table_session_variables.h

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/* Copyright (c) 2015, 2022, Oracle and/or its affiliates.
 
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  it under the terms of the GNU General Public License, version 2.0,
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef TABLE_SESSION_VARIABLES_H
#define TABLE_SESSION_VARIABLES_H
 
/**
  @file storage/perfschema/table_session_variables.h
  Table SESSION_VARIABLES (declarations).
*/
 
#include <sys/types.h>
 
#include "my_base.h"
#include "my_inttypes.h"
#include "storage/perfschema/pfs.h"
#include "storage/perfschema/pfs_engine_table.h"
#include "storage/perfschema/pfs_variable.h"
#include "storage/perfschema/table_helper.h"
 
class Field;
class Plugin_table;
struct TABLE;
struct THR_LOCK;
/**
  @addtogroup performance_schema_tables
  @{
*/
 
class PFS_index_session_variables : public PFS_engine_index {
 public:
  PFS_index_session_variables()
      : PFS_engine_index(&m_key), m_key("VARIABLE_NAME") {}
 
  ~PFS_index_session_variables() override = default;
 
  virtual bool match(const System_variable *pfs);
 
 private:
  PFS_key_variable_name m_key;
};
 
/**
  A row of table
  PERFORMANCE_SCHEMA.SESSION_VARIABLES.
*/
struct row_session_variables {
  /** Column VARIABLE_NAME. */
  PFS_variable_name_row m_variable_name;
  /** Column VARIABLE_VALUE. */
  PFS_variable_value_row m_variable_value;
};
 
/** Table PERFORMANCE_SCHEMA.SESSION_VARIABLES. */
class table_session_variables : public PFS_engine_table {
  typedef PFS_simple_index 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(void) override;
 
  int rnd_init(bool scan) 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_session_variables();
 
 public:
  ~table_session_variables() override = default;
 
 protected:
  int make_row(const System_variable *system_var);
 
 private:
  /** Table share lock. */
  static THR_LOCK m_table_lock;
  /** Table definition. */
  static Plugin_table m_table_def;
 
  /** Current THD variables. */
  PFS_system_variable_cache m_sysvar_cache;
  /** Current row. */
  row_session_variables m_row;
  /** Current position. */
  pos_t m_pos;
  /** Next position. */
  pos_t m_next_pos;
 
  PFS_index_session_variables *m_opened_index;
};
 
/** @} */
#endif