sql_class.cc

/*
   Copyright (c) 2000, 2013, 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 as published by
   the Free Software Foundation; version 2 of the License.

   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 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
*/


/*****************************************************************************
**
** This file implements classes defined in sql_class.h
** Especially the classes to handle a result from a select
**
*****************************************************************************/

#include "my_global.h"                          /* NO_EMBEDDED_ACCESS_CHECKS */
#include "binlog.h"
#include "sql_priv.h"
#include "unireg.h"                    // REQUIRED: for other includes
#include "sql_class.h"
#include "sql_cache.h"                          // query_cache_abort
#include "sql_base.h"                           // close_thread_tables
#include "sql_time.h"                         // date_time_format_copy
#include "sql_acl.h"                          // NO_ACCESS,
                                              // acl_getroot_no_password
#include "sql_base.h"                         // close_temporary_tables
#include "sql_handler.h"                      // mysql_ha_cleanup
#include "rpl_rli.h"
#include "rpl_filter.h"
#include "rpl_record.h"
#include "rpl_slave.h"
#include <my_bitmap.h>
#include "log_event.h"
#include "sql_audit.h"
#include <m_ctype.h>
#include <sys/stat.h>
#include <thr_alarm.h>
#ifdef  __WIN__
#include <io.h>
#endif
#include <mysys_err.h>
#include <limits.h>

#include "sp_rcontext.h"
#include "sp_cache.h"
#include "transaction.h"
#include "debug_sync.h"
#include "sql_parse.h"                          // is_update_query
#include "sql_callback.h"
#include "lock.h"
#include "global_threads.h"
#include "mysqld.h"

#include <mysql/psi/mysql_statement.h>

using std::min;
using std::max;

/*
  The following is used to initialise Table_ident with a internal
  table name
*/
char internal_table_name[2]= "*";
char empty_c_string[1]= {0};    /* used for not defined db */

LEX_STRING EMPTY_STR= { (char *) "", 0 };
LEX_STRING NULL_STR=  { NULL, 0 };

const char * const THD::DEFAULT_WHERE= "field list";

/****************************************************************************
** User variables
****************************************************************************/

extern "C" uchar *get_var_key(user_var_entry *entry, size_t *length,
                              my_bool not_used __attribute__((unused)))
{
  *length= entry->entry_name.length();
  return (uchar*) entry->entry_name.ptr();
}

extern "C" void free_user_var(user_var_entry *entry)
{
  entry->destroy();
}

bool Key_part_spec::operator==(const Key_part_spec& other) const
{
  return length == other.length &&
         !my_strcasecmp(system_charset_info, field_name.str,
                        other.field_name.str);
}

Key::Key(const Key &rhs, MEM_ROOT *mem_root)
  :type(rhs.type),
  key_create_info(rhs.key_create_info),
  columns(rhs.columns, mem_root),
  name(rhs.name),
  generated(rhs.generated)
{
  list_copy_and_replace_each_value(columns, mem_root);
}

Foreign_key::Foreign_key(const Foreign_key &rhs, MEM_ROOT *mem_root)
  :Key(rhs, mem_root),
  ref_db(rhs.ref_db),
  ref_table(rhs.ref_table),
  ref_columns(rhs.ref_columns, mem_root),
  delete_opt(rhs.delete_opt),
  update_opt(rhs.update_opt),
  match_opt(rhs.match_opt)
{
  list_copy_and_replace_each_value(ref_columns, mem_root);
}

/*
  Test if a foreign key (= generated key) is a prefix of the given key
  (ignoring key name, key type and order of columns)

  NOTES:
    This is only used to test if an index for a FOREIGN KEY exists

  IMPLEMENTATION
    We only compare field names

  RETURN
    0   Generated key is a prefix of other key
    1   Not equal
*/

bool foreign_key_prefix(Key *a, Key *b)
{
  /* Ensure that 'a' is the generated key */
  if (a->generated)
  {
    if (b->generated && a->columns.elements > b->columns.elements)
      swap_variables(Key*, a, b);               // Put shorter key in 'a'
  }
  else
  {
    if (!b->generated)
      return TRUE;                              // No foreign key
    swap_variables(Key*, a, b);                 // Put generated key in 'a'
  }

  /* Test if 'a' is a prefix of 'b' */
  if (a->columns.elements > b->columns.elements)
    return TRUE;                                // Can't be prefix

  List_iterator<Key_part_spec> col_it1(a->columns);
  List_iterator<Key_part_spec> col_it2(b->columns);
  const Key_part_spec *col1, *col2;

#ifdef ENABLE_WHEN_INNODB_CAN_HANDLE_SWAPED_FOREIGN_KEY_COLUMNS
  while ((col1= col_it1++))
  {
    bool found= 0;
    col_it2.rewind();
    while ((col2= col_it2++))
    {
      if (*col1 == *col2)
      {
        found= TRUE;
        break;
      }
    }
    if (!found)
      return TRUE;                              // Error
  }
  return FALSE;                                 // Is prefix
#else
  while ((col1= col_it1++))
  {
    col2= col_it2++;
    if (!(*col1 == *col2))
      return TRUE;
  }
  return FALSE;                                 // Is prefix
#endif
}


/****************************************************************************
** Thread specific functions
****************************************************************************/

void *thd_get_scheduler_data(THD *thd)
{
  return thd->scheduler.data;
}

void thd_set_scheduler_data(THD *thd, void *data)
{
  thd->scheduler.data= data;
}

