From 46c95940812ccd3f474dc5fab7a5351351e8f105 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Thu, 6 Aug 2015 12:39:07 -0400
Subject: [PATCH] trie: run codec tests, add benchmarks, faster

---
 trie/encoding.go      | 36 ++++++++++++---------------
 trie/encoding_test.go | 58 ++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 70 insertions(+), 24 deletions(-)

diff --git a/trie/encoding.go b/trie/encoding.go
index 8daf503a3f..9c862d78fa 100644
--- a/trie/encoding.go
+++ b/trie/encoding.go
@@ -16,10 +16,6 @@
 
 package trie
 
-import (
-	"bytes"
-)
-
 func CompactEncode(hexSlice []byte) []byte {
 	terminator := 0
 	if hexSlice[len(hexSlice)-1] == 16 {
@@ -38,12 +34,12 @@ func CompactEncode(hexSlice []byte) []byte {
 		hexSlice = append([]byte{flags, 0}, hexSlice...)
 	}
 
-	var buff bytes.Buffer
-	for i := 0; i < len(hexSlice); i += 2 {
-		buff.WriteByte(byte(16*hexSlice[i] + hexSlice[i+1]))
+	l := len(hexSlice) / 2
+	var buf = make([]byte, l)
+	for i := 0; i < l; i++ {
+		buf[i] = 16*hexSlice[2*i] + hexSlice[2*i+1]
 	}
-
-	return buff.Bytes()
+	return buf
 }
 
 func CompactDecode(str []byte) []byte {
@@ -62,22 +58,22 @@ func CompactDecode(str []byte) []byte {
 }
 
 func CompactHexDecode(str []byte) []byte {
-	var nibbles []byte
-
-	for _, b := range str {
-		nibbles = append(nibbles, b/16)
-		nibbles = append(nibbles, b%16)
+	l := len(str)*2 + 1
+	var nibbles = make([]byte, l)
+	for i, b := range str {
+		nibbles[i*2] = b / 16
+		nibbles[i*2+1] = b % 16
 	}
-	nibbles = append(nibbles, 16)
+	nibbles[l-1] = 16
 	return nibbles
 }
 
-// assumes key is odd length
 func DecodeCompact(key []byte) []byte {
-	var res []byte
-	for i := 0; i < len(key)-1; i += 2 {
-		v1, v0 := key[i], key[i+1]
-		res = append(res, v1*16+v0)
+	l := len(key) / 2
+	var res = make([]byte, l)
+	for i := 0; i < l; i++ {
+		v1, v0 := key[2*i], key[2*i+1]
+		res[i] = v1*16 + v0
 	}
 	return res
 }
diff --git a/trie/encoding_test.go b/trie/encoding_test.go
index faaa7f5833..e49b57ef02 100644
--- a/trie/encoding_test.go
+++ b/trie/encoding_test.go
@@ -17,9 +17,14 @@
 package trie
 
 import (
+	"encoding/hex"
+	"testing"
+
 	checker "gopkg.in/check.v1"
 )
 
+func Test(t *testing.T) { checker.TestingT(t) }
+
 type TrieEncodingSuite struct{}
 
 var _ = checker.Suite(&TrieEncodingSuite{})
@@ -28,22 +33,22 @@ func (s *TrieEncodingSuite) TestCompactEncode(c *checker.C) {
 	// even compact encode
 	test1 := []byte{1, 2, 3, 4, 5}
 	res1 := CompactEncode(test1)
-	c.Assert(res1, checker.Equals, "\x11\x23\x45")
+	c.Assert(res1, checker.DeepEquals, []byte("\x11\x23\x45"))
 
 	// odd compact encode
 	test2 := []byte{0, 1, 2, 3, 4, 5}
 	res2 := CompactEncode(test2)
-	c.Assert(res2, checker.Equals, "\x00\x01\x23\x45")
+	c.Assert(res2, checker.DeepEquals, []byte("\x00\x01\x23\x45"))
 
 	//odd terminated compact encode
 	test3 := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
 	res3 := CompactEncode(test3)
-	c.Assert(res3, checker.Equals, "\x20\x0f\x1c\xb8")
+	c.Assert(res3, checker.DeepEquals, []byte("\x20\x0f\x1c\xb8"))
 
 	// even terminated compact encode
 	test4 := []byte{15, 1, 12, 11, 8 /*term*/, 16}
 	res4 := CompactEncode(test4)
-	c.Assert(res4, checker.Equals, "\x3f\x1c\xb8")
+	c.Assert(res4, checker.DeepEquals, []byte("\x3f\x1c\xb8"))
 }
 
 func (s *TrieEncodingSuite) TestCompactHexDecode(c *checker.C) {
@@ -73,3 +78,48 @@ func (s *TrieEncodingSuite) TestCompactDecode(c *checker.C) {
 	res = CompactDecode([]byte("\x3f\x1c\xb8"))
 	c.Assert(res, checker.DeepEquals, exp)
 }
+
+func (s *TrieEncodingSuite) TestDecodeCompact(c *checker.C) {
+	exp, _ := hex.DecodeString("012345")
+	res := DecodeCompact([]byte{0, 1, 2, 3, 4, 5})
+	c.Assert(res, checker.DeepEquals, exp)
+
+	exp, _ = hex.DecodeString("012345")
+	res = DecodeCompact([]byte{0, 1, 2, 3, 4, 5, 16})
+	c.Assert(res, checker.DeepEquals, exp)
+
+	exp, _ = hex.DecodeString("abcdef")
+	res = DecodeCompact([]byte{10, 11, 12, 13, 14, 15})
+	c.Assert(res, checker.DeepEquals, exp)
+}
+
+func BenchmarkCompactEncode(b *testing.B) {
+
+	testBytes := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
+	for i := 0; i < b.N; i++ {
+		CompactEncode(testBytes)
+	}
+}
+
+func BenchmarkCompactDecode(b *testing.B) {
+	testBytes := []byte{0, 15, 1, 12, 11, 8 /*term*/, 16}
+	for i := 0; i < b.N; i++ {
+		CompactDecode(testBytes)
+	}
+}
+
+func BenchmarkCompactHexDecode(b *testing.B) {
+	testBytes := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
+	for i := 0; i < b.N; i++ {
+		CompactHexDecode(testBytes)
+	}
+
+}
+
+func BenchmarkDecodeCompact(b *testing.B) {
+	testBytes := []byte{7, 6, 6, 5, 7, 2, 6, 2, 16}
+	for i := 0; i < b.N; i++ {
+		DecodeCompact(testBytes)
+	}
+
+}