// goMerge takes existing and update byte slices. It first attempts
// to gob-unmarshal the update string, returning an error on failure.
// The unmarshaled value must satisfy the Mergable interface.
// Next, it unmarshals the existing string, falling back to the init
// value supplied by the update value's Init() method if necessary.
// The two values obtained in this way are merged and the result, or
// an error, returned.
func goMerge(existing, update []byte) ([]byte, error) {
u, err := encoding.GobDecode(update)
if err != nil {
return nil, util.Errorf("merge: %v", err)
}
if _, ok := u.(Mergable); !ok {
return nil, util.Error("update is not Mergable")
}
e, err := encoding.GobDecode(existing)
if err != nil {
e = u.(Mergable).Init(existing)
}
if reflect.TypeOf(u) != reflect.TypeOf(e) {
return nil, util.Error("cannot merge values of different type")
}
newValue, err := e.(Mergable).Merge(u.(Mergable))
if err != nil {
return nil, err
}
return encoding.GobEncode(newValue)
}
// Slice returns the data stored in the underlying storage.
func (es *EngineSampleStorage) Slice() []interface{} {
startKey := MakeKey(es.prefix, keyDataPrefix)
res, err := es.engine.scan(
startKey, PrefixEndKey(startKey), es.Seen())
if err != nil {
glog.Warning(err)
return nil
}
sl := make([]interface{}, len(res))
for i, kv := range res {
if dv, err := encoding.GobDecode(kv.value); err == nil {
sl[i] = dv
} else {
glog.Warning(err)
}
}
return sl
}