技術標籤：演算法

從標頭檔案

buffer_pool_manager.h

的資料成員入手，理出思路：

  /** Number of pages in the buffer pool. */
  size_t pool_size_;
  /** Array of buffer pool pages. */
  Page *pages_;
  /** Pointer to the disk manager. */
  DiskManager *disk_manager_ __attribute__((__unused__));
  /** Pointer to the log manager. */
  LogManager *log_manager_ __attribute__((__unused__));
  /** Page table for keeping track of buffer pool pages. */
  std::unordered_map<page_id_t, frame_id_t> page_table_;
  /** Replacer to find unpinned pages for replacement. */
  Replacer *replacer_;
  /** List of free pages. */
  std::list<frame_id_t> free_list_;
  /** This latch protects shared data structures. We recommend updating this comment to describe what it protects. */
  std::mutex latch_;
 

建立頁表的過程，至少能看懂

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

  std::random_device r;
  std::default_random_engine rng(r());
  std::uniform_int_distribution<char> uniform_dist(0);

  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);

  char random_binary_data[PAGE_SIZE];
  // Generate random binary data
  for (char &i : random_binary_data) {
    i = uniform_dist(rng);
  }

  // Insert terminal characters both in the middle and at end
  random_binary_data[PAGE_SIZE / 2] = '\0';
  random_binary_data[PAGE_SIZE - 1] = '\0';

  // Scenario: Once we have a page, we should be able to read and write content.
  std::memcpy(page0->GetData(), random_binary_data, PAGE_SIZE);
  EXPECT_EQ(0, std::memcmp(page0->GetData(), random_binary_data, PAGE_SIZE));

  // 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));
  }
 

大概理解幾個關鍵資料後，找到思路。未完待續