delayed: export datastructure type

That way, we can return it directly.

delayed/delayed.go

@@ -9,50 +9,61 @@ import (
 )
 
 // New returns a new delayed datastore.
-func New(ds ds.Datastore, delay delay.D) ds.Datastore {
-	return &delayed{ds: ds, delay: delay}
+func New(ds ds.Datastore, delay delay.D) *Delayed {
+	return &Delayed{ds: ds, delay: delay}
 }
 
-type delayed struct {
+// Delayed is an adapter that delays operations on the inner datastore.
+type Delayed struct {
 	ds    ds.Datastore
 	delay delay.D
 }
 
-func (dds *delayed) Put(key ds.Key, value []byte) (err error) {
+var _ ds.Batching = (*Delayed)(nil)
+
+// Put implements the ds.Datastore interface.
+func (dds *Delayed) Put(key ds.Key, value []byte) (err error) {
 	dds.delay.Wait()
 	return dds.ds.Put(key, value)
 }
 
-func (dds *delayed) Get(key ds.Key) (value []byte, err error) {
+// Get implements the ds.Datastore interface.
+func (dds *Delayed) Get(key ds.Key) (value []byte, err error) {
 	dds.delay.Wait()
 	return dds.ds.Get(key)
 }
 
-func (dds *delayed) Has(key ds.Key) (exists bool, err error) {
+// Has implements the ds.Datastore interface.
+func (dds *Delayed) Has(key ds.Key) (exists bool, err error) {
 	dds.delay.Wait()
 	return dds.ds.Has(key)
 }
 
-func (dds *delayed) GetSize(key ds.Key) (size int, err error) {
+// GetSize implements the ds.Datastore interface.
+func (dds *Delayed) GetSize(key ds.Key) (size int, err error) {
 	dds.delay.Wait()
 	return dds.ds.GetSize(key)
 }
 
-func (dds *delayed) Delete(key ds.Key) (err error) {
+// Delete implements the ds.Datastore interface.
+func (dds *Delayed) Delete(key ds.Key) (err error) {
 	dds.delay.Wait()
 	return dds.ds.Delete(key)
 }
 
-func (dds *delayed) Query(q dsq.Query) (dsq.Results, error) {
+// Query implements the ds.Datastore interface.
+func (dds *Delayed) Query(q dsq.Query) (dsq.Results, error) {
 	dds.delay.Wait()
 	return dds.ds.Query(q)
 }
 
-func (dds *delayed) Batch() (ds.Batch, error) {
+// Batch implements the ds.Batching interface.
+func (dds *Delayed) Batch() (ds.Batch, error) {
 	return ds.NewBasicBatch(dds), nil
 }
 
-func (dds *delayed) DiskUsage() (uint64, error) {
+// DiskUsage implements the ds.PersistentDatastore interface.
+func (dds *Delayed) DiskUsage() (uint64, error) {
 	dds.delay.Wait()
 	return ds.DiskUsage(dds.ds)
 }