Manager paradigm change to an event-loop concurrency style, begun implementing batching in binance futures_websocket.go

services/data_service/internal/manager/helper.go

@@ -0,0 +1,100 @@
+package manager
+
+import (
+	"fmt"
+
+	"gitlab.michelsen.id/phillmichelsen/tessera/services/data_service/internal/domain"
+	"gitlab.michelsen.id/phillmichelsen/tessera/services/data_service/internal/provider"
+)
+
+// Lightweight error helper to define package-level errors inline.
+type constErr string
+
+func (e constErr) Error() string { return string(e) }
+func errorf(s string) error      { return constErr(s) }
+
+// copySet copies a set of identifiers to a new map.
+func copySet(in map[domain.Identifier]struct{}) map[domain.Identifier]struct{} {
+	out := make(map[domain.Identifier]struct{}, len(in))
+	for k := range in {
+		out[k] = struct{}{}
+	}
+	return out
+}
+
+// identifierSetDifferences computes additions and deletions from old -> next.
+func identifierSetDifferences(old map[domain.Identifier]struct{}, next []domain.Identifier) (toAdd, toDel []domain.Identifier) {
+	newSet := make(map[domain.Identifier]struct{}, len(next))
+	for _, id := range next {
+		newSet[id] = struct{}{}
+		if _, ok := old[id]; !ok {
+			toAdd = append(toAdd, id)
+		}
+	}
+	for id := range old {
+		if _, ok := newSet[id]; !ok {
+			toDel = append(toDel, id)
+		}
+	}
+	return
+}
+
+// joinErrors aggregates multiple errors.
+type joined struct{ es []error }
+
+func (j joined) Error() string {
+	switch n := len(j.es); {
+	case n == 0:
+		return ""
+	case n == 1:
+		return j.es[0].Error()
+	default:
+		s := j.es[0].Error()
+		for i := 1; i < n; i++ {
+			s += "; " + j.es[i].Error()
+		}
+		return s
+	}
+}
+
+func join(es []error) error {
+	if len(es) == 0 {
+		return nil
+	}
+	return joined{es}
+}
+
+// resolveProvider parses a raw identifier and looks up the provider.
+func (m *Manager) resolveProvider(id domain.Identifier) (provider.Provider, string, error) {
+	provName, subj, ok := id.ProviderSubject()
+	if !ok || provName == "" || subj == "" {
+		return nil, "", ErrInvalidIdentifier
+	}
+	p := m.providers[provName]
+	if p == nil {
+		return nil, "", fmt.Errorf("%w: %s", ErrUnknownProvider, provName)
+	}
+	return p, subj, nil
+}
+
+// incrementStreamRefCount increments refcount and returns true if transitioning 0->1.
+func (m *Manager) incrementStreamRefCount(id domain.Identifier) bool {
+	rc := m.streamRef[id] + 1
+	m.streamRef[id] = rc
+	return rc == 1
+}
+
+// decrementStreamRefCount decrements refcount and returns true if transitioning 1->0.
+func (m *Manager) decrementStreamRefCount(id domain.Identifier) bool {
+	rc, ok := m.streamRef[id]
+	if !ok {
+		return false
+	}
+	rc--
+	if rc <= 0 {
+		delete(m.streamRef, id)
+		return true
+	}
+	m.streamRef[id] = rc
+	return false
+}