From 6ad54b98407d0e80d335498a6848135ed1ea8b30 Mon Sep 17 00:00:00 2001
From: Gary Yu <gairy.yu@gmail.com>
Date: Mon, 1 Oct 2018 11:51:15 +0800
Subject: [PATCH] fix: mutex dead lock between difficulty_iter and
 txhashset_write (#1617)

fix #1611
---
 chain/src/chain.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/chain/src/chain.rs b/chain/src/chain.rs
index d56ae6c45..2f8d148e7 100644
--- a/chain/src/chain.rs
+++ b/chain/src/chain.rs
@@ -963,8 +963,8 @@ impl Chain {
 	/// running backward. Specialized to return information pertaining to block
 	/// difficulty calculation (timestamp and previous difficulties).
 	pub fn difficulty_iter(&self) -> store::DifficultyIter {
-		let head = self.head.lock().unwrap();
 		let batch = self.store.batch().unwrap();
+		let head = self.head.lock().unwrap();
 		store::DifficultyIter::from(head.last_block_h, batch)
 	}