table_trigger_dispatcher.h

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/*
   Copyright (c) 2013, 2025, 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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   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_TRIGGER_DISPATCHER_H_INCLUDED
#define TABLE_TRIGGER_DISPATCHER_H_INCLUDED
 
///////////////////////////////////////////////////////////////////////////
 
#include <assert.h>
#include <string.h>
 
#include "lex_string.h"
#include "my_inttypes.h"
#include "my_sys.h"
#include "mysql_com.h"                        // MYSQL_ERRMSG_SIZE
#include "mysqld_error.h"                     // ER_PARSE_ERROR
#include "sql/table_trigger_field_support.h"  // Table_trigger_field_support
#include "sql/trigger_def.h"                  // enum_trigger_action_time_type
 
class Field;
class Query_tables_list;
class String;
class THD;
class Trigger;
class Trigger_chain;
struct MEM_ROOT;
 
namespace dd {
class Table;
}  // namespace dd
struct TABLE;
class Table_ref;
template <class T>
class List;
 
///////////////////////////////////////////////////////////////////////////
 
/**
  This class holds all information about triggers of a table.
*/
 
class Table_trigger_dispatcher : public Table_trigger_field_support {
 public:
  static Table_trigger_dispatcher *create(TABLE *subject_table);
 
  bool check_n_load(THD *thd, const dd::Table &table);
 
  /*
   During upgrade from 5.7, we need to use the trigger chains to fix
   the trigger order.
  */
  bool reorder_57_list(MEM_ROOT *mem_root, List<Trigger> *triggers);
 
 private:
  Table_trigger_dispatcher(TABLE *subject_table);
 
 public:
  ~Table_trigger_dispatcher() override;
 
  /**
    Checks if there is a broken trigger for this table.
 
    @retval false if all triggers are Ok.
    @retval true in case there is at least one broken trigger (a trigger which
    SQL-definition can not be parsed) for this table.
  */
  bool check_for_broken_triggers() {
    if (m_has_unparseable_trigger) {
      my_message(ER_PARSE_ERROR, m_parse_error_message, MYF(0));
      return true;
    }
    return false;
  }
 
  /**
    Create trigger for table.
 
    @param      thd   Thread context
    @param[out] binlog_create_trigger_stmt
                      Well-formed CREATE TRIGGER statement for putting into
    binlog (after successful execution)
    @param      if_not_exists
                      True if 'IF NOT EXISTS' clause was specified
    @param[out] already_exists
                      Set to true if trigger already exists on the same table
 
    @note
      - Assumes that trigger name is fully qualified.
      - NULL-string means the following LEX_STRING instance:
      { str = 0; length = 0 }.
      - In other words, definer_user and definer_host should contain
      simultaneously NULL-strings (non-SUID/old trigger) or valid strings
      (SUID/new trigger).
 
    @return Operation status.
      @retval false Success
      @retval true  Failure
  */
  bool create_trigger(THD *thd, String *binlog_create_trigger_stmt,
                      bool if_not_exists, bool &already_exists);
 
  bool process_triggers(THD *thd, enum_trigger_event_type event,
                        enum_trigger_action_time_type action_time,
                        bool old_row_is_record1);
 
  Trigger_chain *get_triggers(int event, int action_time) {
    assert(0 <= event && event < TRG_EVENT_MAX);
    assert(0 <= action_time && action_time < TRG_ACTION_MAX);
    return m_trigger_map[event][action_time];
  }
 
  const Trigger_chain *get_triggers(int event, int action_time) const {
    assert(0 <= event && event < TRG_EVENT_MAX);
    assert(0 <= action_time && action_time < TRG_ACTION_MAX);
    return m_trigger_map[event][action_time];
  }
 
