil
+	return block
 }

op-program/host/l2/fetcher_test.go

@@ -63,9 +63,9 @@ func TestNodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		node, err := fetcher.NodeByHash(hash)
-		require.ErrorIs(t, err, stub.nextErr)
-		require.Nil(t, node)
+		require.Panics(t, func() {
+			fetcher.NodeByHash(hash)
+		})
 	})
 
 	t.Run("Success", func(t *testing.T) {
@@ -75,8 +75,7 @@ func TestNodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		node, err := fetcher.NodeByHash(hash)
-		require.NoError(t, err)
+		node := fetcher.NodeByHash(hash)
 		require.EqualValues(t, expected, node)
 	})
 
@@ -86,7 +85,7 @@ func TestNodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		_, _ = fetcher.NodeByHash(hash)
+		fetcher.NodeByHash(hash)
 		require.Len(t, stub.requests, 1, "should make single request")
 		req := stub.requests[0]
 		require.Equal(t, "debug_dbGet", req.method)
@@ -104,9 +103,7 @@ func TestCodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		node, err := fetcher.CodeByHash(hash)
-		require.ErrorIs(t, err, stub.nextErr)
-		require.Nil(t, node)
+		require.Panics(t, func() { fetcher.CodeByHash(hash) })
 	})
 
 	t.Run("Success", func(t *testing.T) {
@@ -116,8 +113,7 @@ func TestCodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		node, err := fetcher.CodeByHash(hash)
-		require.NoError(t, err)
+		node := fetcher.CodeByHash(hash)
 		require.EqualValues(t, expected, node)
 	})
 
@@ -127,7 +123,7 @@ func TestCodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		_, _ = fetcher.CodeByHash(hash)
+		fetcher.CodeByHash(hash)
 		require.Len(t, stub.requests, 1, "should make single request")
 		req := stub.requests[0]
 		require.Equal(t, "debug_dbGet", req.method)
@@ -141,7 +137,8 @@ func TestCodeByHash(t *testing.T) {
 		}
 		fetcher := newFetcher(nil, stub)
 
-		_, _ = fetcher.CodeByHash(hash)
+		// Panics because the code can't be found with or without the prefix
+		require.Panics(t, func() { fetcher.CodeByHash(hash) })
 		require.Len(t, stub.requests, 2, "should request with and without prefix")
 		req := stub.requests[0]
 		require.Equal(t, "debug_dbGet", req.method)
@@ -183,8 +180,7 @@ func TestBlockByHash(t *testing.T) {
 		stub := &stubBlockSource{nextResult: block}
 		fetcher := newFetcher(stub, nil)
 
-		res, err := fetcher.BlockByHash(hash)
-		require.NoError(t, err)
+		res := fetcher.BlockByHash(hash)
 		require.Same(t, block, res)
 	})
 
@@ -192,16 +188,16 @@ func TestBlockByHash(t *testing.T) {
 		stub := &stubBlockSource{nextErr: errors.New("boom")}
 		fetcher := newFetcher(stub, nil)
 
-		res, err := fetcher.BlockByHash(hash)
-		require.ErrorIs(t, err, stub.nextErr)
-		require.Nil(t, res)
+		require.Panics(t, func() {
+			fetcher.BlockByHash(hash)
+		})
 	})
 
 	t.Run("RequestArgs", func(t *testing.T) {
 		stub := &stubBlockSource{}
 		fetcher := newFetcher(stub, nil)
 
-		_, _ = fetcher.BlockByHash(hash)
+		fetcher.BlockByHash(hash)
 
 		require.Len(t, stub.requests, 1, "should make single request")
 		req := stub.requests[0]