perf: index routing snapshots and quota usage

internal/registry/registry.go

@@ -227,6 +227,20 @@ func (TCPReachability) Reachable(address string, timeout time.Duration) bool {
 	return true
 }
 func (r Registry) Candidates(project string, check Reachability, timeout time.Duration) ([]Herdr, error) {
+	return r.candidates(project, func(h Herdr) bool {
+		address := r.Endpoint(h)
+		return check == nil || check.Reachable(address, timeout)
+	})
+}
+
+// CandidatesWithHealth filters candidates using a health snapshot gathered by
+// the router. Keeping probe execution outside this method lets a scheduling
+// pass probe each herdr once, in parallel, instead of once per queued task.
+func (r Registry) CandidatesWithHealth(project string, healthy map[string]bool) ([]Herdr, error) {
+	return r.candidates(project, func(h Herdr) bool { return healthy[h.ID] })
+}
+
+func (r Registry) candidates(project string, include func(Herdr) bool) ([]Herdr, error) {
 	p, ok := r.projects[project]
 	if !ok {
 		return nil, ErrUnknownProject
@@ -237,20 +251,25 @@ func (r Registry) Candidates(project string, check Reachability, timeout time.Du
 	}
 	out := []Herdr{}
 	for _, h := range r.herdrs {
-		if !allowed[h.MachineID] {
+		if !allowed[h.MachineID] || !include(h) {
 			continue
 		}
-		addr := h.Address
-		if addr == "" {
-			addr = r.machines[h.MachineID].Address
-			if host, _, err := net.SplitHostPort(addr); err == nil {
-				addr = net.JoinHostPort(host, defaultHerdrPort)
-			}
-		}
-		if check == nil || check.Reachable(addr, timeout) {
-			out = append(out, h)
-		}
+		out = append(out, h)
 	}
 	sort.Slice(out, func(i, j int) bool { return out[i].ID < out[j].ID })
 	return out, nil
 }
+
+// Endpoint resolves the herdr-specific address or its machine's default
+// herdr endpoint. It is exposed so health checks can be batched independently
+// from project routing.
+func (r Registry) Endpoint(h Herdr) string {
+	if h.Address != "" {
+		return h.Address
+	}
+	address := r.machines[h.MachineID].Address
+	if host, _, err := net.SplitHostPort(address); err == nil {
+		return net.JoinHostPort(host, defaultHerdrPort)
+	}
+	return address
+}