mariadb/storage/perfschema/table_uvar_by_thread.h

/* Copyright (c) 2013, 2023, Oracle and/or its affiliates.

  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 */

#ifndef TABLE_UVAR_BY_THREAD_H
#define TABLE_UVAR_BY_THREAD_H

/**
  @file storage/perfschema/table_uvar_by_thread.h
  Table USER_VARIABLES_BY_THREAD (declarations).
*/

#include "pfs_column_types.h"
#include "pfs_engine_table.h"
#include "pfs_instr_class.h"
#include "pfs_instr.h"
#include "table_helper.h"

/**
  @addtogroup Performance_schema_tables
  @{
*/

struct User_variable
{
public:
  User_variable()
  {}

  User_variable(const User_variable& uv)
    : m_name(uv.m_name), m_value(uv.m_value)
  {}

  ~User_variable()
  {}

  PFS_variable_name_row m_name;
  PFS_user_variable_value_row m_value;
};

class User_variables
{
  typedef Dynamic_array<User_variable> User_variable_array;

public:
  User_variables()
    : m_pfs(NULL), m_thread_internal_id(0), m_array(PSI_INSTRUMENT_MEM)
  {
  }

  void reset()
  {
    m_pfs= NULL;
    m_thread_internal_id= 0;
    for (uint i=0; i < m_array.elements(); i++)
      m_array.at(i).~User_variable();
    m_array.clear();
  }

  void materialize(PFS_thread *pfs, THD *thd);

  bool is_materialized(PFS_thread *pfs)
  {
    assert(pfs != NULL);
    if (m_pfs != pfs)
      return false;
    if (m_thread_internal_id != pfs->m_thread_internal_id)
      return false;
    return true;
  }

  const User_variable *get(uint index) const
  {
    if (index >= m_array.elements())
      return NULL;

    const User_variable *p= & m_array.at(index);
    return p;
  }

private:
  PFS_thread *m_pfs;
  ulonglong m_thread_internal_id;
  User_variable_array m_array;
};

/**
  A row of table
  PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD.
*/
struct row_uvar_by_thread
{
  /** Column THREAD_ID. */
  ulonglong m_thread_internal_id;
  /** Column VARIABLE_NAME. */
  const PFS_variable_name_row *m_variable_name;
  /** Column VARIABLE_VALUE. */
  const PFS_user_variable_value_row *m_variable_value;
};

/**
  Position of a cursor on
  PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD.
  Index 1 on thread (0 based)
  Index 2 on user variable (0 based)
*/
struct pos_uvar_by_thread
: public PFS_double_index
{
  pos_uvar_by_thread()
    : PFS_double_index(0, 0)
  {}

  inline void reset(void)
  {
    m_index_1= 0;
    m_index_2= 0;
  }

  inline void next_thread(void)
  {
    m_index_1++;
    m_index_2= 0;
  }
};

/** Table PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD. */
class table_uvar_by_thread : public PFS_engine_table
{
  typedef pos_uvar_by_thread pos_t;

public:
  static PFS_engine_table_share_state m_share_state;
  /** Table share */
  static PFS_engine_table_share m_share;
  static PFS_engine_table* create();
  static ha_rows get_row_count();

  int rnd_next() override;
  int rnd_pos(const void *pos) override;
  void reset_position(void) override;

protected:
  int read_row_values(TABLE *table,
                      unsigned char *buf,
                      Field **fields,
                      bool read_all) override;

  table_uvar_by_thread();

public:
  ~table_uvar_by_thread()
  { m_THD_cache.reset(); }

protected:
  int materialize(PFS_thread *thread);
  void make_row(PFS_thread *thread, const User_variable *uvar);

private:
  /** Table share lock. */
  static THR_LOCK m_table_lock;
  /** Fields definition. */
  static TABLE_FIELD_DEF m_field_def;

  /** Current THD user variables. */
  User_variables m_THD_cache;
  /** Current row. */
  row_uvar_by_thread m_row;
  /** True is the current row exists. */
  bool m_row_exists;
  /** Current position. */
  pos_t m_pos;
  /** Next position. */
  pos_t m_next_pos;
};

/** @} */
#endif