feat(util): KeyWithUint64 and KeyWithUint32 helper functions for db keys

util/bytes.go

@@ -27,3 +27,21 @@ func UintWithNullPrefix(n uint64) []byte {
 	binary.LittleEndian.PutUint64(bz[1:], n)
 	return bz
 }
+
+// KeyWithUint32 concatenates prefix big endian serialized n value.
+// No zero byte is appended at the end.
+func KeyWithUint32(prefix []byte, n uint32) []byte {
+	out := make([]byte, len(prefix)+4)
+	copy(out, prefix)
+	binary.BigEndian.PutUint32(out[len(prefix):], n)
+	return out
+}
+
+// KeyWithUint64 concatenates prefix big endian serialized n value.
+// No zero byte is appended at the end.
+func KeyWithUint64(prefix []byte, n uint64) []byte {
+	out := make([]byte, len(prefix)+8)
+	copy(out, prefix)
+	binary.BigEndian.PutUint64(out[len(prefix):], n)
+	return out
+}

util/bytes_test.go

@@ -36,3 +36,27 @@ func TestUintWithNullPrefix(t *testing.T) {
 	out := UintWithNullPrefix(math.MaxUint64)
 	assert.DeepEqual(t, expected, out)
 }
+
+func TestKeyWithUint(t *testing.T) {
+	prefix := []byte{1, 10}
+
+	out := KeyWithUint32(nil, 200)
+	assert.DeepEqual(t, out, []byte{0, 0, 0, 200})
+
+	out = KeyWithUint32(prefix, 200)
+	assert.DeepEqual(t, out, []byte{1, 10, 0, 0, 0, 200})
+
+	out = KeyWithUint32(prefix, 256)
+	assert.DeepEqual(t, out, []byte{1, 10, 0, 0, 1, 0})
+
+	// uint64 version
+
+	out = KeyWithUint64(nil, 200)
+	assert.DeepEqual(t, out, []byte{0, 0, 0, 0, 0, 0, 0, 200})
+
+	out = KeyWithUint64(prefix, 200)
+	assert.DeepEqual(t, out, []byte{1, 10, 0, 0, 0, 0, 0, 0, 0, 200})
+
+	out = KeyWithUint64(prefix, 256)
+	assert.DeepEqual(t, out, []byte{1, 10, 0, 0, 0, 0, 0, 0, 1, 0})
+}