eth/protocols/snap: fix problems due to idle-but-busy peers

eth/protocols/snap/sync.go

@@ -2248,14 +2248,18 @@ func (s *Syncer) OnAccounts(peer SyncPeer, id uint64, hashes []common.Hash, acco
 	// Whether or not the response is valid, we can mark the peer as idle and
 	// notify the scheduler to assign a new task. If the response is invalid,
 	// we'll drop the peer in a bit.
+	defer func() {
+		s.lock.Lock()
+		defer s.lock.Unlock()
+		if _, ok := s.peers[peer.ID()]; ok {
+			s.accountIdlers[peer.ID()] = struct{}{}
+		}
+		select {
+		case s.update <- struct{}{}:
+		default:
+		}
+	}()
 	s.lock.Lock()
-	if _, ok := s.peers[peer.ID()]; ok {
-		s.accountIdlers[peer.ID()] = struct{}{}
-	}
-	select {
-	case s.update <- struct{}{}:
-	default:
-	}
 	// Ensure the response is for a valid request
 	req, ok := s.accountReqs[id]
 	if !ok {
@@ -2360,14 +2364,18 @@ func (s *Syncer) onByteCodes(peer SyncPeer, id uint64, bytecodes [][]byte) error
 	// Whether or not the response is valid, we can mark the peer as idle and
 	// notify the scheduler to assign a new task. If the response is invalid,
 	// we'll drop the peer in a bit.
+	defer func() {
+		s.lock.Lock()
+		defer s.lock.Unlock()
+		if _, ok := s.peers[peer.ID()]; ok {
+			s.bytecodeIdlers[peer.ID()] = struct{}{}
+		}
+		select {
+		case s.update <- struct{}{}:
+		default:
+		}
+	}()
 	s.lock.Lock()
-	if _, ok := s.peers[peer.ID()]; ok {
-		s.bytecodeIdlers[peer.ID()] = struct{}{}
-	}
-	select {
-	case s.update <- struct{}{}:
-	default:
-	}
 	// Ensure the response is for a valid request
 	req, ok := s.bytecodeReqs[id]
 	if !ok {
@@ -2469,14 +2477,18 @@ func (s *Syncer) OnStorage(peer SyncPeer, id uint64, hashes [][]common.Hash, slo
 	// Whether or not the response is valid, we can mark the peer as idle and
 	// notify the scheduler to assign a new task. If the response is invalid,
 	// we'll drop the peer in a bit.
+	defer func() {
+		s.lock.Lock()
+		defer s.lock.Unlock()
+		if _, ok := s.peers[peer.ID()]; ok {
+			s.storageIdlers[peer.ID()] = struct{}{}
+		}
+		select {
+		case s.update <- struct{}{}:
+		default:
+		}
+	}()
 	s.lock.Lock()
-	if _, ok := s.peers[peer.ID()]; ok {
-		s.storageIdlers[peer.ID()] = struct{}{}
-	}
-	select {
-	case s.update <- struct{}{}:
-	default:
-	}
 	// Ensure the response is for a valid request
 	req, ok := s.storageReqs[id]
 	if !ok {
@@ -2596,14 +2608,18 @@ func (s *Syncer) OnTrieNodes(peer SyncPeer, id uint64, trienodes [][]byte) error
 	// Whether or not the response is valid, we can mark the peer as idle and
 	// notify the scheduler to assign a new task. If the response is invalid,
 	// we'll drop the peer in a bit.
+	defer func() {
+		s.lock.Lock()
+		defer s.lock.Unlock()
+		if _, ok := s.peers[peer.ID()]; ok {
+			s.trienodeHealIdlers[peer.ID()] = struct{}{}
+		}
+		select {
+		case s.update <- struct{}{}:
+		default:
+		}
+	}()
 	s.lock.Lock()
-	if _, ok := s.peers[peer.ID()]; ok {
-		s.trienodeHealIdlers[peer.ID()] = struct{}{}
-	}
-	select {
-	case s.update <- struct{}{}:
-	default:
-	}
 	// Ensure the response is for a valid request
 	req, ok := s.trienodeHealReqs[id]
 	if !ok {
@@ -2691,14 +2707,18 @@ func (s *Syncer) onHealByteCodes(peer SyncPeer, id uint64, bytecodes [][]byte) e
 	// Whether or not the response is valid, we can mark the peer as idle and
 	// notify the scheduler to assign a new task. If the response is invalid,
 	// we'll drop the peer in a bit.
+	defer func() {
+		s.lock.Lock()
+		defer s.lock.Unlock()
+		if _, ok := s.peers[peer.ID()]; ok {
+			s.bytecodeHealIdlers[peer.ID()] = struct{}{}
+		}
+		select {
+		case s.update <- struct{}{}:
+		default:
+		}
+	}()
 	s.lock.Lock()
-	if _, ok := s.peers[peer.ID()]; ok {
-		s.bytecodeHealIdlers[peer.ID()] = struct{}{}
-	}
-	select {
-	case s.update <- struct{}{}:
-	default:
-	}
 	// Ensure the response is for a valid request
 	req, ok := s.bytecodeHealReqs[id]
 	if !ok {