trigger_chain.cc

/*
   Copyright (c) 2013, 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.

   This program is designed to work 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 either included with
   the program or referenced in the documentation.

   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
*/

#include "sql/trigger_chain.h"

#include <assert.h>

#include "my_inttypes.h"
#include "my_sys.h"
#include "mysql/strings/m_ctype.h"
#include "mysqld_error.h"          // ER_*
#include "sql/dd/types/trigger.h"  // name_collation
#include "sql/mysqld.h"            // table_alias_charset
#include "sql/sp_head.h"           // sp_head
#include "sql/trigger.h"           // Trigger

struct MEM_ROOT;

Trigger_chain::~Trigger_chain() { m_triggers.destroy_elements(); }

/**
  Add a new trigger into the list of triggers with the same
  ACTION/TIMING value combination. This method is called during
  handling of statement CREATE TRIGGER.

  @param mem_root                 memory root for allocations
  @param new_trigger              pointer to the Trigger to add into the list
  @param ordering_clause          trigger ordering clause (FOLLOWS/PRECEDES)
  @param referenced_trigger_name  trigger name referenced by clause
                                  FOLLOWS/PRECEDES in the CREATE TRIGGER
                                  statement

  @return Operation status.
    @retval false Success.
    @retval true  Failure: either trigger not found or OOM. Set error in
    Diagnostic_area in case when trigger not found.
*/

bool Trigger_chain::add_trigger(MEM_ROOT *mem_root, Trigger *new_trigger,
                                enum_trigger_order_type ordering_clause,
                                const LEX_CSTRING &referenced_trigger_name) {
  switch (ordering_clause) {
    case TRG_ORDER_NONE:
      return add_trigger(mem_root, new_trigger);

    case TRG_ORDER_FOLLOWS:
    case TRG_ORDER_PRECEDES: {
      assert(referenced_trigger_name.str);

      List_iterator<Trigger> it(m_triggers);
      List_iterator<Trigger> it2 = it;

      while (true) {
        Trigger *t = it2++;

        if (!t) {
          my_error(ER_REFERENCED_TRG_DOES_NOT_EXIST, MYF(0),
                   referenced_trigger_name.str);
          return true;
        }

        if (!my_strnncoll(
                dd::Trigger::name_collation(),
                pointer_cast<const uchar *>(t->get_trigger_name().str),
                t->get_trigger_name().length,
                pointer_cast<const uchar *>(referenced_trigger_name.str),
                referenced_trigger_name.length))
          break;

        it = it2;
      }

      if (ordering_clause == TRG_ORDER_FOLLOWS) it = it2;

      bool rc;

      if (it.is_before_first())
        rc = m_triggers.push_front(new_trigger, mem_root);
      else
        rc = it.after(new_trigger, mem_root);

      return rc;
    }
  }

  assert(false);
  return true;
}

/**
  Add a new trigger into the list of triggers with the same
  ACTION/TIMING value combination. This method is called when a trigger
  is loaded from Data Dictionary.

  @param mem_root        memory root for allocations
  @param new_trigger     pointer to the Trigger to add into the list

  @return Operation status.
    @retval false Success.
    @retval true  Failure.
*/

bool Trigger_chain::add_trigger(MEM_ROOT *mem_root, Trigger *new_trigger) {
  return m_triggers.push_back(new_trigger, mem_root);
}

/**
  Run every trigger in the list of triggers.

  @param thd  Thread context
  @return  Result of trigger execution
    @retval false  all triggers in the list were executed successfully.
    @retval true   some trigger was failed. We stop triggers execution
                   on the first failed trigger and don't attempt to finish
                   the rest of triggers located after the failed one.
*/

bool Trigger_chain::execute_triggers(THD *thd) {
  List_iterator_fast<Trigger> it(m_triggers);
  Trigger *t;

  while ((t = it++)) {
    if (t->execute(thd)) return true;
  }

  return false;
}

/**
  Iterate over the list of triggers and add tables and routines used by trigger
  to the set of elements used by statement.

  @param [in]     thd               thread context
  @param [in,out] prelocking_ctx    prelocking context of the statement
  @param [in]     table_list        Table_ref for the table
*/

void Trigger_chain::add_tables_and_routines(THD *thd,
                                            Query_tables_list *prelocking_ctx,
                                            Table_ref *table_list) {
  List_iterator_fast<Trigger> it(m_triggers);
  Trigger *t;

  while ((t = it++))
    t->add_tables_and_routines(thd, prelocking_ctx, table_list);
}

/**
  Iterate over the list of triggers and mark fields of subject table
  which we read/set in every trigger.

  @param [in] subject_table trigger subject table
*/

void Trigger_chain::mark_fields(TABLE *subject_table) {
  List_iterator_fast<Trigger> it(m_triggers);
  Trigger *t;

  while ((t = it++)) t->get_sp()->mark_used_trigger_fields(subject_table);
}

/**
  Iterate over the list of triggers and check whether some
  table's fields are used in any trigger.

  @param [in] used_fields       bitmap of fields to check

  @return Check result
    @retval true   Some table fields are used in trigger
    @retval false  None of table fields are used in trigger
*/

bool Trigger_chain::has_updated_trigger_fields(const MY_BITMAP *used_fields) {
  List_iterator_fast<Trigger> it(m_triggers);
  Trigger *t;

  while ((t = it++)) {
    // Even if one trigger is unparsable, the whole thing is not usable.

    if (t->has_parse_error()) return false;

    if (t->get_sp()->has_updated_trigger_fields(used_fields)) return true;
  }

  return false;
}