feat: add projection layer to eventstore

pkg/es/driver/projecter/projecter.go

@@ -0,0 +1,127 @@
+package projecter
+
+import (
+	"context"
+	"strings"
+
+	"github.com/sour-is/ev/internal/lg"
+	"github.com/sour-is/ev/pkg/es"
+	"github.com/sour-is/ev/pkg/es/driver"
+	"github.com/sour-is/ev/pkg/es/event"
+)
+
+type projector struct {
+	up driver.Driver
+}
+
+func New(ctx context.Context) *projector {
+	return &projector{}
+}
+func (p *projector) Apply(e *es.EventStore) {
+	p.up = e.Driver
+	e.Driver = p
+}
+func (s *projector) Unwrap() driver.Driver {
+	return s.up
+}
+func (s *projector) Open(ctx context.Context, dsn string) (driver.Driver, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	return s.up.Open(ctx, dsn)
+}
+func (s *projector) EventLog(ctx context.Context, streamID string) (driver.EventLog, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	l, err := s.up.EventLog(ctx, streamID)
+	return &wrapper{l, s}, err
+}
+
+type wrapper struct {
+	up        driver.EventLog
+	projector *projector
+}
+
+var _ driver.EventLog = (*wrapper)(nil)
+
+func (w *wrapper) Read(ctx context.Context, pos int64, count int64) (event.Events, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	return w.up.Read(ctx, pos, count)
+}
+func (w *wrapper) Append(ctx context.Context, events event.Events, version uint64) (uint64, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	i, err := w.up.Append(ctx, events, version)
+	if err != nil {
+		return i, err
+	}
+
+	{
+		ctx, span := lg.Fork(ctx)
+
+		go func() {
+			defer span.End()
+
+			var pevents []event.Event
+
+			for i := range events {
+				e := events[i]
+				eventType := event.TypeOf(e)
+				streamID := e.EventMeta().StreamID
+				streamPos := e.EventMeta().Position
+
+				e1 := event.NewPtr(streamID, streamPos)
+				event.SetStreamID("$all", e1)
+
+				e2 := event.NewPtr(streamID, streamPos)
+				event.SetStreamID("$type-"+eventType, e2)
+
+				e3 := event.NewPtr(streamID, streamPos)
+				pkg, _, _ := strings.Cut(eventType, ".")
+				event.SetStreamID("$pkg-"+pkg, e3)
+
+				pevents = append(
+					pevents,
+					e1,
+					e2,
+					e3,
+				)
+			}
+
+			for i := range pevents {
+				e := pevents[i]
+				l, err := w.projector.up.EventLog(ctx, event.StreamID(e).StreamID())
+				if err != nil {
+					span.RecordError(err)
+					continue
+				}
+				_, err = l.Append(ctx, event.NewEvents(e), es.AppendOnly)
+				span.RecordError(err)
+			}
+		}()
+	}
+
+	return i, err
+}
+func (w *wrapper) FirstIndex(ctx context.Context) (uint64, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	return w.up.FirstIndex(ctx)
+}
+func (w *wrapper) LastIndex(ctx context.Context) (uint64, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	return w.up.LastIndex(ctx)
+}
+func (w *wrapper) LoadForUpdate(ctx context.Context, a event.Aggregate, fn func(context.Context, event.Aggregate) error) (uint64, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	return w.up.LoadForUpdate(ctx, a, fn)
+}