Restructure backend

backend/id.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"errors"
+	"sync"
 )
 
 // IDSize contains the size of an ID, in bytes.
@@ -14,6 +15,8 @@ const IDSize = sha256.Size
 // References content within a repository.
 type ID []byte
 
+var idPool = sync.Pool{New: func() interface{} { return ID(make([]byte, IDSize)) }}
+
 // ParseID converts the given string to an ID.
 func ParseID(s string) (ID, error) {
 	b, err := hex.DecodeString(s)