chore: add more trace attrs, add truncate

pkg/es/driver/disk-store/disk-store.go

@@ -6,11 +6,13 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"hash/fnv"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/tidwall/wal"
+	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric/instrument/syncint64"
 	"go.uber.org/multierr"
 
@@ -43,7 +45,7 @@ const AppendOnly = es.AppendOnly
 const AllEvents = es.AllEvents
 
 func Init(ctx context.Context) error {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	d := &diskStore{}
@@ -74,6 +76,10 @@ func (d *diskStore) Open(ctx context.Context, dsn string) (driver.Driver, error)
 	_, span := lg.Span(ctx)
 	defer span.End()
 
+	span.SetAttributes(
+		attribute.String("args.dsn", dsn),
+	)
+
 	scheme, path, ok := strings.Cut(dsn, ":")
 	if !ok {
 		return nil, fmt.Errorf("expected scheme")
@@ -91,11 +97,11 @@ func (d *diskStore) Open(ctx context.Context, dsn string) (driver.Driver, error)
 		}
 	}
 	c, err := cache.NewWithEvict(CachSize, func(ctx context.Context, s string, l *lockedWal) {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		l.Modify(ctx, func(ctx context.Context, w *wal.Log) error {
-			_, span := lg.Span(ctx)
+			ctx, span := lg.Span(ctx)
 			defer span.End()
 
 			d.m_disk_evict.Add(ctx, 1)
@@ -123,13 +129,18 @@ func (d *diskStore) Open(ctx context.Context, dsn string) (driver.Driver, error)
 	}, nil
 }
 func (d *diskStore) EventLog(ctx context.Context, streamID string) (driver.EventLog, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	span.SetAttributes(
+		attribute.String("args.streamID", streamID),
+		attribute.String("path", d.path),
+	)
+
 	el := &eventLog{streamID: streamID, diskStore: d}
 
 	return el, d.openlogs.Modify(ctx, func(ctx context.Context, openlogs *openlogs) error {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		if events, ok := openlogs.logs.Get(streamID); ok {
@@ -139,7 +150,16 @@ func (d *diskStore) EventLog(ctx context.Context, streamID string) (driver.Event
 
 		d.m_disk_open.Add(ctx, 1)
 
-		l, err := wal.Open(filepath.Join(d.path, streamID), wal.DefaultOptions)
+		// migrate streams into dir friendly subdirs
+		hashPart := mkDirName(streamID)
+		oldPath := filepath.Join(d.path, streamID)
+		newPath := filepath.Join(d.path, hashPart, streamID)
+		if _, err := os.Stat(oldPath); !os.IsNotExist(err) {
+			os.MkdirAll(filepath.Join(d.path, hashPart), 0700)
+			os.Rename(oldPath, newPath)
+		}
+
+		l, err := wal.Open(newPath, wal.DefaultOptions)
 		if err != nil {
 			span.RecordError(err)
 			return err
@@ -160,14 +180,22 @@ type eventLog struct {
 var _ driver.EventLog = (*eventLog)(nil)
 
 func (e *eventLog) Append(ctx context.Context, events event.Events, version uint64) (uint64, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	span.SetAttributes(
+		attribute.Int("args.events", len(events)),
+		attribute.Int64("args.version", int64(version)),
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+
+	)
+
 	event.SetStreamID(e.streamID, events...)
 
 	var count uint64
 	err := e.events.Modify(ctx, func(ctx context.Context, l *wal.Log) error {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		last, err := l.LastIndex()
@@ -210,13 +238,19 @@ func (e *eventLog) Append(ctx context.Context, events event.Events, version uint
 	return count, err
 }
 func (e *eventLog) Read(ctx context.Context, after, count int64) (event.Events, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
+	span.SetAttributes(
+		attribute.Int64("args.after", after),
+		attribute.Int64("args.count", count),
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+	)
 
 	var events event.Events
 
 	err := e.events.Modify(ctx, func(ctx context.Context, stream *wal.Log) error {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		first, err := stream.FirstIndex()
@@ -239,9 +273,17 @@ func (e *eventLog) Read(ctx context.Context, after, count int64) (event.Events,
 			return nil
 		}
 
