monitor_transaction.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.
 *
 */

//
// monitor_transaction.cpp - implementation of transaction statistics management
//

#include "monitor_transaction.hpp"

#include "log_impl.h"
#include "system_parameter.h"

#include <cassert>

namespace cubmonitor
{
  // transaction_sheet_manager

  // static members
  std::size_t transaction_sheet_manager::s_current_sheet_count = 0;
  unsigned transaction_sheet_manager::s_sheet_start_count[MAX_SHEETS] = { 0 };
  std::size_t transaction_sheet_manager::s_transaction_count = 0;
  transaction_sheet *transaction_sheet_manager::s_transaction_sheets = NULL;
  std::mutex transaction_sheet_manager::s_sheets_mutex = {};

  void
  transaction_sheet_manager::static_init (void)
  {
    // note - should be protected by mutex

    if (s_transaction_sheets == NULL)
      {
    // get transaction count
    std::size_t tran_count = NUM_NORMAL_TRANS;

    // all transaction start with invalid sheets
    s_transaction_sheets = new transaction_sheet[tran_count];

    for (std::size_t it = 0; it < tran_count; it++)
      {
        s_transaction_sheets[it] = INVALID_TRANSACTION_SHEET;
      }
    s_transaction_count = tran_count;
      }
    else
      {
    // already initialized
      }
  }

  bool
  transaction_sheet_manager::start_watch (void)
  {
    std::unique_lock<std::mutex> ulock (s_sheets_mutex);

    // make sure it is initialized
    static_init ();

    // get current transaction
    int transaction = logtb_get_current_tran_index ();

    if (transaction <= LOG_SYSTEM_TRAN_INDEX || transaction >= (int) s_transaction_count)
      {
    // invalid transaction
    assert (false);
    return false;
      }

    std::size_t tran_array_index = std::size_t (transaction - 1);
    if (s_transaction_sheets[tran_array_index] == INVALID_TRANSACTION_SHEET)
      {
    // transaction doesn't have a sheet assigned
    // find unused sheet
    if (s_current_sheet_count >= MAX_SHEETS)
      {
        // already maxed
        return false;
      }

    // iterate sheets. must have counter 0 if unused
    for (std::size_t sheet_index = 0; sheet_index < MAX_SHEETS; sheet_index++)
      {
        if (s_sheet_start_count[sheet_index] == 0)
          {
        // found free sheet; assign to current transaction
        s_transaction_sheets[tran_array_index] = sheet_index;
        s_sheet_start_count[sheet_index] = 1;

        // increment used sheets count
        ++s_current_sheet_count;
        return true;
          }
      }

    assert (false);
    return false;
      }
    else
      {
    // already have a sheet; increment its count
    assert (s_sheet_start_count[s_transaction_sheets[tran_array_index]] > 0);

    ++s_sheet_start_count[s_transaction_sheets[tran_array_index]];
    return true;
      }
  }

  void
  transaction_sheet_manager::end_watch (bool end_all /* = false */)
  {
    std::unique_lock<std::mutex> ulock (s_sheets_mutex);

    // make sure it is initialized
    static_init ();

    // get current transaction
    int transaction = logtb_get_current_tran_index ();

    if (transaction <= LOG_SYSTEM_TRAN_INDEX || transaction >= (int) s_transaction_count)
      {
    // invalid transaction
    assert (false);
    return;
      }

    std::size_t index = transaction - 1;
    if (s_transaction_sheets[index] == INVALID_TRANSACTION_SHEET)
      {
    // no sheet open... might have been cleared
    return;
      }

    transaction_sheet sheet = s_transaction_sheets[index];
    if (s_sheet_start_count[sheet] == 0)
      {
    // this is an invalid state
    assert (false);
    return;
      }

    if (end_all)
      {
    // end all
    s_sheet_start_count[sheet] = 0;
      }
    else
      {
    // end once
    --s_sheet_start_count[sheet];
      }

    if (s_sheet_start_count[sheet] == 0)
      {
    // sheet is now free
    s_transaction_sheets[index] = INVALID_TRANSACTION_SHEET;
    --s_current_sheet_count;
      }
  }

  transaction_sheet
  transaction_sheet_manager::get_sheet (void)
  {
    if (s_current_sheet_count == 0)
      {
    // no sheets; early out
    return INVALID_TRANSACTION_SHEET;
      }

    assert (s_transaction_sheets != NULL && s_transaction_count > 0);

    int transaction = logtb_get_current_tran_index ();

    if (transaction <= LOG_SYSTEM_TRAN_INDEX || transaction >= (int) s_transaction_count)
      {
    // invalid transaction; may be a daemon or vacuum worker
    return INVALID_TRANSACTION_SHEET;
      }

    // return transaction's sheets if open or invalid sheet
    return s_transaction_sheets[transaction - 1];
  }

} // namespace cubmonitor