Merge pull request #111 from ethereum-optimism/contract-code-method

core: reinstate ContractCode function to support snap-sync from legacy DB nodes

cmd/devp2p/internal/ethtest/snap.go

@@ -249,11 +249,11 @@ func (s *Suite) TestSnapGetByteCodes(t *utesting.T) {
 		// A few stateroots
 		{
 			nBytes: 10000, hashes: []common.Hash{s.chain.RootAt(0), s.chain.RootAt(999)},
-			expHashes: 0,
+			expHashes: 1, // 32-byte keys are detected as code, even if not code (like genesis hash), in legacy lookups.
 		},
 		{
 			nBytes: 10000, hashes: []common.Hash{s.chain.RootAt(0), s.chain.RootAt(0)},
-			expHashes: 0,
+			expHashes: 2, // 32-byte keys are detected as code, even if not code (like genesis hash), in legacy lookups.
 		},
 		// Empties
 		{

core/blockchain_reader.go

@@ -311,6 +311,14 @@ func (bc *BlockChain) ContractCodeWithPrefix(hash common.Hash) ([]byte, error) {
 	return bc.stateCache.(codeReader).ContractCodeWithPrefix(common.Hash{}, hash)
 }
 
+// ContractCode retrieves a blob of data associated with a contract hash
+// either from ephemeral in-memory cache, or from persistent storage.
+// This is a legacy-method, replaced by ContractCodeWithPrefix,
+// but required for old databases to serve snap-sync.
+func (bc *BlockChain) ContractCode(hash common.Hash) ([]byte, error) {
+	return bc.stateCache.ContractCode(common.Hash{}, hash)
+}
+
 // State returns a new mutable state based on the current HEAD block.
 func (bc *BlockChain) State() (*state.StateDB, error) {
 	return bc.StateAt(bc.CurrentBlock().Root)