+		span.SetAttributes(
+			attribute.Int64("first", int64(first)),
+			attribute.Int64("last", int64(last)),
+			attribute.Int64("start", int64(start)),
+			attribute.Int64("count", int64(count)),
+			attribute.Int64("after", int64(after)),
+
+		)
+
 		events = make([]event.Event, math.Abs(count))
 		for i := range events {
-			span.AddEvent(fmt.Sprintf("read event %d of %d", i, len(events)))
 
 			// ---
 			events[i], err = readStream(ctx, stream, start)
@@ -250,6 +292,7 @@ func (e *eventLog) Read(ctx context.Context, after, count int64) (event.Events,
 				return err
 			}
 			// ---
+			span.AddEvent(fmt.Sprintf("read event %d of %d - %d", i, len(events), events[i].EventMeta().ActualPosition))
 
 			if count > 0 {
 				start += 1
@@ -274,9 +317,20 @@ func (e *eventLog) Read(ctx context.Context, after, count int64) (event.Events,
 	return events, nil
 }
 func (e *eventLog) ReadN(ctx context.Context, index ...uint64) (event.Events, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	lis := make([]int64, len(index))
+	for i := range index {
+		lis[i]=int64(index[i])
+	}
+
+	span.SetAttributes(
+		attribute.Int64Slice("args.index", lis),
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+	)
+
 	var events event.Events
 	err := e.events.Modify(ctx, func(ctx context.Context, stream *wal.Log) error {
 		var err error
@@ -289,9 +343,14 @@ func (e *eventLog) ReadN(ctx context.Context, index ...uint64) (event.Events, er
 	return events, err
 }
 func (e *eventLog) FirstIndex(ctx context.Context) (uint64, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 	
+	span.SetAttributes(
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+	)
+
 	var idx uint64
 	var err error
 
@@ -303,9 +362,14 @@ func (e *eventLog) FirstIndex(ctx context.Context) (uint64, error) {
 	return idx, err
 }
 func (e *eventLog) LastIndex(ctx context.Context) (uint64, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	span.SetAttributes(
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+	)
+
 	var idx uint64
 	var err error
 
@@ -316,13 +380,34 @@ func (e *eventLog) LastIndex(ctx context.Context) (uint64, error) {
 
 	return idx, err
 }
-func (e *eventLog) LoadForUpdate(ctx context.Context, a event.Aggregate, fn func(context.Context, event.Aggregate) error) (uint64, error) {
+func (e *eventLog) Truncate(ctx context.Context, index int64) error {
-	panic("not implemented")
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+	
+	span.SetAttributes(
+		attribute.Int64("args.index", index),
+		attribute.String("streamID", e.streamID),
+		attribute.String("path", e.diskStore.path),
+	)
+
+	if index == 0 {
+		return nil
+	}
+	return e.events.Modify(ctx, func(ctx context.Context, events *wal.Log) error {
+		if index < 0 {
+			return events.TruncateBack(uint64(-index))
+		}
+		return events.TruncateFront(uint64(index))
+	})
 }
 func readStream(ctx context.Context, stream *wal.Log, index uint64) (event.Event, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	span.SetAttributes(
+		attribute.Int64("args.index", int64(index)),
+	)
+
 	var b []byte
 	var err error
 	b, err = stream.Read(index)
@@ -342,9 +427,18 @@ func readStream(ctx context.Context, stream *wal.Log, index uint64) (event.Event
 	return e, err
 }
 func readStreamN(ctx context.Context, stream *wal.Log, index ...uint64) (event.Events, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
+	lis := make([]int64, len(index))
+	for i := range index {
+		lis[i]=int64(index[i])
+	}
+
+	span.SetAttributes(
+		attribute.Int64Slice("args.index", lis),
+	)
+
 	var b []byte
 	var err error
 	events := make(event.Events, len(index))
@@ -366,3 +460,8 @@ func readStreamN(ctx context.Context, stream *wal.Log, index ...uint64) (event.E
 	}
 	return events, err
 }
+func mkDirName(name string) string {
+	h := fnv.New32a()
+	fmt.Fprint(h, name)
+	return fmt.Sprintf("%x/%x/%x", h.Sum32()>>24&0xff, h.Sum32()>>16&0xff, h.Sum32()&0xffff)
+}

