fixed up use of context to stop loops by using a select with case <-ctx.Done()

email/subscription.go

@@ -101,11 +101,13 @@ func AmDeliverSubscription(ctx context.Context, comm *database.Community, conf *
 
 	// The delivery loop; build each message and send it.  Note that sending a message puts the Message structure on
 	// the sender goroutine channel, so we have to create a new Message each time, unlike what we did in Venice.
+SendLoop:
 	for i := range recipUids {
-		err = ctx.Err()
+		select {
-		if err != nil {
+		case <-ctx.Done():
-			log.Errorf("AmDeliverSubscription: aborted on send loop iter %d with %v", i+1, err)
+			log.Errorf("AmDeliverSubscription: aborted on send loop iter %d with %v", i+1, ctx.Err())
-		}
+			break SendLoop
+		default:
 			if ci, err := database.AmGetContactInfoForUser(ctx, recipUids[i]); err == nil {
 				msg := AmNewEmailMessage(poster.Uid, ipaddr)
 				msg.SetSubject(subjectSink.GetSubject())
@@ -116,4 +118,5 @@ func AmDeliverSubscription(ctx context.Context, comm *database.Community, conf *
 				log.Warnf("AmDeliverSubscription skipped uid %d because no contact info retrieved (%v)", recipUids[i], err)
 			}
 		}
+	}
 }

htmlcheck/checker.go

@@ -801,10 +801,10 @@ func (ht *htmlCheckerImpl) finishParen() error {
 func (ht *htmlCheckerImpl) parse(str string) error {
 	i := 0
 	for i < len(str) {
-		err := ht.ctx.Err()
+		select {
-		if err != nil {
+		case <-ht.ctx.Done():
-			return err
+			return ht.ctx.Err()
-		}
+		default:
 			ch := str[i]
 			switch ht.state {
 			case stateWhitespace:
@@ -965,6 +965,7 @@ func (ht *htmlCheckerImpl) parse(str string) error {
 				log.Fatalf("invalid parser state: %d", ht.state)
 			}
 		}
+	}
 	return nil
 }