From d9e109e3a5d971413671fa5b285027a528b38990 Mon Sep 17 00:00:00 2001
From: Helmut Merz <helmutm@cy55.de>
Date: Sat, 3 Jun 2023 17:21:34 +0200
Subject: [PATCH] implement Context interface from standard library

---
 common/common.go | 43 +++++++++++++++++++++++++++++++++++++++----
 scopes.go        |  2 +-
 2 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/common/common.go b/common/common.go
index 60f5d99..de0ac12 100644
--- a/common/common.go
+++ b/common/common.go
@@ -1,6 +1,10 @@
 package common
 
-import "sync"
+import (
+	stdlib_context "context"
+	"sync"
+	"time"
+)
 
 type Config interface {
 	Name() string
@@ -16,6 +20,7 @@ type Services map[string]Context
 type ContextState interface{}
 
 type Context interface {
+	stdlib_context.Context
 	Config() Config
 	Parent() Context
 	Services() Services
@@ -23,8 +28,8 @@ type Context interface {
 	State() ContextState
 	WithState(ContextState) Context
 	Mailbox() chan Message
-	Done() chan struct{}
 	WaitGroup() *sync.WaitGroup
+	Stop()
 }
 
 type FctCtx = func(Context)
@@ -87,10 +92,14 @@ func (ctx *context) WaitGroup() *sync.WaitGroup {
 	return ctx.parent.WaitGroup()
 }
 
-func (ctx *context) Done() chan struct{} {
+func (ctx *context) Done() <-chan struct{} {
 	return ctx.parent.Done()
 }
 
+func (ctx *context) Stop() {
+	// ctx.Warn("Only application-level service can be stopped
+}
+
 func makeCtx(cfg Config, parent Context) *context {
 	return &context{
 		cfg:     cfg,
@@ -128,10 +137,14 @@ func (ctx *appContext) WaitGroup() *sync.WaitGroup {
 	return ctx.waitgroup
 }
 
-func (ctx *appContext) Done() chan struct{} {
+func (ctx *appContext) Done() <-chan struct{} {
 	return ctx.doneCh
 }
 
+func (ctx *appContext) Stop() {
+	close(ctx.doneCh)
+}
+
 func AppContext(cfg Config) Context {
 	ctx := &appContext{
 		context:   makeCtx(cfg, nil),
@@ -142,3 +155,25 @@ func AppContext(cfg Config) Context {
 	ctx.services[cfg.Name()] = ctx
 	return ctx
 }
+
+// implement interface context.Context from standard library
+
+func (ctx *context) Deadline() (deadline time.Time, ok bool) {
+	return time.Time{}, false
+}
+
+func (ctx *context) Err() error {
+	select {
+	case _, ok := <-ctx.Done():
+		if !ok {
+			return stdlib_context.Canceled
+		}
+	default:
+		return nil
+	}
+	return nil
+}
+
+func (ctx *context) Value(key interface{}) interface{} {
+	return nil
+}
diff --git a/scopes.go b/scopes.go
index 85f1530..5923b9e 100644
--- a/scopes.go
+++ b/scopes.go
@@ -21,7 +21,7 @@ func Start(ctx common.Context) {
 }
 
 func start(ctx common.Context) {
-	defer close(ctx.Done())
+	defer ctx.Stop()
 	for _, cfg := range ctx.Config().Children() {
 		cctx := ctx.ChildContext(cfg)
 		cfg.Starter()(cctx)