log_postpone_cache.cpp

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/*
 * Copyright 2008 Search Solution Corporation
 * Copyright 2016 CUBRID Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

/*
 * log_postpone_cache.cpp - log postpone cache module
 */

#include "log_postpone_cache.hpp"

#include "memory_alloc.h"
#include "memory_private_allocator.hpp"
#include "object_representation.h"
#include "log_manager.h"

#include <cstring>

void
log_postpone_cache::reset ()
{
  m_cursor = 0;
  m_redo_data_offset = 0;
  m_is_redo_data_buf_full = false;
  if (m_redo_data_buf.get_size () > BUFFER_RESET_SIZE)
    {
      m_redo_data_buf.freemem ();
    }
}

void
log_postpone_cache::add_redo_data (const log_prior_node &node)
{
  assert (node.data_header != NULL);
  assert (node.rlength == 0 || node.rdata != NULL);
  assert (m_cursor <= MAX_CACHE_ENTRIES);

  if (is_full ())
    {
      // Cannot cache postpones, cache reached max capacity
      return;
    }

  // Check if recovery data fits in preallocated buffer
  std::size_t redo_data_size = sizeof (log_rec_redo) + node.rlength + (2 * MAX_ALIGNMENT);
  std::size_t total_size = redo_data_size + m_redo_data_offset;
  if (total_size > REDO_DATA_MAX_SIZE)
    {
      // Cannot store all recovery data
      m_is_redo_data_buf_full = true;
      return;
    }
  else
    {
      m_redo_data_buf.extend_to (total_size);
    }

  // Cache a new postpone log record entry
  cache_entry &new_entry = m_cache_entries[m_cursor];
  new_entry.m_offset = m_redo_data_offset;
  // first and only first entry has m_offset equal to zero
  assert ((m_cursor == 0) == (new_entry.m_offset == 0));
  new_entry.m_lsa.set_null ();

  // Cache log_rec_redo from data_header
  char *redo_data_ptr = m_redo_data_buf.get_ptr () + m_redo_data_offset;
  memcpy (redo_data_ptr, node.data_header, sizeof (log_rec_redo));
  redo_data_ptr += sizeof (log_rec_redo);
  redo_data_ptr = PTR_ALIGN (redo_data_ptr, MAX_ALIGNMENT);

  // Cache recovery data
  assert (((log_rec_redo *) node.data_header)->length == node.rlength);
  if (node.rlength > 0)
    {
      memcpy (redo_data_ptr, node.rdata, node.rlength);
      redo_data_ptr += node.rlength;
      redo_data_ptr = PTR_ALIGN (redo_data_ptr, MAX_ALIGNMENT);
    }

  m_redo_data_offset = redo_data_ptr - m_redo_data_buf.get_ptr ();
}

void
log_postpone_cache::add_lsa (const log_lsa &lsa)
{
  assert (!lsa.is_null ());

  if (is_full ())
    {
      return;
    }

  assert (m_cursor < MAX_CACHE_ENTRIES);

  m_cache_entries[m_cursor].m_lsa = lsa;

  /* Now that all needed data is saved, increment cached entries counter. */
  m_cursor++;
}

bool
log_postpone_cache::do_postpone (cubthread::entry &thread_ref, const log_lsa &start_postpone_lsa)
{
  assert (!start_postpone_lsa.is_null ());

  if (is_full ())
    {
      // Cache is not usable
      reset ();
      return false;
    }

  // First cached postpone entry at start_postpone_lsa
  int start_index = -1;
  for (std::size_t i = 0; i < m_cursor; ++i)
    {
      if (m_cache_entries[i].m_lsa == start_postpone_lsa)
    {
      // Found start lsa
      start_index = (int) i;
      break;
    }
    }

  if (start_index < 0)
    {
      // Start LSA was not found. Unexpected situation
      return false;
    }

  const size_t RCV_DATA_DEFAULT_SIZE = 1024;
  cubmem::extensible_stack_block<RCV_DATA_DEFAULT_SIZE> rcv_data_buffer { cubmem::PRIVATE_BLOCK_ALLOCATOR };

  // Run all postpones after start_index
  for (std::size_t i = start_index; i < m_cursor; ++i)
    {
      cache_entry &entry = m_cache_entries[i];

      // Get redo data header
      char *redo_data = m_redo_data_buf.get_ptr () + entry.m_offset;
      log_rec_redo redo = * (log_rec_redo *) redo_data;

      // Get recovery data
      char *data_ptr = redo_data + sizeof (log_rec_redo);
      data_ptr = PTR_ALIGN (data_ptr, MAX_ALIGNMENT);
      rcv_data_buffer.extend_to (redo.length);
      std::memcpy (rcv_data_buffer.get_ptr (), data_ptr, redo.length);

      (void) log_execute_run_postpone (&thread_ref, &entry.m_lsa, &redo, rcv_data_buffer.get_ptr ());
    }

  // Finished running postpones, update the number of entries which should be run on next commit
  assert (!m_is_redo_data_buf_full);
  m_cursor = start_index;
  m_redo_data_offset = m_cache_entries[start_index].m_offset;
  if (m_cursor == 0)
    {
      assert (m_redo_data_offset == 0); // should be 0 when cursor is back to 0
      reset ();
    }

  return true;
}

bool
log_postpone_cache::is_full () const
{
  return m_cursor == MAX_CACHE_ENTRIES || m_is_redo_data_buf_full;
}