Merge pull request #1401 from ethcore/sfedgecase

Shortcut SF condition when canon known

ethcore/src/block.rs

@@ -288,6 +288,7 @@ impl<'x> OpenBlock<'x> {
 	/// Get the environment info concerning this block.
 	pub fn env_info(&self) -> EnvInfo {
 		// TODO: memoise.
+		const SOFT_FORK_BLOCK: u64 = 1775000;
 		EnvInfo {
 			number: self.block.base.header.number,
 			author: self.block.base.header.author.clone(),
@@ -296,7 +297,7 @@ impl<'x> OpenBlock<'x> {
 			last_hashes: self.last_hashes.clone(),		// TODO: should be a reference.
 			gas_used: self.block.receipts.last().map_or(U256::zero(), |r| r.gas_used),
 			gas_limit: self.block.base.header.gas_limit.clone(),
-			dao_rescue_block_gas_limit: if self.block.base.header.number == 1760000 { Some(self.block.base.header.gas_limit) } else { self.dao_rescue_block_gas_limit },
+			dao_rescue_block_gas_limit: if self.block.base.header.number == SOFT_FORK_BLOCK { Some(self.block.base.header.gas_limit) } else { self.dao_rescue_block_gas_limit },
 		}
 	}
 

ethcore/src/client/mod.rs

@@ -225,14 +225,19 @@ pub trait BlockChainClient : Sync + Send {
 		}
 	}
 
-
-	/// Get `Some` gas limit of block 1_760_000, or `None` if chain is not yet that long.
+	/// Get `Some` gas limit of SOFT_FORK_BLOCK, or `None` if chain is not yet that long.
 	fn dao_rescue_block_gas_limit(&self, chain_hash: H256) -> Option<U256> {
+		const SOFT_FORK_BLOCK: u64 = 1775000;
+		// shortcut if the canon chain is already known.
+		if self.chain_info().best_block_number > SOFT_FORK_BLOCK + 1000 {
+			return self.block_header(BlockID::Number(SOFT_FORK_BLOCK)).map(|header| HeaderView::new(&header).gas_limit());
+		}
+		// otherwise check according to `chain_hash`.
 		if let Some(mut header) = self.block_header(BlockID::Hash(chain_hash)) {
-			if HeaderView::new(&header).number() < 1_760_000 {
+			if HeaderView::new(&header).number() < SOFT_FORK_BLOCK {
 				None
 			} else {
-				while HeaderView::new(&header).number() != 1_760_000 {
+				while HeaderView::new(&header).number() != SOFT_FORK_BLOCK {
 					header = self.block_header(BlockID::Hash(HeaderView::new(&header).parent_hash())).expect("chain is complete; parent of chain entry must be in chain; qed");
 				}
 				Some(HeaderView::new(&header).gas_limit())

ethcore/src/env_info.rs

@@ -40,7 +40,7 @@ pub struct EnvInfo {
 	/// The gas used.
 	pub gas_used: U256,
 
-	/// Block gas limit at DAO rescue block #1760000 or None if not yet there.
+	/// Block gas limit at DAO rescue block SOFT_FORK_BLOCK or None if not yet there.
 	pub dao_rescue_block_gas_limit: Option<U256>,
 }