components/network_hints/renderer/dns_prefetch_queue_unittest.cc

   1 // Copyright (c) 2010 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 <sstream>
   6
   7 #include "components/network_hints/renderer/dns_prefetch_queue.h"
   8 #include "testing/gtest/include/gtest/gtest.h"
   9
  10 // Single threaded tests of DnsQueue functionality.
  11
  12 namespace network_hints {
  13
  14 class DnsQueueTest : public testing::Test {
  15 };
  16
  17 // Define a helper class that does Push'es and Pop's of numbers.
  18 // This makes it easy to test a LOT of reads, and keep the expected Pop
  19 // value in sync with the Push value.
  20 class DnsQueueSequentialTester {
  21  public:
  22   DnsQueueSequentialTester(DnsQueue& buffer, int32 read_counter = 0,
  23                            int32 write_counter = 0);
  24
  25   // Return of false means buffer was full, or would not take entry.
  26   bool Push(void);  // Push the string value of next number.
  27
  28   // Return of false means buffer returned wrong value.
  29   bool Pop(void);  // Validate string value of next read.
  30
  31  private:
  32   DnsQueue* buffer_;
  33   int32 read_counter_;  // expected value of next read string.
  34   int32 write_counter_;  // Numerical value to write next string.
  35   DISALLOW_COPY_AND_ASSIGN(DnsQueueSequentialTester);
  36 };
  37
  38
  39 DnsQueueSequentialTester::DnsQueueSequentialTester(
  40   DnsQueue& buffer, int32 read_counter, int32 write_counter)
  41     : buffer_(&buffer),
  42       read_counter_(read_counter),
  43       write_counter_(write_counter) {
  44 }
  45
  46 bool DnsQueueSequentialTester::Push(void) {
  47   std::ostringstream value;
  48   value << write_counter_;
  49
  50   // Exercise both write methods intermittently.
  51   DnsQueue::PushResult result = (write_counter_ % 2) ?
  52        buffer_->Push(value.str().c_str(), value.str().size()) :
  53        buffer_->Push(value.str());
  54   if (DnsQueue::SUCCESSFUL_PUSH == result)
  55     write_counter_++;
  56   return DnsQueue::OVERFLOW_PUSH != result;
  57 }
  58
  59 bool DnsQueueSequentialTester::Pop(void) {
  60   std::string string;
  61   if (buffer_->Pop(&string)) {
  62     std::ostringstream expected_value;
  63     expected_value << read_counter_++;
  64     EXPECT_STREQ(expected_value.str().c_str(), string.c_str())
  65         << "Pop did not match write for value " << read_counter_;
  66     return true;
  67   }
  68   return false;
  69 }
  70
  71
  72 TEST(DnsQueueTest, BufferUseCheck) {
  73   // Use a small buffer so we can see that we can't write a string as soon as it
  74   // gets longer than one less than the buffer size.  The extra empty character
  75   // is used to keep read and write pointers from overlapping when buffer is
  76   // full.  This shows the buffer size can constrain writes (and we're not
  77   // scribbling all over memory).
  78   const int buffer_size = 3;  // Just room for 2 digts plus '\0' plus blank.
  79   std::string string;
  80   DnsQueue buffer(buffer_size);
  81   DnsQueueSequentialTester tester(buffer);
  82
  83   EXPECT_FALSE(tester.Pop()) << "Pop from empty buffer succeeded";
  84
  85   int i;
  86   for (i = 0; i < 102; i++) {
  87     if (!tester.Push())
  88       break;  // String was too large.
  89     EXPECT_TRUE(tester.Pop()) << "Unable to read back data " << i;
  90     EXPECT_FALSE(buffer.Pop(&string))
  91                 << "read from empty buffer not flagged";
  92   }
  93
  94   EXPECT_GE(i, 100) << "Can't write 2 digit strings in 4 character buffer";
  95   EXPECT_LT(i, 101) << "We wrote 3 digit strings into a 4 character buffer";
  96 }
  97
  98 TEST(DnsQueueTest, SubstringUseCheck) {
  99   // Verify that only substring is written/read.
 100   const int buffer_size = 100;
 101   const char big_string[] = "123456789";
 102   std::string string;
 103   DnsQueue buffer(buffer_size);
 104
 105   EXPECT_FALSE(buffer.Pop(&string)) << "Initial buffer not empty";
 106
 107   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push(big_string, 3))
 108       << "Can't write string";
 109   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push(big_string, 0))
 110       << "Can't write null string";
 111   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push(big_string, 5))
 112       << "Can't write string";
 113
 114   EXPECT_TRUE(buffer.Pop(&string)) << "Filled buffer marked as empty";
 115   EXPECT_STREQ(string.c_str(), "123") << "Can't read actual data";
 116   EXPECT_TRUE(buffer.Pop(&string)) << "Filled buffer marked as empty";
 117   EXPECT_STREQ(string.c_str(), "") << "Can't read null string";
 118   EXPECT_TRUE(buffer.Pop(&string)) << "Filled buffer marked as empty";
 119   EXPECT_STREQ(string.c_str(), "12345") << "Can't read actual data";
 120
 121   EXPECT_FALSE(buffer.Pop(&string))
 122               << "read from empty buffer not flagged";
 123 }
 124
 125 TEST(DnsQueueTest, SizeCheck) {
 126   // Verify that size is correctly accounted for in buffer.
