removed redundant fork choice abstraction (#10849)

ethcore/src/client/client.rs

@@ -40,7 +40,7 @@ use types::encoded;
 use types::filter::Filter;
 use types::log_entry::LocalizedLogEntry;
 use types::receipt::{Receipt, LocalizedReceipt};
-use types::{BlockNumber, header::{Header, ExtendedHeader}};
+use types::{BlockNumber, header::Header};
 use vm::{EnvInfo, LastHashes};
 use hash_db::EMPTY_PREFIX;
 use block::{LockedBlock, Drain, ClosedBlock, OpenBlock, enact_verified, SealedBlock};
@@ -502,32 +502,24 @@ impl Importer {
 		let traces = block.traces.drain();
 		let best_hash = chain.best_block_hash();
 
-		let new = ExtendedHeader {
+		let new_total_difficulty = {
-			header: header.clone(),
+			let parent_total_difficulty = chain.block_details(&parent)
-			is_finalized,
+				.expect("Parent block is in the database; qed")
-			parent_total_difficulty: chain.block_details(&parent).expect("Parent block is in the database; qed").total_difficulty
+				.total_difficulty;
+			parent_total_difficulty + header.difficulty()
 		};
 
-		let best = {
+		let best_total_difficulty = chain.block_details(&best_hash)
-			let header = chain.block_header_data(&best_hash)
+			.expect("Best block is in the database; qed")
-				.expect("Best block is in the database; qed")
+			.total_difficulty;
-				.decode()
-				.expect("Stored block header is valid RLP; qed");
-			let details = chain.block_details(&best_hash)
-				.expect("Best block is in the database; qed");
-
-			ExtendedHeader {
-				parent_total_difficulty: details.total_difficulty - *header.difficulty(),
-				is_finalized: details.is_finalized,
-				header,
-			}
-		};
 
 		let route = chain.tree_route(best_hash, *parent).expect("forks are only kept when it has common ancestors; tree route from best to prospective's parent always exists; qed");
 		let fork_choice = if route.is_from_route_finalized {
 			ForkChoice::Old
+		} else if new_total_difficulty > best_total_difficulty {
+			ForkChoice::New
 		} else {
-			self.engine.fork_choice(&new, &best)
+			ForkChoice::Old
 		};
 
 		// CHECK! I *think* this is fine, even if the state_root is equal to another

ethcore/src/engines/authority_round/mod.rs

@@ -1592,10 +1592,6 @@ impl Engine for AuthorityRound {
 		}
 	}
 
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> super::ForkChoice {
-		super::total_difficulty_fork_choice(new, current)
-	}
-
 	fn ancestry_actions(&self, header: &Header, ancestry: &mut dyn Iterator<Item=ExtendedHeader>) -> Vec<AncestryAction> {
 		let finalized = self.build_finality(
 			header,

ethcore/src/engines/basic_authority.rs

@@ -27,7 +27,7 @@ use error::{BlockError, Error};
 use ethjson;
 use client::EngineClient;
 use machine::{AuxiliaryData, Call, Machine};
-use types::header::{Header, ExtendedHeader};
+use types::header::Header;
 use super::validator_set::{ValidatorSet, SimpleList, new_validator_set};
 
 /// `BasicAuthority` params.
@@ -208,10 +208,6 @@ impl Engine for BasicAuthority {
 	fn snapshot_components(&self) -> Option<Box<dyn (::snapshot::SnapshotComponents)>> {
 		None
 	}
-
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> super::ForkChoice {
-		super::total_difficulty_fork_choice(new, current)
-	}
 }
 
 #[cfg(test)]

ethcore/src/engines/clique/mod.rs

@@ -83,7 +83,7 @@ use super::signer::EngineSigner;
 use unexpected::{Mismatch, OutOfBounds};
 use time_utils::CheckedSystemTime;
 use types::BlockNumber;
-use types::header::{ExtendedHeader, Header};
+use types::header::Header;
 
 use self::block_state::CliqueBlockState;
 use self::params::CliqueParams;
@@ -766,10 +766,6 @@ impl Engine for Clique {
 		header_timestamp >= parent_timestamp.saturating_add(self.period)
 	}
 
