From 7573f6a556bab250b93c479e4b4e1fbf09859729 Mon Sep 17 00:00:00 2001
From: AntiochP <30642645+antiochp@users.noreply.github.com>
Date: Tue, 21 Nov 2017 22:28:31 -0500
Subject: [PATCH] use read lock over write lock where possible (#363)

fix issue with sync starting twice
---
 grin/src/adapters.rs |  4 ++--
 p2p/src/server.rs    | 18 ++++++++++++------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/grin/src/adapters.rs b/grin/src/adapters.rs
index ffbc81f5e..3be2cdd42 100644
--- a/grin/src/adapters.rs
+++ b/grin/src/adapters.rs
@@ -259,7 +259,7 @@ impl NetAdapter for NetToChainAdapter {
 		);
 
 		if diff.into_num() > 0 {
-			let peers = self.connected_peers.write().unwrap();
+			let peers = self.connected_peers.read().unwrap();
 			if let Some(peer) = peers.get(&addr) {
 				let mut peer = peer.write().unwrap();
 				peer.info.total_difficulty = diff;
@@ -293,7 +293,7 @@ impl NetToChainAdapter {
 			.name("syncer".to_string())
 			.spawn(move || {
 				let res = arc_sync.run();
-				if let Err(e) = arc_sync.run() {
+				if let Err(e) = res {
 					panic!("Error during sync, aborting: {:?}", e);
 				}
 			});
diff --git a/p2p/src/server.rs b/p2p/src/server.rs
index 6a63a58c4..d4e030e38 100644
--- a/p2p/src/server.rs
+++ b/p2p/src/server.rs
@@ -278,6 +278,10 @@ impl Server {
 			let p = p.read().unwrap();
 			p.info.total_difficulty.clone()
 		});
+
+		// TODO we should shuffle here
+		// we want a random peer with highest total_difficulty
+
 		let peer = peers.last().unwrap();
 		Some(peer.clone())
 	}
@@ -329,16 +333,16 @@ impl Server {
 
 	/// Number of peers we're currently connected to.
 	pub fn peer_count(&self) -> u32 {
-		self.peers.read().unwrap().len() as u32
+		self.all_peers().len() as u32
 	}
 
 	/// Stops the server. Disconnect from all peers at the same time.
 	pub fn stop(self) {
 		info!(LOGGER, "calling stop on server");
 		let peers = self.all_peers();
-		for p in peers {
-			let p = p.write().unwrap();
-			p.stop();
+		for peer in peers {
+			let peer = peer.read().unwrap();
+			peer.stop();
 		}
 		self.stop.into_inner().unwrap().send(()).unwrap();
 	}
@@ -357,8 +361,10 @@ where
 		adapter.peer_connected(&peer.info);
 		let addr = peer.info.addr.clone();
 		let apeer = Arc::new(RwLock::new(peer));
-		let mut peers = peers.write().unwrap();
-		peers.insert(addr, apeer.clone());
+		{
+			let mut peers = peers.write().unwrap();
+			peers.insert(addr, apeer.clone());
+		}
 		Ok((conn, apeer))
 	});
 	Box::new(peer_add)