A state entry may say key-ttl and its bucket allows a time to live per key (issue 1154)

internal/catalogue/state.go

@@ -36,6 +36,9 @@ type StateDeclaration struct {
 	// PerMachine says the state is keyed by machine: each machine's instance writes the key named for
 	// its machine and no other, and the bus grants it that key alone (novox/hq ADR 0260).
 	PerMachine bool `json:"per-machine,omitempty"`
+	// KeyTTL says each key of the bucket lives the time its writer gives it, and the server writes a delete marker
+	// when it ends (novox/hq ADR 0433 §1): the bucket is made with the server's time to live per message.
+	KeyTTL bool `json:"key-ttl,omitempty"`
 }
 
 // UnmarshalJSON reads a bucket as its bare name, or as {name, history, ttl-seconds}.
@@ -49,7 +52,7 @@ func (s *StateDeclaration) UnmarshalJSON(raw []byte) error {
 	dec := json.NewDecoder(bytes.NewReader(trimmed))
 	dec.DisallowUnknownFields()
 	if err := dec.Decode(&full); err != nil {
-		return fmt.Errorf("a state is either a name or {name, history, ttl-seconds, per-machine}: %w", typedUnknown(err))
+		return fmt.Errorf("a state is either a name or {name, history, ttl-seconds, per-machine, key-ttl}: %w", typedUnknown(err))
 	}
 	*s = StateDeclaration(full)
 	return nil
@@ -57,7 +60,7 @@ func (s *StateDeclaration) UnmarshalJSON(raw []byte) error {
 
 // MarshalJSON writes back the short form when there is nothing else to say.
 func (s StateDeclaration) MarshalJSON() ([]byte, error) {
-	if s.History == 0 && s.TTLSeconds == 0 && !s.PerMachine {
+	if s.History == 0 && s.TTLSeconds == 0 && !s.PerMachine && !s.KeyTTL {
 		return json.Marshal(s.Name)
 	}
 	type plain StateDeclaration

internal/catalogue/state_test.go

@@ -39,7 +39,7 @@ func TestAStateNameIsLocalAndOneToken(t *testing.T) {
 		{`{"module":"a.b","version":"1","state":["s"]}`, `no dot`},
 		{`{"module":"a","version":"1","reads":["bindings"]}`, `a read is <module>.<name>`},
 		{`{"module":"a","version":"1","reads":["a.s"]}`, `which is its own state`},
-		{`{"module":"a","version":"1","state":[{"name":"s","shared":true}]}`, `{name, history, ttl-seconds, per-machine}`},
+		{`{"module":"a","version":"1","state":[{"name":"s","shared":true}]}`, `{name, history, ttl-seconds, per-machine, key-ttl}`},
 	} {
 		_, err := ParseManifest([]byte(c.manifest))
 		if err == nil {
@@ -107,3 +107,19 @@ func TestTheCataloguePassNamesAReadItsOwnerDoesNotKeep(t *testing.T) {
 		t.Fatalf("the catalogue pass said %v", problems)
 	}
 }
+
+// 1154/AC1: a state entry may say key-ttl; it is read, written back, and a bare name or an entry without it reads as before.
+func TestAStateMayHaveKeysThatExpireOneByOne(t *testing.T) {
+	m, err := ParseManifest([]byte(`{"module":"mesh-delivery-watchman","version":"1",` +
+		`"state":[{"name":"pulse","key-ttl":true},"stuck",{"name":"seen","history":5}]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !m.State[0].KeyTTL || m.State[1].KeyTTL || m.State[2].KeyTTL {
+		t.Fatalf("key-ttl not read as said: %+v", m.State)
+	}
+	out, _ := json.Marshal(m.State)
+	if string(out) != `[{"name":"pulse","key-ttl":true},"stuck",{"name":"seen","history":5}]` {
+		t.Fatalf("written back as %s", out)
+	}
+}