From 449679665b828c80480d16c96e600007a5f7b0bf Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 8 Jun 2019 01:43:07 +0900
Subject: [PATCH] thread: Use standard context.Context

---
 internal/thread/thread.go    |  9 +++++----
 internal/uidriver/glfw/ui.go | 22 +++++++++++-----------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/internal/thread/thread.go b/internal/thread/thread.go
index edc9ca466..c93e518f7 100644
--- a/internal/thread/thread.go
+++ b/internal/thread/thread.go
@@ -15,6 +15,7 @@
 package thread
 
 import (
+	"context"
 	"sync/atomic"
 )
 
@@ -36,17 +37,17 @@ func New() *Thread {
 // Loop starts the thread loop.
 //
 // Loop must be called on the thread.
-func (t *Thread) Loop(ch <-chan error) error {
+func (t *Thread) Loop(context context.Context) {
 	atomic.StoreInt32(&t.started, 1)
 	defer atomic.StoreInt32(&t.started, 0)
 
+loop:
 	for {
 		select {
 		case f := <-t.funcs:
 			f()
-		case err := <-ch:
-			// ch returns a value not only when an error occur but also it is closed.
-			return err
+		case <-context.Done():
+			break loop
 		}
 	}
 }
diff --git a/internal/uidriver/glfw/ui.go b/internal/uidriver/glfw/ui.go
index 7d44b407c..91fe7fc19 100644
--- a/internal/uidriver/glfw/ui.go
+++ b/internal/uidriver/glfw/ui.go
@@ -20,6 +20,7 @@
 package glfw
 
 import (
+	"context"
 	"image"
 	"math"
 	"runtime"
@@ -171,11 +172,9 @@ func getCachedMonitor(wx, wy int) (*cachedMonitor, bool) {
 	return nil, false
 }
 
-func (u *UserInterface) mainThreadLoop(ch <-chan error) error {
+func (u *UserInterface) mainThreadLoop(context context.Context) error {
 	u.setRunning(true)
-	if err := u.t.Loop(ch); err != nil {
-		return err
-	}
+	u.t.Loop(context)
 	u.setRunning(false)
 	return nil
 }
@@ -561,22 +560,23 @@ func init() {
 	runtime.LockOSThread()
 }
 
-func (u *UserInterface) Run(width, height int, scale float64, title string, context driver.UIContext, graphics driver.Graphics) error {
+func (u *UserInterface) Run(width, height int, scale float64, title string, uicontext driver.UIContext, graphics driver.Graphics) error {
 	// Initialize the main thread first so the thread is available at u.run (#809).
 	u.t = thread.New()
 
-	ch := make(chan error)
+	ctx, cancel := context.WithCancel(context.Background())
+
+	ch := make(chan error, 1)
 	go func() {
+		defer cancel()
 		defer close(ch)
-		if err := u.run(width, height, scale, title, context, graphics); err != nil {
+		if err := u.run(width, height, scale, title, uicontext, graphics); err != nil {
 			ch <- err
 		}
 	}()
 
-	if err := u.mainThreadLoop(ch); err != nil {
-		return err
-	}
-	return nil
+	u.mainThreadLoop(ctx)
+	return <-ch
 }
 
 func (u *UserInterface) RunWithoutMainLoop(width, height int, scale float64, title string, context driver.UIContext, graphics driver.Graphics) <-chan error {