sql_get_diagnostics.h

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/* Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.

   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 SQL_GET_DIAGNOSTICS_H
#define SQL_GET_DIAGNOSTICS_H

#include "my_dbug.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) {}

  virtual enum_sql_command sql_command_code() const {
    return SQLCOM_GET_DIAGNOSTICS;
  }

  virtual bool execute(THD *thd);

 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() { DBUG_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() { DBUG_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);

 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);

 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