From 37c91a62ade1934c8a7a54daeef7141f6ee59089 Mon Sep 17 00:00:00 2001
From: Byeongjee Kang <byeongjee@codechain.io>
Date: Tue, 14 Apr 2020 18:09:41 +0900
Subject: [PATCH] Remove unnecessary initialization of genesis header extra
 data

We gain nothing from initializing extra data of genesis header with
hash of common params, because the check will be done by the same node,
and it will always succeed.
We can just use extra_data written in scheme file.
---
 core/src/client/client.rs |  1 -
 core/src/scheme/scheme.rs | 36 ++----------------------------------
 2 files changed, 2 insertions(+), 35 deletions(-)

diff --git a/core/src/client/client.rs b/core/src/client/client.rs
index 8f6d359bfc..32905d37ce 100644
--- a/core/src/client/client.rs
+++ b/core/src/client/client.rs
@@ -98,7 +98,6 @@ impl Client {
 
         let gb = scheme.genesis_block();
         let chain = BlockChain::new(&gb, db.clone());
-        scheme.check_genesis_common_params(&chain)?;
 
         let engine = scheme.engine.clone();
 
diff --git a/core/src/scheme/scheme.rs b/core/src/scheme/scheme.rs
index 3d656a5c0d..c0ba293442 100644
--- a/core/src/scheme/scheme.rs
+++ b/core/src/scheme/scheme.rs
@@ -17,10 +17,9 @@
 use super::pod_state::PodAccounts;
 use super::seal::Generic as GenericSeal;
 use super::Genesis;
-use crate::blockchain::HeaderProvider;
 use crate::consensus::{CodeChainEngine, NullEngine, Solo, Tendermint};
 use crate::error::{Error, SchemeError};
-use ccrypto::{blake256, BLAKE_NULL_RLP};
+use ccrypto::BLAKE_NULL_RLP;
 use cdb::{AsHashDB, HashDB};
 use ckey::Address;
 use cstate::{Metadata, MetadataAddress, Shard, ShardAddress, StateDB, StateResult};
@@ -169,19 +168,6 @@ impl Scheme {
         Ok(self.initialize_state(db, self.genesis_params())?)
     }
 
-    pub fn check_genesis_common_params<HP: HeaderProvider>(&self, chain: &HP) -> Result<(), Error> {
-        let genesis_header = self.genesis_header();
-        let genesis_header_hash = genesis_header.hash();
-        let header =
-            chain.block_header(&genesis_header_hash).ok_or_else(|| Error::Scheme(SchemeError::InvalidCommonParams))?;
-        let extra_data = header.extra_data();
-        let common_params_hash = blake256(&self.genesis_params().rlp_bytes()).to_vec();
-        if extra_data != &common_params_hash {
-            return Err(Error::Scheme(SchemeError::InvalidCommonParams))
-        }
-        Ok(())
-    }
-
     /// Return the state root for the genesis state, memoising accordingly.
     pub fn state_root(&self) -> H256 {
         *self.state_root_memo.read()
@@ -225,7 +211,7 @@ impl Scheme {
         header.set_number(0);
         header.set_author(self.author);
         header.set_transactions_root(self.transactions_root);
-        header.set_extra_data(blake256(&self.genesis_params().rlp_bytes()).to_vec());
+        header.set_extra_data(self.extra_data.clone());
         header.set_state_root(self.state_root());
         header.set_next_validator_set_hash(BLAKE_NULL_RLP /* This will be calculated from state after https://github.com/CodeChain-io/foundry/issues/142*/);
         header.set_seal({
@@ -288,21 +274,3 @@ fn load_from(s: cjson::scheme::Scheme) -> Result<Scheme, Error> {
 
     Ok(s)
 }
-
-#[cfg(test)]
-mod tests {
-    use ccrypto::Blake;
-
-    use super::*;
-
-    #[test]
-    fn extra_data_of_genesis_header_is_hash_of_common_params() {
-        let scheme = Scheme::new_test();
-        let common_params = scheme.genesis_params();
-        let hash_of_common_params = H256::blake(&common_params.rlp_bytes()).to_vec();
-
-        let genesis_header = scheme.genesis_header();
-        let result = genesis_header.extra_data();
-        assert_eq!(&hash_of_common_params, result);
-    }
-}