Refactor return type of BlockChainClient::code #7098 (#11102)

* fix: refactor return type of `BlockChainClient::code`

* Add TODO move to `common-types`

Co-Authored-By: David <dvdplm@gmail.com>

ethcore/client-traits/src/lib.rs

@@ -67,6 +67,16 @@ pub enum StateOrBlock {
 	Block(BlockId)
 }
 
+/// Result to be used during get address code at given block's state
+// todo[botika] move to `common-types`
+pub enum StateResult<T> {
+	/// State is missing
+	Missing,
+
+	/// State is some
+	Some(T),
+}
+
 impl From<Box<dyn StateInfo>> for StateOrBlock {
 	fn from(info: Box<dyn StateInfo>) -> StateOrBlock {
 		StateOrBlock::State(info)
@@ -231,12 +241,14 @@ pub trait BlockChainClient : Sync + Send + AccountData + BlockChain + CallContra
 	fn block_hash(&self, id: BlockId) -> Option<H256>;
 
 	/// Get address code at given block's state.
-	fn code(&self, address: &Address, state: StateOrBlock) -> Option<Option<Bytes>>;
+	fn code(&self, address: &Address, state: StateOrBlock) -> StateResult<Option<Bytes>>;
 
 	/// Get address code at the latest block's state.
 	fn latest_code(&self, address: &Address) -> Option<Bytes> {
-		self.code(address, BlockId::Latest.into())
+		match self.code(address, BlockId::Latest.into()) {
-			.expect("code will return Some if given BlockId::Latest; qed")
+			StateResult::Missing => panic!("code will return Some if given BlockId::Latest; qed"),
+			StateResult::Some(t) => t,
+		}
 	}
 
 	/// Get a reference to the `BlockProvider`.

ethcore/src/client/client.rs

@@ -77,6 +77,7 @@ use client_traits::{
 	ScheduleInfo,
 	StateClient,
 	StateOrBlock,
+	StateResult,
 	Tick,
 	TransactionInfo
 };
@@ -1758,14 +1759,14 @@ impl BlockChainClient for Client {
 		Self::block_hash(&chain, id)
 	}
 
-	fn code(&self, address: &Address, state: StateOrBlock) -> Option<Option<Bytes>> {
+	fn code(&self, address: &Address, state: StateOrBlock) -> StateResult<Option<Bytes>> {
 		let result = match state {
 			StateOrBlock::State(s) => s.code(address).ok(),
 			StateOrBlock::Block(id) => self.state_at(id).and_then(|s| s.code(address).ok())
 		};
 
-		// Converting from `Option<Option<Arc<Bytes>>>` to `Option<Option<Bytes>>`
+		// Converting from `Option<Option<Arc<Bytes>>>` to `StateResult<Option<Bytes>>`
-		result.map(|c| c.map(|c| (&*c).clone()))
+		result.map_or(StateResult::Missing, |c| StateResult::Some(c.map(|c| (&*c).clone())))
 	}
 
 	fn storage_at(&self, address: &Address, position: &H256, state: StateOrBlock) -> Option<H256> {

ethcore/src/test_helpers/test_client.rs

@@ -71,7 +71,7 @@ use client::{
 use client_traits::{
 	BlockInfo, Nonce, Balance, ChainInfo, TransactionInfo, BlockChainClient, ImportBlock,
 	AccountData, BlockChain, IoClient, BadBlocks, ScheduleInfo, StateClient, ProvingBlockChainClient,
-	StateOrBlock
+	StateOrBlock, StateResult
 };
 use engine::Engine;
 use machine::executed::Executed;
@@ -702,10 +702,10 @@ impl BlockChainClient for TestBlockChainClient {
 		None
 	}
 
-	fn code(&self, address: &Address, state: StateOrBlock) -> Option<Option<Bytes>> {
+	fn code(&self, address: &Address, state: StateOrBlock) -> StateResult<Option<Bytes>> {
 		match state {
-			StateOrBlock::Block(BlockId::Latest) => Some(self.code.read().get(address).cloned()),
+			StateOrBlock::Block(BlockId::Latest) => StateResult::Some(self.code.read().get(address).cloned()),
-			_ => None,
+			_ => StateResult::Missing,
 		}
 	}
 

parity/blockchain.rs

@@ -26,7 +26,7 @@ use hash::{keccak, KECCAK_NULL_RLP};
 use ethereum_types::{U256, H256, Address};
 use bytes::ToPretty;
 use rlp::PayloadInfo;
-use client_traits::{BlockChainReset, Nonce, Balance, BlockChainClient, ImportExportBlocks};
+use client_traits::{BlockChainReset, Nonce, Balance, BlockChainClient, ImportExportBlocks, StateResult};
 use ethcore::{
 	client::{DatabaseCompactionProfile, VMType},
 	miner::Miner,
@@ -592,7 +592,10 @@ fn execute_export_state(cmd: ExportState) -> Result<(), String> {
 				out.write(b",").expect("Write error");
 			}
 			out.write_fmt(format_args!("\n\"0x{:x}\": {{\"balance\": \"{:x}\", \"nonce\": \"{:x}\"", account, balance, client.nonce(&account, at).unwrap_or_else(U256::zero))).expect("Write error");
-			let code = client.code(&account, at.into()).unwrap_or(None).unwrap_or_else(Vec::new);
+			let code = match client.code(&account, at.into()) {
+				StateResult::Missing => Vec::new(),
+				StateResult::Some(t) => t.unwrap_or_else(Vec::new),
+			};
 			if !code.is_empty() {
 				out.write_fmt(format_args!(", \"code_hash\": \"0x{:x}\"", keccak(&code))).expect("Write error");
 				if cmd.code {

rpc/src/v1/impls/eth.rs

@@ -25,7 +25,7 @@ use ethereum_types::{Address, H64, H160, H256, U64, U256, BigEndianHash};
 use parking_lot::Mutex;
 
 use account_state::state::StateInfo;
-use client_traits::{BlockChainClient, StateClient, ProvingBlockChainClient, StateOrBlock};
+use client_traits::{BlockChainClient, StateClient, ProvingBlockChainClient, StateOrBlock, StateResult};
 use ethash::{self, SeedHashCompute};
 use ethcore::client::{Call, EngineInfo};
 use ethcore::miner::{self, MinerService};
@@ -742,8 +742,8 @@ impl<C, SN: ?Sized, S: ?Sized, M, EM, T: StateInfo + 'static> Eth for EthClient<
 		try_bf!(check_known(&*self.client, num.clone()));
 
 		let res = match self.client.code(&address, self.get_state(num)) {
-			Some(code) => Ok(code.map_or_else(Bytes::default, Bytes::new)),
+			StateResult::Some(code) => Ok(code.map_or_else(Bytes::default, Bytes::new)),
-			None => Err(errors::state_pruned()),
+			StateResult::Missing => Err(errors::state_pruned()),
 		};
 
 		Box::new(future::done(res))