private/context2: add WithoutCancellation

Change-Id: I38557c16f41b8983886f256353cc6afb7634d9e6

private/context2/nocancel.go

@@ -0,0 +1,49 @@
+// Copyright (C) 2020 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+// Package context2 contains utilities for contexts.
+package context2
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+// WithoutCancellation returns a context that does not propagate Done message
+// down to children. However, Values are propagated.
+func WithoutCancellation(ctx context.Context) context.Context {
+	return noCancelContext{ctx}
+}
+
+type noCancelContext struct {
+	ctx context.Context
+}
+
+// Deadline returns the time when work done on behalf of this context
+// should be canceled.
+func (noCancelContext) Deadline() (deadline time.Time, ok bool) {
+	return time.Time{}, false
+}
+
+// Done returns empty channel.
+func (noCancelContext) Done() <-chan struct{} {
+	return nil
+}
+
+// Err always returns nil
+func (noCancelContext) Err() error {
+	return nil
+}
+
+// String returns string.
+func (ctx noCancelContext) String() string {
+	return fmt.Sprintf("no cancel (%s)", ctx.ctx)
+}
+
+// Value returns the value associated with this context for key, or nil
+// if no value is associated with key. Successive calls to Value with
+// the same key returns the same result.
+func (ctx noCancelContext) Value(key interface{}) interface{} {
+	return ctx.ctx.Value(key)
+}

private/context2/nocancel_test.go

@@ -0,0 +1,26 @@
+// Copyright (C) 2020 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+package context2_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"storj.io/common/testcontext"
+	"storj.io/storj/private/context2"
+)
+
+func TestWithoutCancellation(t *testing.T) {
+	ctx := testcontext.New(t)
+	defer ctx.Cleanup()
+
+	parent, cancel := context.WithCancel(ctx)
+	cancel()
+
+	without := context2.WithoutCancellation(parent)
+	require.Equal(t, error(nil), without.Err())
+	require.Equal(t, (<-chan struct{})(nil), without.Done())
+}

storagenode/piecestore/endpoint.go

@@ -25,6 +25,7 @@ import (
 	"storj.io/common/signing"
 	"storj.io/common/storj"
 	"storj.io/common/sync2"
+	"storj.io/storj/private/context2"
 	"storj.io/storj/storagenode/bandwidth"
 	"storj.io/storj/storagenode/monitor"
 	"storj.io/storj/storagenode/orders"
@@ -707,9 +708,8 @@ func (endpoint *Endpoint) doDownload(stream downloadStream) (err error) {
 
 // saveOrder saves the order with all necessary information. It assumes it has been already verified.
 func (endpoint *Endpoint) saveOrder(ctx context.Context, limit *pb.OrderLimit, order *pb.Order) {
-	// intentionally using background context to ensure that we always save the order,
+	// We always want to save order to the database to be able to settle.
-	// even when the client cancels the request.
+	ctx = context2.WithoutCancellation(ctx)
-	alwaysctx := context.Background()
 
 	var err error
 	defer mon.Task()(&ctx)(&err)
@@ -718,14 +718,14 @@ func (endpoint *Endpoint) saveOrder(ctx context.Context, limit *pb.OrderLimit, o
 	if order == nil || order.Amount <= 0 {
 		return
 	}
-	err = endpoint.orders.Enqueue(alwaysctx, &orders.Info{
+	err = endpoint.orders.Enqueue(ctx, &orders.Info{
 		Limit: limit,
 		Order: order,
 	})
 	if err != nil {
 		endpoint.log.Error("failed to add order", zap.Error(err))
 	} else {
-		err = endpoint.usage.Add(alwaysctx, limit.SatelliteId, limit.Action, order.Amount, time.Now())
+		err = endpoint.usage.Add(ctx, limit.SatelliteId, limit.Action, order.Amount, time.Now())
 		if err != nil {
 			endpoint.log.Error("failed to add bandwidth usage", zap.Error(err))
 		}