Node agent: a node that never composed its own takes a failed placement read as not placed; one that did keeps waiting (issue 1126)

cmd/mesh-host/nodeagent.go

@@ -896,7 +896,7 @@ func selfComposer(ctx context.Context, session *link.Session, node string, say f
 		return nil, err.Error()
 	}
 	env := composerEnv(session, node, say, hooks)
-	placed, err := selfcompose.Placed(ctx, env.Get, node, link.Backoff, say)
+	placed, err := selfcompose.Placed(ctx, env.Get, node, link.Backoff, say, composedItsOwn(ctx, env.Get, node))
 	if err != nil {
 		return nil, "its placement could not be read before the link ended: " + err.Error()
 	}
@@ -910,6 +910,24 @@ func selfComposer(ctx context.Context, session *link.Session, node string, say f
 	return selfcompose.New(env), why
 }
 
+// composedItsOwn says whether the node's own have, kept on the bus, says it composed from its placement key at its last
+// start. A have that cannot be read says yes: the safe side, a node waits and does not fall back.
+func composedItsOwn(ctx context.Context, get func(ctx context.Context, bucket, key string) ([]byte, error), node string) bool {
+	key, err := delivery.HaveNodeKey(node)
+	if err != nil {
+		return true
+	}
+	raw, err := get(ctx, delivery.HaveBucket, key)
+	if err != nil {
+		return true
+	}
+	if len(raw) == 0 {
+		return false
+	}
+	n, err := delivery.DecodeHaveNode(raw)
+	return err != nil || n.Composes == delivery.ComposesOwn
+}
+
 // composerEnv is what the node's composers read of the bus, the vault and the agent: its own composer and its answer
 // to placement candidates (selfcompose.Shadow) alike.
 func composerEnv(session *link.Session, node string, say func(string), hooks composerHooks) selfcompose.Env {