pkg/es/driver/driver.go

@@ -19,6 +19,10 @@ type EventLog interface {
 	FirstIndex(context.Context) (uint64, error)
 	LastIndex(context.Context) (uint64, error)
 }
+type EventLogWithTruncate interface {
+	Truncate(context.Context, int64) error
+}
+
 type EventLogWithUpdate interface {
 	LoadForUpdate(context.Context, event.Aggregate, func(context.Context, event.Aggregate) error) (uint64, error)
 }

pkg/es/driver/mem-store/mem-store.go

@@ -77,7 +77,7 @@ func (m *eventLog) Append(ctx context.Context, events event.Events, version uint
 	event.SetStreamID(m.streamID, events...)
 
 	return uint64(len(events)), m.events.Modify(ctx, func(ctx context.Context, stream *event.Events) error {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		span.AddEvent(fmt.Sprintf(" %s %d", m.streamID, len(*stream)))
@@ -113,7 +113,7 @@ func (m *eventLog) Append(ctx context.Context, events event.Events, version uint
 
 // ReadOne implements readone
 func (m *eventLog) ReadN(ctx context.Context, index ...uint64) (event.Events, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	var events event.Events
@@ -136,7 +136,7 @@ func (m *eventLog) Read(ctx context.Context, after int64, count int64) (event.Ev
 	var events event.Events
 
 	err := m.events.Modify(ctx, func(ctx context.Context, stream *event.Events) error {
-		_, span := lg.Span(ctx)
+		ctx, span := lg.Span(ctx)
 		defer span.End()
 
 		span.AddEvent(fmt.Sprintf("%s %d", m.streamID, len(*stream)))
@@ -188,7 +188,7 @@ func (m *eventLog) Read(ctx context.Context, after int64, count int64) (event.Ev
 
 // FirstIndex for the streamID
 func (m *eventLog) FirstIndex(ctx context.Context) (uint64, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	events, err := m.events.Copy(ctx)
@@ -197,7 +197,7 @@ func (m *eventLog) FirstIndex(ctx context.Context) (uint64, error) {
 
 // LastIndex for the streamID
 func (m *eventLog) LastIndex(ctx context.Context) (uint64, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	events, err := m.events.Copy(ctx)
@@ -209,7 +209,7 @@ func (m *eventLog) LoadForUpdate(ctx context.Context, a event.Aggregate, fn func
 }
 
 func readStream(ctx context.Context, stream *event.Events, index uint64) (event.Event, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	var b []byte
@@ -219,14 +219,14 @@ func readStream(ctx context.Context, stream *event.Events, index uint64) (event.
 	if err != nil {
 		return nil, err
 	}
-	e, err = event.UnmarshalBinary(ctx, b, e.EventMeta().Position)
+	e, err = event.UnmarshalBinary(ctx, b, e.EventMeta().ActualPosition)
 	if err != nil {
 		return nil, err
 	}
 	return e, err
 }
 func readStreamN(ctx context.Context, stream *event.Events, index ...uint64) (event.Events, error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	var b []byte

pkg/es/driver/projecter/projecter.go

@@ -47,6 +47,9 @@ type wrapper struct {
 
 var _ driver.EventLog = (*wrapper)(nil)
 
+func (r *wrapper) Unwrap() driver.EventLog {
+	return r.up
+}
 func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
@@ -114,19 +117,7 @@ func (w *wrapper) LastIndex(ctx context.Context) (uint64, error) {
 
 	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()
 
-	up := w.up
-	for up != nil {
-		if up, ok := up.(driver.EventLogWithUpdate); ok {
-			return up.LoadForUpdate(ctx, a, fn)
-		}
-		up = es.Unwrap(up)
-	}
-	return 0, es.ErrNoDriver
-}
 
 func DefaultProjection(e event.Event) []event.Event {
 	m := e.EventMeta()

pkg/es/driver/resolve-links/resolve-links.go

@@ -2,6 +2,7 @@ package resolvelinks
 
 import (
 	"context"
+	"errors"
 
