func formatMessageTarget(w io.Writer, t rpccapnp.MessageTarget) {
switch t.Which() {
case rpccapnp.MessageTarget_Which_importedCap:
fmt.Fprintf(w, "import %d", t.ImportedCap())
case rpccapnp.MessageTarget_Which_promisedAnswer:
fmt.Fprint(w, "promise ")
pa, _ := t.PromisedAnswer()
formatPromisedAnswer(w, pa)
default:
fmt.Fprintf(w, "UNKNOWN TARGET which=%v", t.Which())
}
}
func (c *Conn) routeCallMessage(result *answer, mt rpccapnp.MessageTarget, cl *capnp.Call) error {
switch mt.Which() {
case rpccapnp.MessageTarget_Which_importedCap:
id := exportID(mt.ImportedCap())
e := c.exports.get(id)
if e == nil {
return errBadTarget
}
answer := c.nestedCall(e.client, cl)
go joinAnswer(result, answer)
case rpccapnp.MessageTarget_Which_promisedAnswer:
mpromise, err := mt.PromisedAnswer()
if err != nil {
return err
}
id := answerID(mpromise.QuestionId())
if id == result.id {
// Grandfather paradox.
return errBadTarget
}
pa := c.answers.get(id)
if pa == nil {
return errBadTarget
}
mtrans, err := mpromise.Transform()
if err != nil {
return err
}
transform := promisedAnswerOpsToTransform(mtrans)
if obj, err, done := pa.peek(); done {
client := clientFromResolution(transform, obj, err)
answer := c.nestedCall(client, cl)
go joinAnswer(result, answer)
return nil
}
if err := pa.queueCall(result, transform, cl); err != nil {
return err
}
default:
panic("unreachable")
}
return nil
}