Fixing expect calls

ethcore/src/blockchain/blockchain.rs

@@ -52,15 +52,15 @@ pub trait BlockProvider {
 
 	/// Get the number of the first block.
 	fn first_block_number(&self) -> Option<BlockNumber> {
-		self.first_block().map(|b| self.block_number(&b).expect("First block always stored; qed"))
+		self.first_block().map(|b| self.block_number(&b).expect("First block is always set to an existing block or `None`. Existing block always has a number; qed"))
 	}
 
 	/// Get the best block of an first block sequence if there is a gap.
 	fn best_ancient_block(&self) -> Option<H256>;
 
 	/// Get the number of the first block.
 	fn best_ancient_number(&self) -> Option<BlockNumber> {
-		self.best_ancient_block().map(|h| self.block_number(&h).expect("Best ancient block always stored; qed"))
+		self.best_ancient_block().map(|h| self.block_number(&h).expect("Ancient block is always set to an existing block or `None`. Existing block always has a number; qed"))
 	}
 	/// Get raw block data
 	fn block(&self, hash: &H256) -> Option<Bytes>;
@@ -169,10 +169,14 @@ impl bc::group::BloomGroupDatabase for BlockChain {
 pub struct BlockChain {
 	// All locks must be captured in the order declared here.
 	blooms_config: bc::Config,
-	first_block: Option<H256>,
 
 	best_block: RwLock<BestBlock>,
+	// Stores best block of the first uninterrupted sequence of blocks. `None` if there are no gaps.
+	// Only updated with `insert_unordered_block`.
 	best_ancient_block: RwLock<Option<BestAncientBlock>>,
+	// Stores the last block of the last sequence of blocks. `None` if there are no gaps.
+	// This is calculated on start and does not get updated.
+	first_block: Option<H256>,
 
 	// block cache
 	block_headers: RwLock<HashMap<H256, Bytes>>,

sync/src/chain.rs

@@ -571,12 +571,14 @@ impl ChainSync {
 			let mut downloader = match block_set {
 				BlockSet::NewBlocks => &mut self.new_blocks,
 				BlockSet::OldBlocks => {
-					if self.old_blocks.is_none() {
-						trace!(target: "sync", "Ignored block headers while block download is inactive");
-						self.continue_sync(io);
-						return Ok(());
+					match self.old_blocks {
+						None => {
+							trace!(target: "sync", "Ignored block headers while block download is inactive");
+							self.continue_sync(io);
+							return Ok(());
+						},
+						Some(ref mut blocks) => blocks,
 					}
-					self.old_blocks.as_mut().expect("Checked with condition above; qed")
 				}
 			};
 			downloader.import_headers(io, r, expected_hash)
@@ -625,13 +627,13 @@ impl ChainSync {
 			let result = {
 				let mut downloader = match block_set {
 					BlockSet::NewBlocks => &mut self.new_blocks,
-					BlockSet::OldBlocks => {
-						if self.old_blocks.is_none() {
+					BlockSet::OldBlocks => match self.old_blocks {
+						None => {
 							trace!(target: "sync", "Ignored block headers while block download is inactive");
 							self.continue_sync(io);
 							return Ok(());
-						}
-						self.old_blocks.as_mut().expect("Checked with condition above; qed")
+						},
+						Some(ref mut blocks) => blocks,
 					}
 				};
 				downloader.import_bodies(io, r)
@@ -679,13 +681,13 @@ impl ChainSync {
 			let result = {
 				let mut downloader = match block_set {
 					BlockSet::NewBlocks => &mut self.new_blocks,
-					BlockSet::OldBlocks => {
-						if self.old_blocks.is_none() {
+					BlockSet::OldBlocks => match self.old_blocks {
+						None => {
 							trace!(target: "sync", "Ignored block headers while block download is inactive");
 							self.continue_sync(io);
 							return Ok(());
-						}
-						self.old_blocks.as_mut().expect("Checked with condition above; qed")
+						},
+						Some(ref mut blocks) => blocks,
 					}
 				};
 				downloader.import_receipts(io, r)