[refactoring] Close history preserver file automatically on exit

Author: g3force

internal/app/controller/controller.go

@@ -71,6 +71,7 @@ func (c *GameController) Run() {
 			c.Engine.UiProtocol = c.Engine.History[len(c.Engine.History)-1].UiProtocol
 		}
 	}
+	c.historyPreserver.CloseOnExit()
 
 	c.ApiServer.PublishState(*c.Engine.State, c.Engine.EngineState)
 	c.ApiServer.PublishUiProtocol(c.Engine.UiProtocol)
@@ -99,7 +100,6 @@ func (c *GameController) setupTimeProvider() {
 
 // mainLoop updates several states every full second and publishes the new state
 func (c *GameController) mainLoop() {
-	defer c.historyPreserver.Close()
 	for {
 		time.Sleep(time.Millisecond * 10)
 

internal/app/controller/engineHistory.go

@@ -6,6 +6,8 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"os/signal"
+	"syscall"
 )
 
 const maxHistorySize = 10
@@ -32,6 +34,18 @@ func (r *HistoryPreserver) Open() error {
 	return nil
 }
 
+// CloseOnExit makes sure to close the file when program exists
+func (r *HistoryPreserver) CloseOnExit() {
+	var gracefulStop = make(chan os.Signal)
+	signal.Notify(gracefulStop, syscall.SIGTERM)
+	signal.Notify(gracefulStop, syscall.SIGINT)
+	go func() {
+		<-gracefulStop
+		r.Close()
+		os.Exit(0)
+	}()
+}
+
 // Close closes the history file
 func (r *HistoryPreserver) Close() {
 	if r.historyFile == nil {