Sink: add Reset() and Len() to the interface

Signed-off-by: Alejandro Mery <[email protected]>

cache.go

@@ -81,9 +81,16 @@ type Sink interface {
  // of bytes
  Bytes() []byte
 
+ // Len tells the length of the internally encoded
+ // representation of the value
+ Len() int
+
  // Expire returns the time whe this entry will
  // be evicted from the Cache
  Expire() time.Time
+
+ // Reset empties the content of the Sink
+ Reset()
 }
 
 // A Getter loads data for a key.

gob.go

@@ -23,10 +23,15 @@ type GobSink[T any] struct {
 // Bytes returns the Gob encoded representation of the object
 // in the Sink
 func (sink *GobSink[T]) Bytes() []byte {
- // TODO: do we need to copy them?
  return sink.bytes
 }
 
+// Len returns the length of the Gob encoded representation of the
+// object in the Sink. 0 if empty.
+func (sink *GobSink[T]) Len() int {
+ return len(sink.bytes)
+}
+
 // Expire tells when this object will be evicted from the Cache
 func (sink *GobSink[T]) Expire() time.Time {
  return sink.e