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Ask an acknowledgement apart from an approval, change every kept ask by compare-and-set, and rehearse rather than drill (hq ADR 0259, review M1/L2/L3/L7)

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- M1: a condition offering both kinds of answer is asked twice: its authorising answers about the
  condition, its acknowledging ones (Silence) apart, so an answer from a channel that only acknowledges
  never ends an approval.
- L2: the asked store creates once and changes only over the revision it read, deciding again on what it
  reads; a stale cancel no longer writes over an act.
- L3: every ask is kept before it is published, one whose publishing failed is marked unsent and asked
  again, and a cancel is kept before it is said. The terminal's test question is now `rehearse`, so it is
  not called what the glossary calls a drill; its two answers are both approve-level.
- L7: two deliveries of one warrant to two controllers at once act exactly once, on a real bus.
- Re-vendored onto mesh-sdk 76902998 (canonical digests): an option binds an asks.Act with each argument
  as arg.<name>.
- The lab's bus fixture composes verified-sender only where the lab says its machine is root-free
  (MESH_LAB_ASKS_ROOT_FREE=true).
This commit is contained in:
jschoubben
2026-10-09 16:22:34 +02:00
parent ad406e81b8
commit 799eec0a5a
14 changed files with 736 additions and 321 deletions
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cmd/mesh-controller/asker_wire.go
+42 -37
View File
@@ -57,7 +57,8 @@ func (b busAsked) Get(ctx context.Context, id string) (*asked, error) {
return &r, json.Unmarshal(e.Value(), &r)
}
func (b busAsked) Put(ctx context.Context, r asked) error {
// Create keeps a new ask under its id, and only where none is kept: never over another.
func (b busAsked) Create(ctx context.Context, r asked) error {
kv, err := b.kv(ctx)
if err != nil {
return err
@@ -66,10 +67,49 @@ func (b busAsked) Put(ctx context.Context, r asked) error {
if err != nil {
return err
}
_, err = kv.Put(ctx, r.ID, body)
_, err = kv.Create(ctx, r.ID, body)
return err
}
// Change applies change to the ask kept under id by compare-and-set on its key's revision (the review of
// 2026-10-09, L2): read, changed, and written only over the revision read; when another write came between,
// read again and asked again, at most askChangeTries times. change says whether to write at all.
func (b busAsked) Change(ctx context.Context, id string, change func(*asked) bool) (bool, error) {
kv, err := b.kv(ctx)
if err != nil {
return false, err
}
for try := 0; try < askChangeTries; try++ {
e, err := kv.Get(ctx, id)
if errors.Is(err, jetstream.ErrKeyNotFound) {
return false, nil
}
if err != nil {
return false, err
}
var r asked
if err := json.Unmarshal(e.Value(), &r); err != nil {
return false, err
}
if !change(&r) {
return false, nil
}
body, err := json.Marshal(r)
if err != nil {
return false, err
}
if _, err := kv.Update(ctx, id, body, e.Revision()); err != nil {
var api *jetstream.APIError
if errors.Is(err, jetstream.ErrKeyExists) || (errors.As(err, &api) && api.ErrorCode == jetstream.JSErrCodeStreamWrongLastSequence) {
continue
}
return false, err
}
return true, nil
}
return false, fmt.Errorf("the ask %s changed under every one of %d tries", id, askChangeTries)
}
func (b busAsked) All(ctx context.Context) ([]asked, error) {
kv, err := b.kv(ctx)
if err != nil {
@@ -94,41 +134,6 @@ func (b busAsked) All(ctx context.Context) ([]asked, error) {
return out, nil
}
// Claim marks an open ask acting, by compare-and-set on its key's revision: only the write that stands acts.
func (b busAsked) Claim(ctx context.Context, id string, w asks.Warrant) (bool, error) {
kv, err := b.kv(ctx)
if err != nil {
return false, err
}
e, err := kv.Get(ctx, id)
if errors.Is(err, jetstream.ErrKeyNotFound) {
return false, nil
}
if err != nil {
return false, err
}
var r asked
if err := json.Unmarshal(e.Value(), &r); err != nil {
return false, err
}
if r.State != askOpen || r.Acted != "" {
return false, nil
}
r.State, r.Warrant, r.Acted = string(asks.OutcomeChosen), &w, "acting"
body, err := json.Marshal(r)
if err != nil {
return false, err
}
if _, err := kv.Update(ctx, id, body, e.Revision()); err != nil {
var api *jetstream.APIError
if errors.Is(err, jetstream.ErrKeyExists) || (errors.As(err, &api) && api.ErrorCode == jetstream.JSErrCodeStreamWrongLastSequence) {
return false, nil
}
return false, err
}
return true, nil
}
// callAction performs an action's verb as the controller, through the grant that names it.
func callAction(conn *nats.Conn) func(ctx context.Context, a conditions.Action, args map[string]string) error {
return func(ctx context.Context, a conditions.Action, args map[string]string) error {