net/spdy/hpack_string_util_test.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/spdy/hpack_string_util.h"
   6
   7 #include <cstddef>
   8 #include <cstring>
   9
  10 #include "base/basictypes.h"
  11 #include "base/logging.h"
  12 #include "base/strings/string_piece.h"
  13 #include "testing/gtest/include/gtest/gtest.h"
  14
  15 namespace net {
  16
  17 namespace {
  18
  19 using std::string;
  20
  21 // Make sure StringPiecesEqualConstantTime() behaves like the regular
  22 // string equality operator.
  23 TEST(HpackStringUtilTest, StringPiecesEqualConstantTime) {
  24   EXPECT_TRUE(StringPiecesEqualConstantTime("foo", "foo"));
  25   EXPECT_FALSE(StringPiecesEqualConstantTime("foo", "foox"));
  26   EXPECT_FALSE(StringPiecesEqualConstantTime("foo", "bar"));
  27 }
  28
  29 // TODO(jgraettinger): Support this benchmark.
  30 /*
  31 enum BM_StringPieceEqualityType {
  32   STRCMP_EQUAL,
  33   STRCMP_FIRST_CHAR_DIFFERS,
  34   STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL,
  35   STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS,
  36 };
  37
  38 void BM_StringPieceEquality(int iters, int size, int type_int) {
  39   BM_StringPieceEqualityType type =
  40       static_cast<BM_StringPieceEqualityType>(type_int);
  41   string str_a(size, 'x');
  42   string str_b(size, 'x');
  43   int result = 0;
  44   switch (type) {
  45     case STRCMP_EQUAL:
  46       for (int i = 0; i < iters; ++i) {
  47         result |= std::strcmp(str_a.c_str(), str_b.c_str());
  48       }
  49       CHECK_EQ(result, 0);
  50       return;
  51
  52     case STRCMP_FIRST_CHAR_DIFFERS:
  53       str_b[0] = 'y';
  54       for (int i = 0; i < iters; ++i) {
  55         result |= std::strcmp(str_a.c_str(), str_b.c_str());
  56       }
  57       CHECK_LT(result, 0);
  58       return;
  59
  60     case STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL:
  61       for (int i = 0; i < iters; ++i) {
  62         result |= StringPiecesEqualConstantTime(str_a, str_b);
  63       }
  64       CHECK_EQ(result, 1);
  65       return;
  66
  67     case STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS:
  68       str_b[0] = 'y';
  69       for (int i = 0; i < iters; ++i) {
  70         result |= StringPiecesEqualConstantTime(str_a, str_b);
  71       }
  72       CHECK_EQ(result, 0);
  73       return;
  74   }
  75
  76   DCHECK(false);
  77 }
  78
  79 // Results should resemble the table below, where 0 and 1 are clearly
  80 // different (STRCMP), but 2 and 3 are roughly the same
  81 // (STRING_PIECES_EQUAL_CONSTANT_TIME).
  82 //
  83 // DEBUG: Benchmark                     Time(ns)    CPU(ns) Iterations
  84 // -------------------------------------------------------------------
  85 // DEBUG: BM_StringPieceEquality/1M/0      77796      77141       7778
  86 // DEBUG: BM_StringPieceEquality/1M/1         10         10   70000000
  87 // DEBUG: BM_StringPieceEquality/1M/2    7729735    7700000        100
  88 // DEBUG: BM_StringPieceEquality/1M/3    7803051    7800000        100
  89 BENCHMARK(BM_StringPieceEquality)
  90   ->ArgPair(1<<20, STRCMP_EQUAL)
  91   ->ArgPair(1<<20, STRCMP_FIRST_CHAR_DIFFERS)
  92   ->ArgPair(1<<20, STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL)
  93   ->ArgPair(1<<20, STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS);
  94 */
  95
  96 }  // namespace
  97
  98 }  // namespace net