table_uvar_by_thread.h

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/* Copyright (c) 2013, 2025, Oracle and/or its affiliates.
 
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  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  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
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  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 <assert.h>
#include <stddef.h>
#include <sys/types.h>
 
#include "my_base.h"
 
#include "my_inttypes.h"
#include "mysql/components/services/bits/psi_bits.h"
#include "prealloced_array.h"
#include "storage/perfschema/pfs_engine_table.h"
#include "storage/perfschema/pfs_instr.h"
#include "storage/perfschema/table_helper.h"
 
class Field;
class Plugin_table;
class THD;
struct TABLE;
struct THR_LOCK;
 
/**
  @addtogroup performance_schema_tables
  @{
*/
 
struct User_variable {
 public:
  User_variable() = default;
 
  User_variable(const User_variable &uv) = default;
 
  ~User_variable() = default;
 
  PFS_variable_name_row m_name;
  PFS_user_variable_value_row m_value;
};
 
class User_variables {
  typedef Prealloced_array<User_variable, 100> User_variable_array;
 
 public:
  User_variables()
      : m_pfs(nullptr), m_thread_internal_id(0), m_array(PSI_INSTRUMENT_ME) {}
 
  void reset() {
    m_pfs = nullptr;
    m_thread_internal_id = 0;
    m_array.clear();
  }
 
  void materialize(PFS_thread *pfs, THD *thd);
 
  bool is_materialized(PFS_thread *pfs) {
    assert(pfs != nullptr);
    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.size()) {
      return nullptr;
    }
 
    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() {
    m_index_1 = 0;
    m_index_2 = 0;
  }
 
  inline void next_thread() {
    m_index_1++;
    m_index_2 = 0;
  }
};
 
class PFS_index_uvar_by_thread : public PFS_engine_index {
 public:
  PFS_index_uvar_by_thread()
      : PFS_engine_index(&m_key_1, &m_key_2),
        m_key_1("THREAD_ID"),
        m_key_2("VARIABLE_NAME") {}
 
  ~PFS_index_uvar_by_thread() override = default;
 
  virtual bool match(PFS_thread *pfs);
  virtual bool match(const User_variable *pfs);
 
 private:
  PFS_key_thread_id m_key_1;
  PFS_key_variable_name m_key_2;
};
 
/** Table PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD. */
class table_uvar_by_thread : public PFS_engine_table {
  typedef pos_uvar_by_thread pos_t;
 
 public:
  /** Table share */
  static PFS_engine_table_share m_share;
  static PFS_engine_table *create(PFS_engine_table_share *);
  static ha_rows get_row_count();
 
  void reset_position() override;
 
  int rnd_next() override;
  int rnd_pos(const void *pos) override;
 
  int index_init(uint idx, bool sorted) override;
  int index_next() 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() override { m_THD_cache.reset(); }
 
 protected:
  int materialize(PFS_thread *thread);
  int make_row(PFS_thread *thread, const User_variable *uvar);
 
 private:
  /** Table share lock. */
  static THR_LOCK m_table_lock;
  /** Table definition. */
  static Plugin_table m_table_def;
 
  /** Current THD user variables. */
  User_variables m_THD_cache;
  /** Current row. */
  row_uvar_by_thread m_row;
  /** Current position. */
  pos_t m_pos;
  /** Next position. */
  pos_t m_next_pos;
 
  PFS_index_uvar_by_thread *m_opened_index;
};
 
/** @} */
#endif