  Trigger *find_trigger(const LEX_STRING &trigger_name);
 
  bool has_triggers(enum_trigger_event_type event,
                    enum_trigger_action_time_type action_time) const {
    return get_triggers(event, action_time) != nullptr;
  }
 
  bool has_update_triggers() const {
    return get_triggers(TRG_EVENT_UPDATE, TRG_ACTION_BEFORE) ||
           get_triggers(TRG_EVENT_UPDATE, TRG_ACTION_AFTER);
  }
 
  bool has_delete_triggers() const {
    return get_triggers(TRG_EVENT_DELETE, TRG_ACTION_BEFORE) ||
           get_triggers(TRG_EVENT_DELETE, TRG_ACTION_AFTER);
  }
 
  bool mark_fields(enum_trigger_event_type event);
 
  bool add_tables_and_routines_for_triggers(THD *thd,
                                            Query_tables_list *prelocking_ctx,
                                            Table_ref *table_list);
 
  void enable_fields_temporary_nullability(THD *thd);
  void disable_fields_temporary_nullability();
  void reset_field_nulls();
 
  void print_upgrade_warnings(THD *thd);
 
  void parse_triggers(THD *thd, List<Trigger> *triggers, bool is_upgrade);
 
 private:
  Trigger_chain *create_trigger_chain(
      MEM_ROOT *mem_root, enum_trigger_event_type event,
      enum_trigger_action_time_type action_time);
 
  bool prepare_record1_accessors();
 
  /**
    Remember a parse error that occurred while parsing trigger definitions
    loaded from the Data Dictionary. This makes the Table_trigger_dispatcher
    enter the error state flagged by m_has_unparseable_trigger == true. The
    error message will be used whenever a statement invoking or manipulating
    triggers is issued against the Table_trigger_dispatcher's table.
 
    @param error_message The error message thrown by the parser.
  */
  void set_parse_error_message(const char *error_message) {
    if (!m_has_unparseable_trigger) {
      m_has_unparseable_trigger = true;
      snprintf(m_parse_error_message, sizeof(m_parse_error_message), "%s",
               error_message);
    }
  }
 
 private:
  /************************************************************************
   * Table_trigger_field_support interface implementation.
   ***********************************************************************/
 
  TABLE *get_subject_table() override { return m_subject_table; }
 
  Field *get_trigger_variable_field(enum_trigger_variable_type v,
                                    int field_index) override {
    return (v == TRG_OLD_ROW) ? m_old_field[field_index]
                              : m_new_field[field_index];
  }
 
 private:
  /**
    TABLE instance for which this triggers list object was created.
  */
  TABLE *m_subject_table;
 
  /// Triggers grouped by event, action_time.
  Trigger_chain *m_trigger_map[TRG_EVENT_MAX][TRG_ACTION_MAX];
 
  /**
    Copy of TABLE::Field array with field pointers set to TABLE::record[1]
    buffer instead of TABLE::record[0] (used for OLD values in on UPDATE
    trigger and DELETE trigger when it is called for REPLACE).
  */
  Field **m_record1_field;
 
  /**
    During execution of trigger m_new_field and m_old_field should point to the
    array of fields representing new or old version of row correspondingly
    (so it can point to TABLE::field or to
    Table_trigger_dispatcher::m_record1_field).
  */
  Field **m_new_field;
  Field **m_old_field;
 
  /**
    This flag indicates that one of the triggers was not parsed successfully,
    and as a precaution the object has entered the state where all trigger
    operations result in errors until all the table triggers are dropped. It is
    not safe to add triggers since it is unknown if the broken trigger has the
    same name or event type. Nor is it safe to invoke any trigger. The only
    safe operations are drop_trigger() and drop_all_triggers().
 
    We can't use the value of m_parse_error_message as a flag to inform that
    a trigger has a parse error since for multi-byte locale the first byte of
    message can be 0 but the message still be meaningful. It means that just a
    comparison against m_parse_error_message[0] can not be done safely.
 
    @see Table_trigger_dispatcher::set_parse_error()
  */
  bool m_has_unparseable_trigger;
 
  /**
    This error will be displayed when the user tries to manipulate or invoke
    triggers on a table that has broken triggers. It is set once per statement
    and thus will contain the first parse error encountered in the trigger file.
   */
  char m_parse_error_message[MYSQL_ERRMSG_SIZE];
};
 
///////////////////////////////////////////////////////////////////////////
 
#endif  // TABLE_TRIGGER_DISPATCHER_H_INCLUDED