From fae1305b5783ce7a59ab1d4f44e199bd2bda1f45 Mon Sep 17 00:00:00 2001
From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Thu, 5 Nov 2015 15:32:51 +0100
Subject: [PATCH] let the server wait a little more efficiently

---
 src/app/IntervalTimer.hpp  |  8 +++++++-
 src/server/Server.hpp      |  5 +++++
 src/server/ServerState.cpp |  9 +++++++++
 src/server/net.cpp         | 26 ++++++++++++++++++++++++++
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/app/IntervalTimer.hpp b/src/app/IntervalTimer.hpp
index ee84c65..2f465ad 100644
--- a/src/app/IntervalTimer.hpp
+++ b/src/app/IntervalTimer.hpp
@@ -35,7 +35,7 @@ public:
 	}
 	/// true if an interval boundary was passed by the last call to Update()
 	bool Hit() const noexcept {
-		return Running() && mod(value, intv) < last_dt;
+		return Running() && IntervalElapsed() < last_dt;
 	}
 	bool HitOnce() const noexcept {
 		return Running() && value >= intv;
@@ -46,6 +46,12 @@ public:
 	Time Interval() const noexcept {
 		return intv;
 	}
+	Time IntervalElapsed() const noexcept {
+		return mod(value, intv);
+	}
+	Time IntervalRemain() const noexcept {
+		return intv - IntervalElapsed();
+	}
 	int Iteration() const noexcept {
 		return value / intv;
 	}
diff --git a/src/server/Server.hpp b/src/server/Server.hpp
index 3bffafc..40905c8 100644
--- a/src/server/Server.hpp
+++ b/src/server/Server.hpp
@@ -29,6 +29,10 @@ public:
 	Server(const Config::Network &, World &, const World::Config &, const WorldSave &);
 	~Server();
 
+	// wait for data to arrive for at most dt milliseconds
+	void Wait(int dt) noexcept;
+	// true if there's data waiting to be handled
+	bool Ready() noexcept;
 	void Handle();
 
 	void Update(int dt);
@@ -63,6 +67,7 @@ private:
 private:
 	UDPsocket serv_sock;
 	UDPpacket serv_pack;
+	SDLNet_SocketSet serv_set;
 	std::list<ClientConnection> clients;
 
 	World &world;
diff --git a/src/server/ServerState.cpp b/src/server/ServerState.cpp
index 0bec391..7e645ed 100644
--- a/src/server/ServerState.cpp
+++ b/src/server/ServerState.cpp
@@ -58,6 +58,15 @@ void ServerState::Handle(const SDL_Event &event) {
 
 void ServerState::Update(int dt) {
 	loop_timer.Update(dt);
+	if (!loop_timer.HitOnce() && loop_timer.IntervalRemain() > 1) {
+		server.Wait(loop_timer.IntervalRemain() - 1);
+		return;
+	}
+	if (dt == 0 && !server.Ready()) {
+		// effectively wait in a spin loop
+		return;
+	}
+
 	server.Handle();
 	int world_dt = 0;
 	while (loop_timer.HitOnce()) {
diff --git a/src/server/net.cpp b/src/server/net.cpp
index 47342ff..7947c22 100644
--- a/src/server/net.cpp
+++ b/src/server/net.cpp
@@ -633,28 +633,54 @@ Server::Server(
 	const WorldSave &save)
 : serv_sock(nullptr)
 , serv_pack{ -1, nullptr, 0 }
+, serv_set(SDLNet_AllocSocketSet(1))
 , clients()
 , world(world)
 , spawn_index(world.Chunks().MakeIndex(wc.spawn, 3))
 , save(save)
 , player_model(nullptr)
 , cli(world) {
+	if (!serv_set) {
+		throw NetError("SDLNet_AllocSocketSet");
+	}
+
 	serv_sock = SDLNet_UDP_Open(conf.port);
 	if (!serv_sock) {
+		SDLNet_FreeSocketSet(serv_set);
 		throw NetError("SDLNet_UDP_Open");
 	}
 
+	if (SDLNet_UDP_AddSocket(serv_set, serv_sock) == -1) {
+		SDLNet_UDP_Close(serv_sock);
+		SDLNet_FreeSocketSet(serv_set);
+		throw NetError("SDLNet_UDP_AddSocket");
+	}
+
 	serv_pack.data = new Uint8[sizeof(Packet)];
 	serv_pack.maxlen = sizeof(Packet);
 }
 
 Server::~Server() {
+	for (ClientConnection &client : clients) {
+		client.Disconnected();
+	}
+	clients.clear();
 	world.Chunks().UnregisterIndex(spawn_index);
 	delete[] serv_pack.data;
+	SDLNet_UDP_DelSocket(serv_set, serv_sock);
 	SDLNet_UDP_Close(serv_sock);
+	SDLNet_FreeSocketSet(serv_set);
 }
 
 
+void Server::Wait(int dt) noexcept {
+	SDLNet_CheckSockets(serv_set, dt);
+}
+
+bool Server::Ready() noexcept {
+	return SDLNet_CheckSockets(serv_set, 0) > 0;
+}
+
 void Server::Handle() {
 	int result = SDLNet_UDP_Recv(serv_sock, &serv_pack);
 	while (result > 0) {
-- 
2.39.2