 	"github.com/sour-is/ev/internal/lg"
 	"github.com/sour-is/ev/pkg/es"
@@ -43,6 +44,9 @@ type wrapper struct {
 	resolvelinks *resolvelinks
 }
 
+func (r *wrapper) Unwrap() driver.EventLog {
+	return r.up
+}
 func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
@@ -60,11 +64,18 @@ func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Eve
 				return nil, err
 			}
 			lis, err := d.ReadN(ctx, e.Pos)
-			if err != nil {
+			if err != nil && !errors.Is(err, es.ErrNotFound) {
 				return nil, err
 			}
 
-			events[i] = lis.First()
+			if ne := lis.First(); ne != event.NilEvent {
+				meta := ne.EventMeta()
+				actual := e.EventMeta()
+				meta.ActualPosition = actual.Position
+				meta.ActualStreamID = actual.ActualStreamID
+				ne.SetEventMeta(meta)
+				events[i] = ne
+			}
 		}
 	}
 
@@ -92,7 +103,14 @@ func (w *wrapper) ReadN(ctx context.Context, index ...uint64) (event.Events, err
 				return nil, err
 			}
 
-			events[i] = lis.First()
+			ne := lis.First()
+			meta := ne.EventMeta()
+			actual := e.EventMeta()
+			meta.ActualPosition = actual.Position
+			meta.ActualStreamID = actual.ActualStreamID
+			ne.SetEventMeta(meta)
+
+			events[i] = ne
 		}
 	}
 

pkg/es/driver/streamer/streamer.go

@@ -5,13 +5,14 @@ import (
 	"context"
 	"fmt"
 
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+
 	"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"
 	"github.com/sour-is/ev/pkg/locker"
-	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/trace"
 )
 
 type state struct {
@@ -89,10 +90,16 @@ func (s *streamer) Send(ctx context.Context, streamID string, events event.Event
 
 		for _, sub := range state.subscribers[streamID] {
 			err := sub.position.Modify(ctx, func(ctx context.Context, position *position) error {
-				_, span := lg.Span(ctx)
+				ctx, span := lg.Span(ctx)
 				defer span.End()
+				span.SetAttributes(
+					attribute.String("streamID", streamID),
+					attribute.Int64("actualPosition", int64(events.Last().EventMeta().ActualPosition)),
+					attribute.String("actualStreamID", events.Last().EventMeta().ActualStreamID),
+					attribute.Int64("position", int64(events.Last().EventMeta().Position)),
+				)
 
-				position.size = int64(events.Last().EventMeta().Position - uint64(position.idx))
+				position.size = int64(events.Last().EventMeta().ActualPosition - uint64(position.idx))
 
 				if position.wait != nil {
 					close(position.wait)
@@ -142,6 +149,9 @@ type wrapper struct {
 
 var _ driver.EventLog = (*wrapper)(nil)
 
+func (r *wrapper) Unwrap() driver.EventLog {
+	return r.up
+}
 func (w *wrapper) Read(ctx context.Context, after int64, count int64) (event.Events, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
@@ -185,19 +195,6 @@ func (w *wrapper) LastIndex(ctx context.Context) (uint64, error) {
 
 	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()
-
-	up := w.up
-	for up != nil {
-		if up, ok := up.(driver.EventLogWithUpdate); ok {
-			return up.LoadForUpdate(ctx, a, fn)
-		}
-		up = es.Unwrap(up)
-	}
-	return 0, es.ErrNoDriver
-}
 
 type position struct {
 	size int64
@@ -280,8 +277,15 @@ func (s *subscription) Events(ctx context.Context) (event.Events, error) {
 		}
 		position.size = int64(len(events))
 		if len(events) > 0 {
-			position.idx = int64(events.First().EventMeta().Position - 1)
+			position.idx = int64(events.First().EventMeta().ActualPosition - 1)
 		}
+		span.SetAttributes(
+			attribute.Int64("position.idx", position.idx),
+			attribute.Int64("position.size", position.size),
+			attribute.Int64("meta.ActualPosition", int64(events.First().EventMeta().ActualPosition)),
+			attribute.Int64("meta.Position", int64(events.First().EventMeta().Position)),
+		)
+
 		return err
 	})
 }

pkg/es/es.go

@@ -7,13 +7,14 @@ import (
 	"fmt"
 	"strings"
 
