// Enqueue send a message to the topic. All subscriptions receive a copy
// of the message.
func (t *Topic) Enqueue(f *frame.Frame) {
switch t.subs.Len() {
case 0:
// no subscription, so do nothing
case 1:
// only one subscription, so can send the frame
// without copying
sub := t.subs.Front().Value.(Subscription)
sub.SendTopicFrame(f)
default:
// more than one subscription, send clone for
// all subscriptions except the last, which can
// have the frame without copying
for e := t.subs.Front(); e != nil; e = e.Next() {
sub := e.Value.(Subscription)
if e.Next() == nil {
// the last in the list, send the frame
// without copying
sub.SendTopicFrame(f)
} else {
sub.SendTopicFrame(f.Clone())
}
}
}
}
// Handle a SEND frame received from the client. Note that
// this method is called after a SEND message is received,
// but also after a transaction commit.
func (c *Conn) handleSend(f *frame.Frame) error {
// Send a receipt and remove the header
err := c.sendReceiptImmediately(f)
if err != nil {
return err
}
if tx, ok := f.Header.Contains(frame.Transaction); ok {
// the transaction header is removed from the frame
err = c.txStore.Add(tx, f)
if err != nil {
return err
}
} else {
// not in a transaction
// change from SEND to MESSAGE
f.Command = frame.MESSAGE
c.requestChannel <- Request{Op: EnqueueOp, Frame: f}
}
return nil
}