kernel/vm/TransientSlotPool.cpp

/*
   Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

#include "record_types.hpp"
#include "IntrusiveList.hpp"
#include "TransientPagePool.hpp"
#include "TransientSlotPool.hpp"

#define JAM_FILE_ID 505

TransientSlotPool::TransientSlotPool()
: m_page_pool(NULL),
  m_type_id(0),
//  m_slot_size(0),
  m_use_count(0),
//  m_use_high(0),
  m_may_shrink(false)//,
//  m_shrink_level(0),
//  m_static_initialized_slots(0)
{
  m_free_list.init();
}


void TransientSlotPool::init(Uint32 type_id,
                             Uint32 slot_size,
                             Uint32* min_recs,
                             const Pool_context& pool_ctx)
{
//  const Uint32 slots_per_page = Page::DATA_WORDS_PER_PAGE / slot_size;

  m_page_pool = new TransientPagePool(type_id,
                                      pool_ctx.get_mem_manager());
  m_type_id = type_id;
*min_recs = 0;
  // m_slot_size = slot_size;
  // m_shrink_level = m_static.getSize() + (slots_per_page + 1) / 2;
  // require(expand());
}


TransientSlotPool::~TransientSlotPool()
{
  if (m_page_pool)
  {
    delete m_page_pool;
  }
}


bool TransientSlotPool::expand(Uint32 slot_size)
{
  assert(m_free_list.isEmpty());
  Ptr<TransientPagePool::Page> lpage;
  if (unlikely(!m_page_pool->seize(lpage)))
  {
    return false;
  }
  Ptr<Page> page;
  page.i = lpage.i;
  page.p = reinterpret_cast<Page*>(lpage.p);

  page.p->m_use_count = 0;
  m_may_shrink = m_page_pool->getTopPageNumber() > 0;

  // Add first slot to free list
  const Uint32 slots_per_page = Page::DATA_WORDS_PER_PAGE / slot_size;
  LocalSlotPool<TransientSlotPool> pool(this, slot_size);
  Ptr<Type> free_record;
  void *pv = static_cast<void*>(&page.p->m_data[0]);
  free_record.p = new (pv) Type;
  free_record.i = slots_per_page * page.i;
  Slot_list free_list(pool, m_free_list);
  free_list.addLast(free_record);
  page.p->m_first_in_free_array = 1;

  return true;
}

Uint64 TransientSlotPool::getMemoryNeed(Uint32 slot_size, Uint32 entry_count)
{
  const Uint64 entries_per_page = (Page::DATA_WORDS_PER_PAGE / slot_size);
  const Uint64 data_pages =
      ((entry_count + entries_per_page - 1) / entries_per_page);
  return data_pages * sizeof(Page) + TransientPagePool::getMemoryNeed(data_pages);
}

Uint32 TransientSlotPool::getUncheckedPtrs(Uint32* from,
                                           Ptr<Type> ptrs[],
                                           Uint32 cnt,
                                           Uint32 slot_size) const
{
  Uint32 index = *from;
  const Uint32 slots_per_page = Page::DATA_WORDS_PER_PAGE / slot_size;
  Uint32 page_number = index / slots_per_page;
  Uint32 page_index = index % slots_per_page;
  require(index != RNIL);

  Ptr<TransientPagePool::Page> lpage;
  lpage.i = page_number;
  if (unlikely(!m_page_pool->getUncheckedPtr(lpage)))
  {
    Uint32 top_page = m_page_pool->getTopPageNumber();
    if (top_page == RNIL || page_number >= top_page)
    {
      index = RNIL;
    }
    else
    {
      index = index - page_index + slots_per_page;
    }
    *from = index;
    return 0;
  }
  Page* page = reinterpret_cast<Page*>(lpage.p);
  const Uint32 end_index = page->m_first_in_free_array;
  Uint32 *slot_ptr = &page->m_data[page_index * slot_size];
  Uint32 ptrs_cnt = 0;
  for (; ptrs_cnt < cnt && page_index < end_index;
         page_index++, index++, ptrs_cnt++, slot_ptr += slot_size)
  {
    ptrs[ptrs_cnt].i = index;
    ptrs[ptrs_cnt].p = reinterpret_cast<Type*>(slot_ptr);
  }
  if (unlikely(page_index >= end_index))
  {
    Uint32 top_page = m_page_pool->getTopPageNumber();
    require(top_page != RNIL);
    if (page_number == top_page)
    {
      index = RNIL;
    }
    else if (page_index < slots_per_page)
    {
      require(page_number < top_page);
      require(page_index == end_index);
      index = index - page_index + slots_per_page;
    }
    else
    {
      require(page_number < top_page);
      require(end_index == slots_per_page);
    }
  }
  *from = index;
  return ptrs_cnt;
}

bool TransientSlotPool::rearrange_free_list_and_shrink(Uint32* max_shrinks, Uint32 slot_size)
{
  Uint32 free = getNoOfFree();
  if (free > 8)
  {
    free = 8;
  }
  if (free > 0)
  {
    Ptr<Type> ptr[8];
    Uint32 j = 0;
    for (Uint32 i = 0; i < free; i++)
    {
      if (likely(seize(ptr[j], slot_size)))
      {
        j++;
      }
    }
    while (j > 0)
    {
      j--;
      release(ptr[j], slot_size);
    }
    free--;
  }
  for (Uint32 shrink_count = 0; shrink_count < *max_shrinks; shrink_count++)
  {
    if (!shrink(slot_size))
    {
*max_shrinks = shrink_count;
      return false;
    }
  }
  return true;
}

bool TransientSlotPool::shrink(Uint32 slot_size)
{
  if(!may_shrink())
  {
    return false;
  }
  Uint32 page_number = m_page_pool->getTopPageNumber();
  require(m_page_pool->canRelease(page_number));
  Ptr<TransientPagePool::Page> lpage;
  lpage.i = page_number;
  require(m_page_pool->getPtr(lpage));
  Page* page = reinterpret_cast<Page*>(lpage.p);
  require(page->m_use_count == 0);

  const Uint32 slots_per_page = Page::DATA_WORDS_PER_PAGE / slot_size;
  Uint32 base_index = slots_per_page * lpage.i;

  {
    LocalSlotPool<TransientSlotPool> pool(this, slot_size);
    Slot_list free_list(pool, m_free_list);
    const Uint32 end_index = page->m_first_in_free_array;
    for (unsigned i = 0; i < end_index; i++)
    {
      Ptr<Type> p;
      p.p = reinterpret_cast<Type*>(&page->m_data[i * slot_size]);
      p.i = base_index + i;
      free_list.remove(p);
    }
  }
  require(m_page_pool->release(lpage));

  lpage.i = m_page_pool->getTopPageNumber();
  if (!m_page_pool->canRelease(lpage.i))
  {
    m_may_shrink = false;
    return false;
  }
  require(m_page_pool->getPtr(lpage));

  page = reinterpret_cast<Page*>(lpage.p);
  if (page->m_use_count != 0)
  {
    m_may_shrink = false;
    return false;
  }
  return true;
}

#if !INLINE_TRANSIENT_SLOT_POOL
#define inline
#include "TransientSlotPool.inline.hpp.inc"
#endif