Implement block_transaction_count_by_hash for EthApi (#34)

* Implement block_transaction_count_by_hash for EthApi

* Return Option for block_transaction_count_by_hash

* Fix 34#discussion_r438018163

* Remove sp-blockchain dependency

rpc/core/src/eth.rs

@@ -93,7 +93,7 @@ pub trait EthApi {
 
 	/// Returns the number of transactions in a block with given hash.
 	#[rpc(name = "eth_getBlockTransactionCountByHash")]
-	fn block_transaction_count_by_hash(&self, _: H256) -> BoxFuture<Option<U256>>;
+	fn block_transaction_count_by_hash(&self, _: H256) -> Result<Option<U256>>;
 
 	/// Returns the number of transactions in a block with given block number.
 	#[rpc(name = "eth_getBlockTransactionCountByNumber")]

rpc/primitives/src/lib.rs

@@ -45,6 +45,7 @@ sp_api::decl_runtime_apis! {
 		fn block_by_number(number: u32) -> Option<EthereumBlock>;
 		fn block_transaction_count_by_number(number: u32) -> Option<U256>;
 		fn block_by_hash(hash: H256) -> Option<EthereumBlock>;
+		fn block_transaction_count_by_hash(hash: H256) -> Option<U256>;
 	}
 }
 

rpc/src/lib.rs

@@ -27,7 +27,6 @@ use sp_transaction_pool::TransactionPool;
 use sc_client_api::backend::{StorageProvider, Backend, StateBackend};
 use sha3::{Keccak256, Digest};
 use sp_runtime::traits::BlakeTwo256;
-
 use frontier_rpc_core::EthApi as EthApiT;
 use frontier_rpc_core::types::{
 	BlockNumber, Bytes, CallRequest, EthAccount, Filter, Index, Log, Receipt, RichBlock,
@@ -246,8 +245,16 @@ impl<B, C, SC, P, CT, BE> EthApiT for EthApi<B, C, SC, P, CT, BE> where
 		   .map_err(|_| internal_err("fetch runtime account basic failed"))?.nonce.into())
 	}
 
-	fn block_transaction_count_by_hash(&self, _: H256) -> BoxFuture<Option<U256>> {
-		unimplemented!("block_transaction_count_by_hash");
+	fn block_transaction_count_by_hash(&self, hash: H256) -> Result<Option<U256>> {
+		let header = self.select_chain.best_chain()
+			.map_err(|_| internal_err("fetch header failed"))?;
+
+		let result = match self.client.runtime_api()
+			.block_transaction_count_by_hash(&BlockId::Hash(header.hash()), hash) {
+			Ok(result) => result,
+			Err(_) => return Ok(None)
+		};
+		Ok(result)
 	}
 
 	fn block_transaction_count_by_number(&self, number: BlockNumber) -> Result<Option<U256>> {

template/runtime/src/lib.rs

@@ -485,6 +485,13 @@ impl_runtime_apis! {
 			None
 		}
 
+		fn block_transaction_count_by_hash(hash: H256) -> Option<U256> {
+			if let Some(block) = <ethereum::Module<Runtime>>::block_by_hash(hash) {
+				return Some(U256::from(block.transactions.len()))
+			}
+			None
+		}
+
 		fn block_by_hash(hash: H256) -> Option<EthereumBlock> {
 			<ethereum::Module<Runtime>>::block_by_hash(hash)
 		}