deprecate network-threads setting

include/libtorrent/settings_pack.hpp

@@ -1488,6 +1488,7 @@ namespace libtorrent {
 			aio_threads,
 			aio_max,
 
+#if TORRENT_ABI_VERSION == 1
 			// .. note:: This is not implemented
 			//
 			// ``network_threads`` is the number of threads to use to call
@@ -1497,9 +1498,8 @@ namespace libtorrent {
 			// torrents, all encryption for outgoing traffic is done within the
 			// socket send functions, and this will help parallelizing the cost of
 			// SSL encryption as well.
-			network_threads,
+			network_threads TORRENT_DEPRECATED_ENUM,
 
-#if TORRENT_ABI_VERSION == 1
 			// ``ssl_listen`` sets the listen port for SSL connections. If this is
 			// set to 0, no SSL listen port is opened. Otherwise a socket is
 			// opened on this port. This setting is only taken into account when
@@ -1509,6 +1509,7 @@ namespace libtorrent {
 #else
 			// hidden
 			deprecated9,
+			deprecated27,
 #endif
 
 			// ``tracker_backoff`` determines how aggressively to back off from

src/peer_connection.cpp

@@ -5727,7 +5727,6 @@ namespace libtorrent {
 			, "max: %d bytes", max_receive);
 #endif
 
-		// utp sockets aren't thread safe...
 		ADD_OUTSTANDING_ASYNC("peer_connection::on_receive_data");
 		auto conn = self();
 		m_socket->async_read_some(

src/session.cpp

@@ -106,7 +106,6 @@ namespace {
 		set.set_int(settings_pack::checking_mem_usage, 2);
 
 		// don't use any extra threads to do SHA-1 hashing
-		set.set_int(settings_pack::network_threads, 0);
 		set.set_int(settings_pack::aio_threads, 1);
 
 		set.set_int(settings_pack::alert_queue_size, 100);
@@ -273,11 +272,6 @@ namespace {
 		// connect to us if they want to
 		set.set_int(settings_pack::max_failcount, 1);
 
-		// the number of threads to use to call async_write_some
-		// and read_some on peer sockets
-		// this doesn't work. See comment in settings_pack.cpp
-		set.set_int(settings_pack::network_threads, 0);
-
 		// number of disk threads for low level file operations
 		set.set_int(settings_pack::aio_threads, 8);
 

src/settings_pack.cpp

@@ -310,7 +310,7 @@ constexpr int CLOSE_FILE_INTERVAL = 0;
 		SET(predictive_piece_announce, 0, nullptr),
 		SET(aio_threads, 4, &session_impl::update_disk_threads),
 		SET(aio_max, 300, nullptr),
-		SET(network_threads, 0, nullptr),
+		DEPRECATED_SET(network_threads, 0, nullptr),
 		DEPRECATED_SET(ssl_listen, 0, &session_impl::update_ssl_listen),
 		SET(tracker_backoff, 250, nullptr),
 		SET(share_ratio_limit, 200, nullptr),