polardbxengine/unittest/gunit/innodb/lob/lot0buf.cc

/*****************************************************************************

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*****************************************************************************/
#include <string.h>
#include <cassert>
#include <iostream>
#include <map>
#include <set>

#include "lot0buf.h"
#include "mach0data.h"
#include "ut0byte.h"
#include "ut0ut.h"

#ifdef UNIV_DEBUG
#define Fname(x) const char *fname = x;
#define LOG(x) \
  { std::cout << fname << ":" << x << std::endl; }
#else
#define Fname(x)
#define LOG(x)
#endif /* UNIV_DEBUG */

const ulint buf_pool_size = GB1;

class buf_pool_t {
 public:
  buf_pool_t() {
    Fname("buf_pool_t::buf_pool_t");
    ulint page_count;
    LOG("Requested buffer pool size = " << MB100);
    ulint mem_size = ut_2pow_round(buf_pool_size, UNIV_PAGE_SIZE);
    LOG("Will be allocating = " << mem_size);
    page_count = mem_size / UNIV_PAGE_SIZE;
    LOG("Number of pages = " << page_count);
    m_frame_array_raw = new (std::nothrow) byte[mem_size];
    m_frames = (byte *)ut_align(m_frame_array_raw, UNIV_PAGE_SIZE);
    LOG("Raw ptr = " << (void *)m_frame_array_raw);
    LOG("Aligned ptr = " << (void *)m_frames);
    if (m_frame_array_raw != m_frames) {
      --page_count;
    }
    m_cur_free_frame = m_frames;
    m_frame_end = m_frames + page_count * UNIV_PAGE_SIZE;
  }

  /** Get the buffer block, given the page number.  It is an error to
  look for a page number that is not there in the buffer pool.
  @param[in]  page_no  the page number to look for in the buffer pool. */
  buf_block_t *get(page_no_t page_no) {
    auto it = m_buf_pool.find(page_no);
    assert(it != m_buf_pool.end());

    /* Free page must not be accessed. */
    ut_ad(m_free_pages.find(it->second) == m_free_pages.end());
    return (it->second);
  }

  /** Allocate a new page. */
  buf_block_t *alloc() {
    if (!m_free_pages.empty()) {
      auto it = m_free_pages.begin();
      buf_block_t *tmp = *it;
      m_free_pages.erase(it);
      return (tmp);
    }
    return (alloc(max_page_no()));
  }

  void reset() {
    m_free_pages.clear();
    m_buf_pool.clear();
    m_cur_free_frame = m_frames;
  }

  void dealloc(buf_block_t *block) { m_free_pages.insert(block); }

 private:
  buf_block_t *alloc(page_no_t page_no) {
    Fname("buf_pool_t::alloc");
    buf_block_t *block = new (std::nothrow) buf_block_t;
    assert(block != nullptr);
    /* Ensure that the page_no is not already allocated. */
    assert(m_buf_pool.find(page_no) == m_buf_pool.end());
    /* Allocate the new page. */
    block->m_frame = alloc_frame();
    assert(block->m_frame != nullptr);
    /* Initialize the page with zeroes */
    memset(block->m_frame, 0x00, UNIV_PAGE_SIZE);
    /* Set the page number */
    block->set_page_no(page_no);
    m_buf_pool.insert(std::pair<page_no_t, buf_block_t *>(page_no, block));
    LOG("block ptr=" << (void *)block);
    LOG("frame ptr=" << (void *)block->m_frame);
    LOG("page_no=" << page_no);
    return (block);
  }

  page_no_t max_page_no() const { return (m_buf_pool.size()); }

  byte *alloc_frame() {
    byte *tmp = m_cur_free_frame;
    ut_a(m_cur_free_frame != m_frame_end);
    m_cur_free_frame += UNIV_PAGE_SIZE;
    return (tmp);
  }

  /** Copy constructor is disabled. */
  buf_pool_t(const buf_pool_t &other);

  /** The map between the page number, and the actual page. */
  std::map<page_no_t, buf_block_t *> m_buf_pool;

  /** One big chunk containing all frames (unaligned). */
  byte *m_frame_array_raw;

  /** First frame in the array, aligned to page size. */
  byte *m_frames;

  /** End of frame in the array, aligned to page size. */
  byte *m_frame_end;

  /** Current free frame */
  byte *m_cur_free_frame;

  /** Free pages. */
  std::set<buf_block_t *> m_free_pages;
};

static buf_pool_t g_buf_pool;

buf_block_t *buf_page_get(page_no_t page_no) {
  return (g_buf_pool.get(page_no));
}

buf_block_t *btr_page_alloc() { return (g_buf_pool.alloc()); }

void btr_page_free(buf_block_t *block) { return (g_buf_pool.dealloc(block)); }

void buf_pool_reset() { g_buf_pool.reset(); }