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric/instrument/syncint64"
+	"go.uber.org/multierr"
+
 	"github.com/sour-is/ev/internal/lg"
 	"github.com/sour-is/ev/pkg/es/driver"
 	"github.com/sour-is/ev/pkg/es/event"
 	"github.com/sour-is/ev/pkg/locker"
-	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric/instrument/syncint64"
-	"go.uber.org/multierr"
 )
 
 type config struct {
@@ -194,7 +195,7 @@ func (es *EventStore) ReadN(ctx context.Context, streamID string, index ...uint6
 	defer span.End()
 
 	lis := make([]int64, len(index))
-	for i,j :=range index {
+	for i, j := range index {
 		lis[i] = int64(j)
 	}
 
@@ -231,6 +232,7 @@ func (es *EventStore) Append(ctx context.Context, streamID string, events event.
 func (es *EventStore) FirstIndex(ctx context.Context, streamID string) (uint64, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
+
 	span.SetAttributes(
 		attribute.String("ev.streamID", streamID),
 	)
@@ -244,6 +246,7 @@ func (es *EventStore) FirstIndex(ctx context.Context, streamID string) (uint64,
 func (es *EventStore) LastIndex(ctx context.Context, streamID string) (uint64, error) {
 	ctx, span := lg.Span(ctx)
 	defer span.End()
+
 	span.SetAttributes(
 		attribute.String("ev.streamID", streamID),
 	)
@@ -268,6 +271,23 @@ func (es *EventStore) EventStream() driver.EventStream {
 	}
 	return nil
 }
+func (es *EventStore) Truncate(ctx context.Context, streamID string, index int64) error {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+	
+	up, err := es.Driver.EventLog(ctx, streamID)
+	if err != nil {
+		return err
+	}
+
+	for up != nil {
+		if up, ok := up.(driver.EventLogWithTruncate); ok {
+			return up.Truncate(ctx, index)
+		}
+		up = Unwrap(up)
+	}
+	return ErrNoDriver
+}
 
 func Unwrap[T any](t T) T {
 	if unwrap, ok := any(t).(interface{ Unwrap() T }); ok {

pkg/es/es.graphqls

@@ -1,14 +1,17 @@
 
 type Meta @goModel(model: "github.com/sour-is/ev/pkg/es/event.Meta") {
     eventID: String! @goField(name: "getEventID")
-    streamID: String!
+    streamID: String! @goField(name: "ActualStreamID")
+    position: Int! @goField(name: "ActualPosition")
     created: Time!
-    position: Int!
 }
 
 extend type Query {
     events(streamID: String! paging: PageInput): Connection!
 }
+extend type Mutation {
+    truncateStream(streamID: String! index:Int!): Boolean!
+}
 extend type Subscription {
     """after == 0 start from begining, after == -1 start from end"""
     eventAdded(streamID: String! after: Int! = -1): Event
@@ -18,6 +21,9 @@ type Event implements Edge @goModel(model: "github.com/sour-is/ev/pkg/es.GQLEven
     id: ID!
 
     eventID: String!
+    streamID: String!
+    position: Int!
+
     values: Map!
     bytes: String!
     type: String!

pkg/es/event/events.go

@@ -107,6 +107,9 @@ func SetStreamID(id string, lis ...Event) {
 	for _, e := range lis {
 		meta := e.EventMeta()
 		meta.StreamID = id
+		if meta.ActualStreamID == "" {
+			meta.ActualStreamID = id
+		}
 		e.SetEventMeta(meta)
 	}
 }
@@ -122,13 +125,16 @@ func SetEventID(e Event, id ulid.ULID) {
 func SetPosition(e Event, i uint64) {
 	meta := e.EventMeta()
 	meta.Position = i
+	meta.ActualPosition = i
 	e.SetEventMeta(meta)
 }
 
 type Meta struct {
-	EventID  ulid.ULID
+	EventID        ulid.ULID
-	StreamID string
+	StreamID       string
-	Position uint64
+	Position       uint64
+	ActualStreamID string
+	ActualPosition uint64
 }
 
 func (m Meta) Created() time.Time {
@@ -146,11 +152,10 @@ func Init(ctx context.Context) error {
 	return nil
 }
 
