ethcore/test_helpers: fix deadlock caused by double read lock

ethcore/src/test_helpers/test_client.rs

@@ -353,11 +353,12 @@ impl TestBlockChainClient {
  }
 
  fn block_hash(&self, id: BlockId) -> Option<H256> {
+ let numbers = self.numbers.read();
  match id {
  BlockId::Hash(hash) => Some(hash),
- BlockId::Number(n) => self.numbers.read().get(&(n as usize)).cloned(),
- BlockId::Earliest => self.numbers.read().get(&0).cloned(),
- BlockId::Latest => self.numbers.read().get(&(self.numbers.read().len() - 1)).cloned()
+ BlockId::Number(n) => numbers.get(&(n as usize)).cloned(),
+ BlockId::Earliest => numbers.get(&0).cloned(),
+ BlockId::Latest => numbers.get(&(numbers.len() - 1)).cloned()
  }
  }
 
@@ -488,17 +489,21 @@ impl AccountData for TestBlockChainClient {}
 impl ChainInfo for TestBlockChainClient {
  fn chain_info(&self) -> BlockChainInfo {
  let number = self.blocks.read().len() as BlockNumber - 1;
+ let last_hash = self.last_hash.read();
+ let difficulty = self.difficulty.read();
+ let ancient_block = self.ancient_block.read();
+ let first_block = self.first_block.read();
  BlockChainInfo {
- total_difficulty: *self.difficulty.read(),
- pending_total_difficulty: *self.difficulty.read(),
+ total_difficulty: *difficulty,
+ pending_total_difficulty: *difficulty,
  genesis_hash: self.genesis_hash.clone(),
- best_block_hash: self.last_hash.read().clone(),
+ best_block_hash: last_hash.clone(),
  best_block_number: number,
  best_block_timestamp: number,
- first_block_hash: self.first_block.read().as_ref().map(|x| x.0),
- first_block_number: self.first_block.read().as_ref().map(|x| x.1),
- ancient_block_hash: self.ancient_block.read().as_ref().map(|x| x.0),
- ancient_block_number: self.ancient_block.read().as_ref().map(|x| x.1)
+ first_block_hash: first_block.as_ref().map(|x| x.0),
+ first_block_number: first_block.as_ref().map(|x| x.1),
+ ancient_block_hash: ancient_block.as_ref().map(|x| x.0),
+ ancient_block_number: ancient_block.as_ref().map(|x| x.1)
  }
  }
 }