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> super::ForkChoice {
-		super::total_difficulty_fork_choice(new, current)
-	}
-
 	// Clique uses the author field for voting, the real author is hidden in the `extra_data` field.
 	// So when executing tx's (like in `enact()`) we want to use the executive author
 	fn executive_author(&self, header: &Header) -> Result<Address, Error> {

ethcore/src/engines/instant_seal.rs

@@ -16,7 +16,7 @@
 
 use engines::{Engine, Seal, SealingState};
 use machine::Machine;
-use types::header::{Header, ExtendedHeader};
+use types::header::Header;
 use block::ExecutedBlock;
 use error::Error;
 
@@ -87,10 +87,6 @@ impl Engine for InstantSeal {
 	fn is_timestamp_valid(&self, header_timestamp: u64, parent_timestamp: u64) -> bool {
 		header_timestamp >= parent_timestamp
 	}
-
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> super::ForkChoice {
-		super::total_difficulty_fork_choice(new, current)
-	}
 }
 
 #[cfg(test)]

ethcore/src/engines/mod.rs

@@ -469,9 +469,6 @@ pub trait Engine: Sync + Send {
 		Vec::new()
 	}
 
-	/// Check whether the given new block is the best block, after finalization check.
-	fn fork_choice(&self, new: &ExtendedHeader, best: &ExtendedHeader) -> ForkChoice;
-
 	/// Returns author should used when executing tx's for this block.
 	fn executive_author(&self, header: &Header) -> Result<Address, Error> {
 		Ok(*header.author())
@@ -550,15 +547,6 @@ pub trait Engine: Sync + Send {
 	}
 }
 
-/// Check whether a given block is the best block based on the default total difficulty rule.
-pub fn total_difficulty_fork_choice(new: &ExtendedHeader, best: &ExtendedHeader) -> ForkChoice {
-	if new.total_score() > best.total_score() {
-		ForkChoice::New
-	} else {
-		ForkChoice::Old
-	}
-}
-
 /// Verifier for all blocks within an epoch with self-contained state.
 pub trait EpochVerifier: Send + Sync {
 	/// Lightly verify the next block header.

ethcore/src/engines/null_engine.rs

@@ -19,7 +19,7 @@ use engines::block_reward::{self, RewardKind};
 use ethereum_types::U256;
 use machine::Machine;
 use types::BlockNumber;
-use types::header::{Header, ExtendedHeader};
+use types::header::Header;
 use block::ExecutedBlock;
 use error::Error;
 
@@ -101,8 +101,4 @@ impl Engine for NullEngine {
 	fn snapshot_components(&self) -> Option<Box<dyn (::snapshot::SnapshotComponents)>> {
 		Some(Box::new(::snapshot::PowSnapshot::new(10000, 10000)))
 	}
-
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> super::ForkChoice {
-		super::total_difficulty_fork_choice(new, current)
-	}
 }

ethcore/src/ethereum/ethash.rs

@@ -23,7 +23,7 @@ use ethereum_types::{H256, H64, U256};
 use ethjson;
 use hash::{KECCAK_EMPTY_LIST_RLP};
 use rlp::Rlp;
-use types::header::{Header, ExtendedHeader};
+use types::header::Header;
 use types::BlockNumber;
 use unexpected::{OutOfBounds, Mismatch};
 
@@ -380,10 +380,6 @@ impl Engine for Arc<Ethash> {
 	fn snapshot_components(&self) -> Option<Box<dyn (::snapshot::SnapshotComponents)>> {
 		Some(Box::new(::snapshot::PowSnapshot::new(SNAPSHOT_BLOCKS, MAX_SNAPSHOT_BLOCKS)))
 	}
-
-	fn fork_choice(&self, new: &ExtendedHeader, current: &ExtendedHeader) -> engines::ForkChoice {
-		engines::total_difficulty_fork_choice(new, current)
-	}
 }
 
 impl Ethash {