From 4496e975152d17d6a24b01b0a13996e0c0e22db7 Mon Sep 17 00:00:00 2001
From: Jordan Orelli <jordanorelli@gmail.com>
Date: Mon, 26 Oct 2020 23:59:30 +0000
Subject: [PATCH] stop simulation run loop when shutting down server

---
 internal/server/server.go | 28 +++++++++++++++++++---------
 internal/sim/world.go     | 12 ++++++++++++
 2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/internal/server/server.go b/internal/server/server.go
index 2c4c312..90a2ef6 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -135,35 +135,45 @@ func (s *Server) Shutdown() {
 	s.Info("starting shutdown procedure")
 
 	var wg sync.WaitGroup
-	wg.Add(2)
+	wg.Add(3)
 	go func() {
 		defer wg.Done()
-		s.Info("shutting down http server")
+
+		if err := s.world.Stop(); err != nil {
+			s.Error("error stopping the simulation: %v", err)
+		}
+	}()
+
+	go func() {
+		defer wg.Done()
+		log := s.Child("http")
+		log.Info("shutting down http server")
 		if err := s.http.Shutdown(context.Background()); err != nil {
-			s.Error("error shutting down http server: %v", err)
+			log.Error("error shutting down http server: %v", err)
 		} else {
-			s.Info("http server has shut down")
+			log.Info("http server has shut down")
 		}
 	}()
 
 	go func() {
 		defer wg.Done()
 
+		log := s.Child("sessions")
 		s.Lock()
 		if len(s.sessions) > 0 {
-			s.Info("broadcasting shutdown to %d active sessions", len(s.sessions))
+			log.Info("broadcasting shutdown to %d active sessions", len(s.sessions))
 			for id, sn := range s.sessions {
-				s.Info("sending done signal to session: %d", id)
+				log.Info("sending done signal to session: %d", id)
 				sn.done <- true
 			}
 		} else {
-			s.Info("no active sessions")
+			log.Info("no active sessions")
 		}
 		s.Unlock()
 
-		s.Info("waiting on connected sessions to shut down")
+		log.Info("waiting on connected sessions to shut down")
 		s.waitOnSessions.Wait()
-		s.Info("all sessions have shut down")
+		log.Info("all sessions have shut down")
 	}()
 	wg.Wait()
 	s.Info("shutdown procedure complete")
diff --git a/internal/sim/world.go b/internal/sim/world.go
index 8706334..723f538 100644
--- a/internal/sim/world.go
+++ b/internal/sim/world.go
@@ -10,6 +10,7 @@ import (
 type World struct {
 	*blammo.Log
 	rooms []room
+	done  chan bool
 }
 
 func NewWorld(log *blammo.Log) *World {
@@ -22,10 +23,13 @@ func NewWorld(log *blammo.Log) *World {
 				height: 10,
 			},
 		},
+		done: make(chan bool),
 	}
 }
 
 func (w *World) Run(hz int) {
+	defer w.Info("simulation has exited run loop")
+
 	period := time.Second / time.Duration(hz)
 	w.Info("starting world with a tick rate of %dhz, frame duration of %v", hz, period)
 	ticker := time.NewTicker(period)
@@ -35,10 +39,18 @@ func (w *World) Run(hz int) {
 		case <-ticker.C:
 			w.tick(time.Since(lastTick))
 			lastTick = time.Now()
+		case <-w.done:
+			return
 		}
 	}
 }
 
+func (w *World) Stop() error {
+	w.Info("stopping simulation")
+	w.done <- true
+	return nil
+}
+
 func (w *World) tick(d time.Duration) {
 	w.Info("tick. elapsed: %v", d)
 }