[Net] ENet poll now only service the connection once.

It used to call `enet_host_service` until all events were consumed, but
that also meant constantly polling the connection leading to potentially
unbounded processing time.

It now only service the connection once, and instead consumes all the
retrieved events via `enet_host_check_events`.

1 files changed, 52 insertions, 36 deletions

diff --git a/modules/enet/enet_connection.cpp b/modules/enet/enet_connection.cpp
index e833264d6a..62f03b444b 100644
--- a/modules/enet/enet_connection.cpp
+++ b/modules/enet/enet_connection.cpp
@@ -117,58 +117,36 @@ Ref<ENetPacketPeer> ENetConnection::connect_to_host(const String &p_address, int
 	return out;
 }
 
-ENetConnection::EventType ENetConnection::service(int p_timeout, Event &r_event) {
-	ERR_FAIL_COND_V_MSG(!host, EVENT_ERROR, "The ENetConnection instance isn't currently active.");
-	ERR_FAIL_COND_V(r_event.peer.is_valid(), EVENT_ERROR);
-
-	// Drop peers that have already been disconnected.
-	// NOTE: Forcibly disconnected peers (i.e. peers disconnected via
-	// enet_peer_disconnect*) do not trigger DISCONNECTED events.
-	List<Ref<ENetPacketPeer>>::Element *E = peers.front();
-	while (E) {
-		if (!E->get()->is_active()) {
-			peers.erase(E->get());
-		}
-		E = E->next();
-	}
-
-	ENetEvent event;
-	int ret = enet_host_service(host, &event, p_timeout);
-
-	if (ret < 0) {
-		return EVENT_ERROR;
-	} else if (ret == 0) {
-		return EVENT_NONE;
-	}
-	switch (event.type) {
+ENetConnection::EventType ENetConnection::_parse_event(const ENetEvent &p_event, Event &r_event) {
+	switch (p_event.type) {
 		case ENET_EVENT_TYPE_CONNECT: {
-			if (event.peer->data == nullptr) {
-				Ref<ENetPacketPeer> pp = memnew(ENetPacketPeer(event.peer));
+			if (p_event.peer->data == nullptr) {
+				Ref<ENetPacketPeer> pp = memnew(ENetPacketPeer(p_event.peer));
 				peers.push_back(pp);
 			}
-			r_event.peer = Ref<ENetPacketPeer>((ENetPacketPeer *)event.peer->data);
-			r_event.data = event.data;
+			r_event.peer = Ref<ENetPacketPeer>((ENetPacketPeer *)p_event.peer->data);
+			r_event.data = p_event.data;
 			return EVENT_CONNECT;
 		} break;
 		case ENET_EVENT_TYPE_DISCONNECT: {
 			// A peer disconnected.
-			if (event.peer->data != nullptr) {
-				Ref<ENetPacketPeer> pp = Ref<ENetPacketPeer>((ENetPacketPeer *)event.peer->data);
+			if (p_event.peer->data != nullptr) {
+				Ref<ENetPacketPeer> pp = Ref<ENetPacketPeer>((ENetPacketPeer *)p_event.peer->data);
 				pp->_on_disconnect();
 				peers.erase(pp);
 				r_event.peer = pp;
-				r_event.data = event.data;
+				r_event.data = p_event.data;
 				return EVENT_DISCONNECT;
 			}
 			return EVENT_ERROR;
 		} break;
 		case ENET_EVENT_TYPE_RECEIVE: {
 			// Packet reveived.
-			if (event.peer->data != nullptr) {
-				Ref<ENetPacketPeer> pp = Ref<ENetPacketPeer>((ENetPacketPeer *)event.peer->data);
-				r_event.peer = Ref<ENetPacketPeer>((ENetPacketPeer *)event.peer->data);
-				r_event.channel_id = event.channelID;
-				r_event.packet = event.packet;
+			if (p_event.peer->data != nullptr) {
+				Ref<ENetPacketPeer> pp = Ref<ENetPacketPeer>((ENetPacketPeer *)p_event.peer->data);
+				r_event.peer = Ref<ENetPacketPeer>((ENetPacketPeer *)p_event.peer->data);
+				r_event.channel_id = p_event.channelID;
+				r_event.packet = p_event.packet;
 				return EVENT_RECEIVE;
 			}
 			return EVENT_ERROR;
@@ -180,6 +158,44 @@ ENetConnection::EventType ENetConnection::service(int p_timeout, Event &r_event)
 	}
 }
 
+ENetConnection::EventType ENetConnection::service(int p_timeout, Event &r_event) {
+	ERR_FAIL_COND_V_MSG(!host, EVENT_ERROR, "The ENetConnection instance isn't currently active.");
+	ERR_FAIL_COND_V(r_event.peer.is_valid(), EVENT_ERROR);
+
+	// Drop peers that have already been disconnected.
+	// NOTE: Forcibly disconnected peers (i.e. peers disconnected via
+	// enet_peer_disconnect*) do not trigger DISCONNECTED events.
+	List<Ref<ENetPacketPeer>>::Element *E = peers.front();
+	while (E) {
+		if (!E->get()->is_active()) {
+			peers.erase(E->get());
+		}
+		E = E->next();
+	}
+
+	ENetEvent event;
+	int ret = enet_host_service(host, &event, p_timeout);
+
+	if (ret < 0) {
+		return EVENT_ERROR;
+	} else if (ret == 0) {
+		return EVENT_NONE;
+	}
+	return _parse_event(event, r_event);
+}
+
+int ENetConnection::check_events(EventType &r_type, Event &r_event) {
+	ERR_FAIL_COND_V_MSG(!host, -1, "The ENetConnection instance isn't currently active.");
+	ENetEvent event;
+	int ret = enet_host_check_events(host, &event);
+	if (ret < 0) {
+		r_type = EVENT_ERROR;
+		return ret;
+	}
+	r_type = _parse_event(event, r_event);
+	return ret;
+}
+
 void ENetConnection::flush() {
 	ERR_FAIL_COND_MSG(!host, "The ENetConnection instance isn't currently active.");
 	enet_host_flush(host);