Merge pull request #1220 from ydb-platform/xcontext

added `xcontext.WithDone()` + replaced custom implementation `xcontext.ValueOnly()` to standard `context.WithoutCancel()`

Author: asmyasnikov

internal/xcontext/done.go

@@ -0,0 +1,41 @@
+package xcontext
+
+import (
+	"context"
+	"time"
+)
+
+type doneCtx <-chan struct{}
+
+func (done doneCtx) Deadline() (deadline time.Time, ok bool) {
+	return
+}
+
+func (done doneCtx) Done() <-chan struct{} {
+	return done
+}
+
+func (done doneCtx) Err() error {
+	select {
+	case <-done:
+		return context.Canceled
+	default:
+		return nil
+	}
+}
+
+func (done doneCtx) Value(key any) any {
+	return nil
+}
+
+func WithDone(parent context.Context, done <-chan struct{}) (context.Context, context.CancelFunc) {
+	ctx, cancel := context.WithCancel(parent)
+	stop := context.AfterFunc(doneCtx(done), func() {
+		cancel()
+	})
+
+	return ctx, func() {
+		stop()
+		cancel()
+	}
+}

internal/xcontext/done_test.go

@@ -0,0 +1,29 @@
+package xcontext
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestWithDone(t *testing.T) {
+	t.Run("CancelParent", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		done := make(chan struct{})
+		ctx1, _ := WithDone(ctx, done)
+		require.NoError(t, ctx1.Err())
+		cancel()
+		require.Error(t, ctx1.Err())
+	})
+	t.Run("CloseDone", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		done := make(chan struct{})
+		ctx1, cancel1 := WithDone(ctx, done)
+		require.NoError(t, ctx1.Err())
+		cancel1()
+		require.NoError(t, ctx.Err())
+		require.Error(t, ctx1.Err())
+	})
+}

internal/xcontext/without_deadline.go

@@ -2,20 +2,9 @@ package xcontext
 
 import (
 	"context"
-	"time"
 )
 
-type valueOnlyContext struct {
-	context.Context //nolint:containedctx
-}
-
-func (valueOnlyContext) Deadline() (deadline time.Time, ok bool) { return }
-
-func (valueOnlyContext) Done() <-chan struct{} { return nil }
-
-func (valueOnlyContext) Err() error { return nil }
-
 // ValueOnly helps to clear parent context from deadlines/cancels
 func ValueOnly(ctx context.Context) context.Context {
-	return valueOnlyContext{ctx}
+	return context.WithoutCancel(ctx)
 }