 127   const int buffer_size = 100;
 128   std::string input_string = "Hello";
 129   std::string string;
 130   DnsQueue buffer(buffer_size);
 131
 132   EXPECT_EQ(0U, buffer.Size());
 133   EXPECT_FALSE(buffer.Pop(&string));
 134   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push(input_string));
 135   EXPECT_EQ(1U, buffer.Size());
 136   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push("Hi There"));
 137   EXPECT_EQ(2U, buffer.Size());
 138   EXPECT_TRUE(buffer.Pop(&string));
 139   EXPECT_EQ(1U, buffer.Size());
 140   EXPECT_TRUE(buffer.Pop(&string));
 141   EXPECT_EQ(0U, buffer.Size());
 142   EXPECT_EQ(DnsQueue::SUCCESSFUL_PUSH, buffer.Push(input_string));
 143   EXPECT_EQ(1U, buffer.Size());
 144
 145   // Check to see that the first string, if repeated, is discarded.
 146   EXPECT_EQ(DnsQueue::REDUNDANT_PUSH, buffer.Push(input_string));
 147   EXPECT_EQ(1U, buffer.Size());
 148 }
 149
 150 TEST(DnsQueueTest, FillThenEmptyCheck) {
 151   // Use a big buffer so we'll get a bunch of writes in.
 152   // This tests to be sure the buffer holds many strings.
 153   // We also make sure they all come out intact.
 154   const size_t buffer_size = 1000;
 155   size_t byte_usage_counter = 1;  // Separation character between pointer.
 156   DnsQueue buffer(buffer_size);
 157   DnsQueueSequentialTester tester(buffer);
 158
 159   size_t write_success;
 160   for (write_success = 0; write_success < buffer_size; write_success++) {
 161     if (!tester.Push())
 162       break;
 163     EXPECT_EQ(buffer.Size(), write_success + 1);
 164     if (write_success > 99)
 165       byte_usage_counter += 4;  // 3 digit plus '\0'.
 166     else if (write_success > 9)
 167       byte_usage_counter += 3;  // 2 digits plus '\0'.
 168     else
 169       byte_usage_counter += 2;  // Digit plus '\0'.
 170   }
 171   EXPECT_LE(byte_usage_counter, buffer_size)
 172       << "Written data exceeded buffer size";
 173   EXPECT_GE(byte_usage_counter, buffer_size - 4)
 174       << "Buffer does not appear to have filled";
 175
 176   EXPECT_GE(write_success, 10U) << "Couldn't even write 10 one digit strings "
 177       "in " << buffer_size << " byte buffer";
 178
 179
 180   while (1) {
 181     if (!tester.Pop())
 182       break;
 183     write_success--;
 184   }
 185   EXPECT_EQ(write_success, 0U) << "Push and Pop count were different";
 186
 187   EXPECT_FALSE(tester.Pop()) << "Read from empty buffer succeeded";
 188 }
 189
 190 TEST(DnsQueueTest, ClearCheck) {
 191   // Use a big buffer so we'll get a bunch of writes in.
 192   const size_t buffer_size = 1000;
 193   DnsQueue buffer(buffer_size);
 194   std::string string("ABC");
 195   DnsQueueSequentialTester tester(buffer);
 196
 197   size_t write_success;
 198   for (write_success = 0; write_success < buffer_size; write_success++) {
 199     if (!tester.Push())
 200       break;
 201     EXPECT_EQ(buffer.Size(), write_success + 1);
 202   }
 203
 204   buffer.Clear();
 205   EXPECT_EQ(buffer.Size(), 0U);
 206
 207   size_t write_success2;
 208   for (write_success2 = 0; write_success2 < buffer_size; write_success2++) {
 209     if (!tester.Push())
 210       break;
 211     EXPECT_EQ(buffer.Size(), write_success2 + 1);
 212   }
 213
 214   for (; write_success2 > 0; write_success2--) {
 215     EXPECT_EQ(buffer.Size(), write_success2);
 216     EXPECT_TRUE(buffer.Pop(&string));
 217   }
 218
 219   EXPECT_EQ(buffer.Size(), 0U);
 220   buffer.Clear();
 221   EXPECT_EQ(buffer.Size(), 0U);
 222 }
 223
 224 TEST(DnsQueueTest, WrapOnVariousSubstrings) {
 225   // Use a prime number for the allocated buffer size so that we tend
 226   // to exercise all possible edge conditions (in circular text buffer).
 227   // Once we're over 10 writes, all our strings are 2 digits long,
 228   // with a '\0' terminator added making 3 characters per write.
 229   // Since 3 is relatively prime to 23, we'll soon wrap (about
 230   // every 6 writes).  Hence after 18 writes, we'll have tested all
 231   // edge conditions.  We'll first do this where we empty the buffer
 232   // after each write, and then again where there are some strings
 233   // still in the buffer after each write.
 234   const int prime_number = 23;
 235   // Circular buffer needs an extra extra space to distinguish full from empty.
 236   const int buffer_size = prime_number - 1;
 237   DnsQueue buffer(buffer_size);
 238   DnsQueueSequentialTester tester(buffer);
 239
 240   // First test empties between each write. Second loop
 241   // has writes for each pop.  Third has three pushes per pop.
 242   // Third has two items pending during each write.
 243   for (int j = 0; j < 3; j++) {
 244     // Each group does 30 tests, which is more than 10+18
 245     // which was needed to get into the thorough testing zone
 246     // mentioned above.
 247     for (int i = 0; i < 30; i++) {
 248       EXPECT_TRUE(tester.Push()) << "write failed with only " << j
 249                                     << " blocks in buffer";
 250       EXPECT_TRUE(tester.Pop()) << "Unable to read back data ";
 251     }
 252     EXPECT_TRUE(tester.Push());
 253   }
 254
 255   // Read back the accumulated 3 extra blocks.
 256   EXPECT_TRUE(tester.Pop());
 257   EXPECT_TRUE(tester.Pop());
 258   EXPECT_TRUE(tester.Pop());
 259   EXPECT_FALSE(tester.Pop());
 260 }
 261
 262 };  // namespace network_hints