decode block rlp less often (#9252)

in total:
- removed 4 redundant rlp deserializations
- avoid 1 redundant block data copy

parity/blockchain.rs

@@ -30,6 +30,7 @@ use ethcore::client::{Mode, DatabaseCompactionProfile, VMType, BlockImportError,
 use ethcore::error::{ImportErrorKind, BlockImportErrorKind};
 use ethcore::miner::Miner;
 use ethcore::verification::queue::VerifierSettings;
+use ethcore::verification::queue::kind::blocks::Unverified;
 use ethcore_service::ClientService;
 use cache::CacheConfig;
 use informant::{Informant, FullNodeInformantData, MillisecondDuration};
@@ -417,8 +418,9 @@ fn execute_import(cmd: ImportBlockchain) -> Result<(), String> {
 	service.register_io_handler(informant).map_err(|_| "Unable to register informant handler".to_owned())?;
 
 	let do_import = |bytes| {
+		let block = Unverified::from_rlp(bytes).map_err(|_| "Invalid block rlp")?;
 		while client.queue_info().is_full() { sleep(Duration::from_secs(1)); }
-		match client.import_block(bytes) {
+		match client.import_block(block) {
 			Err(BlockImportError(BlockImportErrorKind::Import(ImportErrorKind::AlreadyInChain), _)) => {
 				trace!("Skipping block already in chain.");
 			}