-type nilEvent struct{}
+type nilEvent struct {
-
-func (*nilEvent) EventMeta() Meta {
-	return Meta{}
 }
+
+func (*nilEvent) EventMeta() Meta             { return Meta{} }
 func (*nilEvent) SetEventMeta(eventMeta Meta) {}
 
 var NilEvent = &nilEvent{}

pkg/es/event/reflect.go

@@ -67,7 +67,7 @@ func (u *UnknownEvent) MarshalBinary() ([]byte, error) {
 
 // Register a type container for Unmarshalling values into. The type must implement Event and not be a nil value.
 func Register(ctx context.Context, lis ...Event) error {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	for _, e := range lis {
@@ -84,7 +84,7 @@ func Register(ctx context.Context, lis ...Event) error {
 	return nil
 }
 func RegisterName(ctx context.Context, name string, e Event) error {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	if e == nil {
@@ -119,7 +119,7 @@ func RegisterName(ctx context.Context, name string, e Event) error {
 	return nil
 }
 func GetContainer(ctx context.Context, s string) Event {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	var e Event
@@ -176,7 +176,7 @@ func MarshalBinary(e Event) (txt []byte, err error) {
 }
 
 func UnmarshalBinary(ctx context.Context, txt []byte, pos uint64) (e Event, err error) {
-	_, span := lg.Span(ctx)
+	ctx, span := lg.Span(ctx)
 	defer span.End()
 
 	sp := bytes.SplitN(txt, []byte{'\t'}, 4)
@@ -194,6 +194,8 @@ func UnmarshalBinary(ctx context.Context, txt []byte, pos uint64) (e Event, err
 
 	m.StreamID = string(sp[1])
 	m.Position = pos
+	m.ActualStreamID = string(sp[1])
+	m.ActualPosition = pos
 
 	eventType := string(sp[2])
 	e = GetContainer(ctx, eventType)

pkg/es/graph.go

@@ -15,6 +15,7 @@ import (
 type EventResolver interface {
 	Events(ctx context.Context, streamID string, paging *gql.PageInput) (*gql.Connection, error)
 	EventAdded(ctx context.Context, streamID string, after int64) (<-chan *GQLEvent, error)
+	TruncateStream(ctx context.Context, streamID string, index int64) (bool, error)
 }
 type contextKey struct {
 	name string
@@ -112,11 +113,21 @@ func (e *EventStore) EventAdded(ctx context.Context, streamID string, after int6
 
 	return ch, nil
 }
+func (es *EventStore) TruncateStream(ctx context.Context, streamID string, index int64) (bool, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
+	err := es.Truncate(ctx, streamID, index)
+	return err == nil, err
+}
 func (*EventStore) RegisterHTTP(*http.ServeMux) {}
 func (e *EventStore) GetMiddleware() func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			r = r.WithContext(gql.ToContext(r.Context(), esKey, e))
+			ctx, span := lg.Span(r.Context())
+			defer span.End()
+
+			r = r.WithContext(gql.ToContext(ctx, esKey, e))
 			next.ServeHTTP(w, r)
 		})
 	}
@@ -132,6 +143,12 @@ func (e *GQLEvent) ID() string {
 func (e *GQLEvent) EventID() string {
 	return e.e.EventMeta().GetEventID()
 }
+func (e *GQLEvent) StreamID() string {
+	return e.e.EventMeta().StreamID
+}
+func (e *GQLEvent) Position() uint64 {
+	return e.e.EventMeta().Position
+}
 func (e *GQLEvent) Type() string {
 	return event.TypeOf(e.e)
 }
@@ -150,6 +167,9 @@ func (e *GQLEvent) Meta() *event.Meta {
 	return &meta
 }
 func (e *GQLEvent) Linked(ctx context.Context) (*GQLEvent, error) {
+	ctx, span := lg.Span(ctx)
+	defer span.End()
+
 	values := event.Values(e.e)
 	streamID, ok := values["stream_id"].(string)
 	if !ok {