From fe89fcb27493e94b6fb136800270032fd859d751 Mon Sep 17 00:00:00 2001
From: Nazar Mokrynskyi <nazar@mokrynskyi.com>
Date: Fri, 26 Aug 2022 01:59:40 +0300
Subject: [PATCH] Actually fix major sync detection

---
 client/network/common/src/sync.rs |  2 ++
 client/network/src/service.rs     | 13 +++++++------
 client/network/sync/src/lib.rs    | 20 ++++++++++----------
 3 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/client/network/common/src/sync.rs b/client/network/common/src/sync.rs
index 2ee8f8c51814b..a7c22ce76e73a 100644
--- a/client/network/common/src/sync.rs
+++ b/client/network/common/src/sync.rs
@@ -67,6 +67,8 @@ pub struct SyncStatus<Block: BlockT> {
 	pub state: SyncState,
 	/// Target sync block number.
 	pub best_seen_block: Option<NumberFor<Block>>,
+	/// Are we actively catching up with the chain?
+	pub is_major_syncing: bool,
 	/// Number of peers participating in syncing.
 	pub num_peers: u32,
 	/// Number of blocks queued for import
diff --git a/client/network/src/service.rs b/client/network/src/service.rs
index 162b9c6a30491..1656d38179a9b 100644
--- a/client/network/src/service.rs
+++ b/client/network/src/service.rs
@@ -71,7 +71,7 @@ use sc_network_common::{
 		NotificationSender as NotificationSenderT, NotificationSenderError,
 		NotificationSenderReady as NotificationSenderReadyT, Signature, SigningError,
 	},
-	sync::{SyncState, SyncStatus},
+	sync::SyncStatus,
 };
 use sc_peerset::PeersetHandle;
 use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedReceiver, TracingUnboundedSender};
@@ -1938,11 +1938,12 @@ where
 			*this.external_addresses.lock() = external_addresses;
 		}
 
-		let is_major_syncing =
-			match this.network_service.behaviour_mut().user_protocol_mut().sync_state().state {
-				SyncState::Idle => false,
-				SyncState::Downloading => true,
-			};
+		let is_major_syncing = this
+			.network_service
+			.behaviour_mut()
+			.user_protocol_mut()
+			.sync_state()
+			.is_major_syncing;
 
 		this.tx_handler_controller.set_gossip_enabled(!is_major_syncing);
 
diff --git a/client/network/sync/src/lib.rs b/client/network/sync/src/lib.rs
index aae5f4de353fe..960b32061230e 100644
--- a/client/network/sync/src/lib.rs
+++ b/client/network/sync/src/lib.rs
@@ -389,8 +389,10 @@ where
 
 	/// Returns the current sync status.
 	fn status(&self) -> SyncStatus<B> {
-		let best_seen = self.best_seen();
-		let sync_state = if let Some(n) = best_seen {
+		let median_seen = self.median_seen();
+		let best_seen_block =
+			median_seen.and_then(|median| (median > self.best_queued_number).then_some(median));
+		let sync_state = if let Some(n) = median_seen {
 			// A chain is classified as downloading if the provided best block is
 			// more than `MAJOR_SYNC_BLOCKS` behind the best block.
 			let best_block = self.client.info().best_number;
@@ -414,9 +416,12 @@ where
 			_ => None,
 		};
 
+		let is_major_syncing = matches!(sync_state, SyncState::Downloading);
+
 		SyncStatus {
 			state: sync_state,
-			best_seen_block: best_seen,
+			best_seen_block,
+			is_major_syncing,
 			num_peers: self.peers.len() as u32,
 			queued_blocks: self.queue_blocks.len() as u32,
 			state_sync: self.state_sync.as_ref().map(|s| s.progress()),
@@ -1720,7 +1725,7 @@ where
 	}
 
 	/// Returns the best seen block number if we don't have that block yet, `None` otherwise.
-	fn best_seen(&self) -> Option<NumberFor<B>> {
+	fn median_seen(&self) -> Option<NumberFor<B>> {
 		let mut best_seens = self.peers.values().map(|p| p.best_number).collect::<Vec<_>>();
 
 		if best_seens.is_empty() {
@@ -1729,12 +1734,7 @@ where
 			let middle = best_seens.len() / 2;
 
 			// Not the "perfect median" when we have an even number of peers.
-			let median = *best_seens.select_nth_unstable(middle).1;
-			if median > self.best_queued_number {
-				Some(median)
-			} else {
-				None
-			}
+			Some(*best_seens.select_nth_unstable(middle).1)
 		}
 	}