From a015d8231ecc77d1fb27b1923f4cf9e55acb2aaf Mon Sep 17 00:00:00 2001
From: Conner Fromknecht <conner@lightning.engineering>
Date: Mon, 15 Apr 2019 20:34:46 -0700
Subject: [PATCH] netsync/manager: split out handlePeerDone helpers

Preemptively splits out portions of the handlePeerDone method so that
they can be used in the stall detection logic added in the next commit.
---
 netsync/manager.go | 44 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 10 deletions(-)

diff --git a/netsync/manager.go b/netsync/manager.go
index 8444c898..37c26707 100644
--- a/netsync/manager.go
+++ b/netsync/manager.go
@@ -418,6 +418,19 @@ func (sm *SyncManager) handleDonePeerMsg(peer *peerpkg.Peer) {
 
 	log.Infof("Lost peer %s", peer)
 
+	sm.clearRequestedState(state)
+
+	if peer == sm.syncPeer {
+		// Update the sync peer. The server has already disconnected the
+		// peer before signaling to the sync manager.
+		sm.updateSyncPeer(false)
+	}
+}
+
+// clearRequestedState wipes all expected transactions and blocks from the sync
+// manager's requested maps that were requested under a peer's sync state, This
+// allows them to be rerequested by a subsequent sync peer.
+func (sm *SyncManager) clearRequestedState(state *peerSyncState) {
 	// Remove requested transactions from the global map so that they will
 	// be fetched from elsewhere next time we get an inv.
 	for txHash := range state.requestedTxns {
@@ -431,18 +444,29 @@ func (sm *SyncManager) handleDonePeerMsg(peer *peerpkg.Peer) {
 	for blockHash := range state.requestedBlocks {
 		delete(sm.requestedBlocks, blockHash)
 	}
+}
 
-	// Attempt to find a new peer to sync from if the quitting peer is the
-	// sync peer.  Also, reset the headers-first state if in headers-first
-	// mode so
-	if sm.syncPeer == peer {
-		sm.syncPeer = nil
-		if sm.headersFirstMode {
-			best := sm.chain.BestSnapshot()
-			sm.resetHeaderState(&best.Hash, best.Height)
-		}
-		sm.startSync()
+// updateSyncPeer choose a new sync peer to replace the current one. If
+// dcSyncPeer is true, this method will also disconnect the current sync peer.
+// If we are in header first mode, any header state related to prefetching is
+// also reset in preparation for the next sync peer.
+func (sm *SyncManager) updateSyncPeer(dcSyncPeer bool) {
+	log.Infof("Updating sync peer, no progress since: %v",
+		time.Since(sm.lastProgressTime))
+
+	// First, disconnect the current sync peer if requested.
+	if dcSyncPeer {
+		sm.syncPeer.Disconnect()
 	}
+
+	// Reset any header state before we choose our next active sync peer.
+	if sm.headersFirstMode {
+		best := sm.chain.BestSnapshot()
+		sm.resetHeaderState(&best.Hash, best.Height)
+	}
+
+	sm.syncPeer = nil
+	sm.startSync()
 }
 
 // handleTxMsg handles transaction messages from all peers.