sql_get_diagnostics.h

/* Copyright (c) 2011, 2024, 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.

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   as designated in a particular file or component or in included license
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   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
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef SQL_GET_DIAGNOSTICS_H
#define SQL_GET_DIAGNOSTICS_H

#include <assert.h>

#include "my_sqlcommand.h"
#include "sql/sql_cmd.h"  // Sql_cmd

class Diagnostics_area;
class Diagnostics_information;
class Item;
class Sql_condition;
class String;
class THD;
template <class T>
class List;

/**
  Sql_cmd_get_diagnostics represents a GET DIAGNOSTICS statement.

  The GET DIAGNOSTICS statement retrieves exception or completion
  condition information from a Diagnostics Area, usually pertaining
  to the last non-diagnostic SQL statement that was executed.
*/
class Sql_cmd_get_diagnostics : public Sql_cmd {
 public:
  /**
    Constructor, used to represent a GET DIAGNOSTICS statement.

    @param info Diagnostics information to be obtained.
  */
  Sql_cmd_get_diagnostics(Diagnostics_information *info) : m_info(info) {}

  enum_sql_command sql_command_code() const override {
    return SQLCOM_GET_DIAGNOSTICS;
  }

  bool execute(THD *thd) override;

 private:
  /** The information to be obtained. */
  Diagnostics_information *m_info;
};

/**
  Represents the diagnostics information to be obtained.

  Diagnostic information is made available through statement
  information and condition information items.
*/
class Diagnostics_information {
 public:
  /**
    Which Diagnostics Area to access.
  */
  enum Which_area {
    /** Access the first Diagnostics Area. */
    CURRENT_AREA,
    /** Access the second Diagnostics Area. */
    STACKED_AREA
  };

  /** Set which Diagnostics Area to access. */
  void set_which_da(Which_area area) { m_area = area; }

  /** Get which Diagnostics Area to access. */
  Which_area get_which_da(void) const { return m_area; }

  /**
    Aggregate diagnostics information.

    @param thd  The current thread.
    @param da   The Diagnostics Area.

    @retval false on success.
    @retval true on error
  */
  virtual bool aggregate(THD *thd, const Diagnostics_area *da) = 0;

 protected:
  /**
    Diagnostics_information objects are allocated in thd->mem_root.
    Do not rely on the destructor for any cleanup.
  */
  virtual ~Diagnostics_information() { assert(false); }

  /**
    Evaluate a diagnostics information item in a specific context.

    @param thd        The current thread.
    @param diag_item  The diagnostics information item.
    @param ctx        The context to evaluate the item.

    @retval false on success.
    @retval true on error.
  */
  template <typename Diag_item, typename Context>
  bool evaluate(THD *thd, Diag_item *diag_item, Context ctx) {
    Item *value;

    /* Get this item's value. */
    if (!(value = diag_item->get_value(thd, ctx))) return true;

    /* Set variable/parameter value. */
    return diag_item->set_value(thd, &value);
  }

 private:
  /** Which Diagnostics Area to access. */
  Which_area m_area;
};

/**
  A diagnostics information item. Used to associate a specific
  diagnostics information item to a target variable.
*/
class Diagnostics_information_item {
 public:
  /**
    Set a value for this item.

    @param thd    The current thread.
    @param value  The obtained value.

    @retval false on success.
    @retval true on error.
  */
  bool set_value(THD *thd, Item **value);

 protected:
  /**
    Constructor, used to represent a diagnostics information item.

    @param target A target that gets the value of this item.
  */
  Diagnostics_information_item(Item *target) : m_target(target) {}

  /**
    Diagnostics_information_item objects are allocated in thd->mem_root.
    Do not rely on the destructor for any cleanup.
  */
  virtual ~Diagnostics_information_item() { assert(false); }

 private:
  /** The target variable that will receive the value of this item. */
  Item *m_target;
};

/**
  A statement information item.
*/
class Statement_information_item : public Diagnostics_information_item {
 public:
  /** The name of a statement information item. */
  enum Name { NUMBER, ROW_COUNT };

  /**
    Constructor, used to represent a statement information item.

    @param name   The name of this item.
    @param target A target that gets the value of this item.
  */
  Statement_information_item(Name name, Item *target)
      : Diagnostics_information_item(target), m_name(name) {}

  /** Obtain value of this statement information item. */
  Item *get_value(THD *thd, const Diagnostics_area *da);

 private:
  /** The name of this statement information item. */
  Name m_name;
};

/**
  Statement information.

  @remark Provides information about the execution of a statement.
*/
class Statement_information : public Diagnostics_information {
 public:
  /**
    Constructor, used to represent the statement information of a
    GET DIAGNOSTICS statement.

    @param items  List of requested statement information items.
  */
  Statement_information(List<Statement_information_item> *items)
      : m_items(items) {}

  /** Obtain statement information in the context of a Diagnostics Area. */
  bool aggregate(THD *thd, const Diagnostics_area *da) override;

 private:
  /* List of statement information items. */
  List<Statement_information_item> *m_items;
};

/**
  A condition information item.
*/
class Condition_information_item : public Diagnostics_information_item {
 public:
  /**
    The name of a condition information item.
  */
  enum Name {
    CLASS_ORIGIN,
    SUBCLASS_ORIGIN,
    CONSTRAINT_CATALOG,
    CONSTRAINT_SCHEMA,
    CONSTRAINT_NAME,
    CATALOG_NAME,
    SCHEMA_NAME,
    TABLE_NAME,
    COLUMN_NAME,
    CURSOR_NAME,
    MESSAGE_TEXT,
    MYSQL_ERRNO,
    RETURNED_SQLSTATE
  };

  /**
    Constructor, used to represent a condition information item.

    @param name   The name of this item.
    @param target A target that gets the value of this item.
  */
  Condition_information_item(Name name, Item *target)
      : Diagnostics_information_item(target), m_name(name) {}

  /** Obtain value of this condition information item. */
  Item *get_value(THD *thd, const Sql_condition *cond);

 private:
  /** The name of this condition information item. */
  Name m_name;

  /** Create an string item to represent a condition item string. */
  Item *make_utf8_string_item(THD *thd, const String *str);
};

/**
  Condition information.

  @remark Provides information about conditions raised during the
          execution of a statement.
*/
class Condition_information : public Diagnostics_information {
 public:
  /**
    Constructor, used to represent the condition information of a
    GET DIAGNOSTICS statement.

    @param cond_number_expr Number that identifies the diagnostic condition.
    @param items List of requested condition information items.
  */
  Condition_information(Item *cond_number_expr,
                        List<Condition_information_item> *items)
      : m_cond_number_expr(cond_number_expr), m_items(items) {}

  /** Obtain condition information in the context of a Diagnostics Area. */
  bool aggregate(THD *thd, const Diagnostics_area *da) override;

 private:
  /**
    Number that identifies the diagnostic condition for which
    information is to be obtained.
  */
  Item *m_cond_number_expr;

  /** List of condition information items. */
  List<Condition_information_item> *m_items;
};

#endif