CMU15-455BufferPool調試過程

從這個測試用例入手

// NOLINTNEXTLINE
TEST(BufferPoolManagerTest, SampleTest) {
  const std::string db_name = "test.db";
  const size_t buffer_pool_size = 10;

  auto *disk_manager = new DiskManager(db_name);
  auto *bpm = new BufferPoolManager(buffer_pool_size, disk_manager);

  page_id_t page_id_temp;
  auto *page0 = bpm->NewPage(&page_id_temp);

  // Scenario: The buffer pool is empty. We should be able to create a new page.
  ASSERT_NE(nullptr, page0);
  EXPECT_EQ(0, page_id_temp);

  // Scenario: Once we have a page, we should be able to read and write content.
  snprintf(page0->GetData(), PAGE_SIZE, "Hello");
  EXPECT_EQ(0, strcmp(page0->GetData(), "Hello"));

  // Scenario: We should be able to create new pages until we fill up the buffer pool.
  for (size_t i = 1; i < buffer_pool_size; ++i) {
    EXPECT_NE(nullptr, bpm->NewPage(&page_id_temp));
  }

  // Scenario: Once the buffer pool is full, we should not be able to create any new pages.
  for (size_t i = buffer_pool_size; i < buffer_pool_size * 2; ++i) {
    EXPECT_EQ(nullptr, bpm->NewPage(&page_id_temp));
  }

  // Scenario: After unpinning pages {0, 1, 2, 3, 4} and pinning another 4 new pages,
  // there would still be one buffer page left for reading page 0.
  for (int i = 0; i < 5; ++i) {
    EXPECT_EQ(true, bpm->UnpinPage(i, true));
  }
  for (int i = 0; i < 4; ++i) {
    EXPECT_NE(nullptr, bpm->NewPage(&page_id_temp));
  }

  // Scenario: We should be able to fetch the data we wrote a while ago.
  page0 = bpm->FetchPage(0);
  EXPECT_EQ(0, strcmp(page0->GetData(), "Hello"));
  // Scenario: If we unpin page 0 and then make a new page, all the buffer pages should
  // now be pinned. Fetching page 0 should fail.
  EXPECT_EQ(true, bpm->UnpinPage(0, true));
  EXPECT_NE(nullptr, bpm->NewPage(&page_id_temp));
  EXPECT_EQ(nullptr, bpm->FetchPage(0));
  // Shutdown the disk manager and remove the temporary file we created.
  disk_manager->ShutDown();
  remove("test.db");

  delete bpm;
  delete disk_manager;
}

Debug中