Refactor serialization helpers from impl/memory -> service/datastore/serialize

service/datastore/serialize/binary_tools.go

Index: service/datastore/serialize/binary_tools.go
diff --git a/service/datastore/serialize/binary_tools.go b/service/datastore/serialize/binary_tools.go
new file mode 100644
index 0000000000000000000000000000000000000000..a0b9e7ee5268e923a6e510fd5ba31a27a8c6067a
--- /dev/null
+++ b/service/datastore/serialize/binary_tools.go
@@ -0,0 +1,53 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package serialize
+
+// Join will allocate a new []byte large enough to contain all itms and return
+// it.
+//
+// If itms only has one element, this effectively just copies that one element.
+func Join(itms ...[]byte) []byte {

[Vadim Sh., 2015/09/24 19:06:14]

consider using https://golang.org/pkg/bytes/#Join

[iannucci, 2015/09/24 19:43:41]

LOL! TIL....

+	total := 0
+	for _, i := range itms {
+		total += len(i)
+	}
+	if total == 0 {
+		return nil
+	}
+	ret := make([]byte, 0, total)
+	for _, i := range itms {
+		ret = append(ret, i...)
+	}
+	return ret
+}
+
+// Invert simply inverts all the bytes in bs.
+func Invert(bs []byte) []byte {
+	if len(bs) == 0 {
+		return nil
+	}
+	ret := make([]byte, len(bs))
+	for i, b := range bs {
+		ret[i] = 0xFF ^ b
+	}
+	return ret
+}
+
+// Increment attempts to increment a copy of bstr as if adding 1 to an integer.
+//
+// If it overflows, the returned []byte will be all 0's, and the overflow bool
+// will be true.
+func Increment(bstr []byte) ([]byte, bool) {
+	ret := Join(bstr)

[Vadim Sh., 2015/09/24 19:06:14]

append(nil, bstr...) is a common pattern for copying afaik 

[iannucci, 2015/09/24 19:43:41]

Hm... Is that efficient? Probably...

It's more verbose though `append([]byte(nil), bstr...)`

+	for i := len(ret) - 1; i >= 0; i-- {
+		if ret[i] == 0xFF {
+			ret[i] = 0
+		} else {
+			ret[i]++
+			return ret, false
+		}
+	}
+	return ret, true
+}