PSI_thread *thd_get_psi(THD *thd)
{
  return thd->scheduler.m_psi;
}

ulong thd_get_net_wait_timeout(THD* thd)
{
  return thd->variables.net_wait_timeout;
}

void thd_set_psi(THD *thd, PSI_thread *psi)
{
  thd->scheduler.m_psi= psi;
}

void thd_set_killed(THD *thd)
{
  thd->killed= THD::KILL_CONNECTION;
}

void thd_clear_errors(THD *thd)
{
  my_errno= 0;
  thd->mysys_var->abort= 0;
}

void thd_set_thread_stack(THD *thd, char *stack_start)
{
  thd->thread_stack= stack_start;
}

void thd_lock_thread_count(THD *)
{
  mysql_mutex_lock(&LOCK_thread_count);
}

void thd_unlock_thread_count(THD *)
{
  mysql_cond_broadcast(&COND_thread_count);
  mysql_mutex_unlock(&LOCK_thread_count);
}

void thd_close_connection(THD *thd)
{
  if (thd->net.vio)
    vio_shutdown(thd->net.vio);
}

THD *thd_get_current_thd()
{
  return current_thd;
}

Thread_iterator thd_get_global_thread_list_begin()
{
  return global_thread_list_begin();
}
Thread_iterator thd_get_global_thread_list_end()
{
  return global_thread_list_end();
}

extern "C"
void thd_binlog_pos(const THD *thd,
                    const char **file_var,
                    unsigned long long *pos_var)
{
  thd->get_trans_pos(file_var, pos_var);
}

void thd_new_connection_setup(THD *thd, char *stack_start)
{
  DBUG_ENTER("thd_new_connection_setup");
  mysql_mutex_assert_owner(&LOCK_thread_count);
#ifdef HAVE_PSI_INTERFACE
  thd_set_psi(thd,
              PSI_THREAD_CALL(new_thread)
                (key_thread_one_connection, thd, thd->thread_id));
#endif
  thd->set_time();
  thd->prior_thr_create_utime= thd->thr_create_utime= thd->start_utime=
    my_micro_time();

  add_global_thread(thd);
  mysql_mutex_unlock(&LOCK_thread_count);

  DBUG_PRINT("info", ("init new connection. thd: 0x%lx fd: %d",
          (ulong)thd, mysql_socket_getfd(thd->net.vio->mysql_socket)));
  thd_set_thread_stack(thd, stack_start);
  DBUG_VOID_RETURN;
}

void thd_lock_data(THD *thd)
{
  mysql_mutex_lock(&thd->LOCK_thd_data);
}

void thd_unlock_data(THD *thd)
{
  mysql_mutex_unlock(&thd->LOCK_thd_data);
}

bool thd_is_transaction_active(THD *thd)
{
  return thd->transaction.is_active();
}

int thd_connection_has_data(THD *thd)
{
  Vio *vio= thd->net.vio;
  return vio->has_data(vio);
}

void thd_set_net_read_write(THD *thd, uint val)
{
  thd->net.reading_or_writing= val;
}

uint thd_get_net_read_write(THD *thd)
{
  return thd->net.reading_or_writing;
}

void thd_set_mysys_var(THD *thd, st_my_thread_var *mysys_var)
{
  thd->set_mysys_var(mysys_var);
}

my_socket thd_get_fd(THD *thd)
{
  return mysql_socket_getfd(thd->net.vio->mysql_socket);
}

int thd_store_globals(THD* thd)
{
  return thd->store_globals();
}

pthread_attr_t *get_connection_attrib(void)
{
  return &connection_attrib;
}

ulong get_max_connections(void)
{
  return max_connections;
}

/*
  The following functions form part of the C plugin API
*/

extern "C" int mysql_tmpfile(const char *prefix)
{
  char filename[FN_REFLEN];
  File fd = create_temp_file(filename, mysql_tmpdir, prefix,
#ifdef __WIN__
                             O_BINARY | O_TRUNC | O_SEQUENTIAL |
                             O_SHORT_LIVED |
#endif /* __WIN__ */
                             O_CREAT | O_EXCL | O_RDWR | O_TEMPORARY,
                             MYF(MY_WME));
  if (fd >= 0) {
#ifndef __WIN__
    /*
      This can be removed once the following bug is fixed:
      Bug #28903  create_temp_file() doesn't honor O_TEMPORARY option
                  (file not removed) (Unix)
    */
    unlink(filename);
#endif /* !__WIN__ */
  }

  return fd;
}


extern "C"
int thd_in_lock_tables(const THD *thd)
{
  return test(thd->in_lock_tables);
}


extern "C"
int thd_tablespace_op(const THD *thd)
{
  return test(thd->tablespace_op);
}


extern "C"
const char *set_thd_proc_info(void *thd_arg, const char *info,
                              const char *calling_function,
                              const char *calling_file,
                              const unsigned int calling_line)
{
  PSI_stage_info old_stage;
  PSI_stage_info new_stage;

  old_stage.m_key= 0;
  old_stage.m_name= info;

  set_thd_stage_info(thd_arg, & old_stage, & new_stage,
                     calling_function, calling_file, calling_line);

  return new_stage.m_name;
}

extern "C"
void set_thd_stage_info(void *opaque_thd,
                        const PSI_stage_info *new_stage,
                        PSI_stage_info *old_stage,
                        const char *calling_func,
                        const char *calling_file,
                        const unsigned int calling_line)
{
  THD *thd= (THD*) opaque_thd;
  if (thd == NULL)
    thd= current_thd;

  thd->enter_stage(new_stage, old_stage, calling_func, calling_file, calling_line);
}

void THD::enter_stage(const PSI_stage_info *new_stage,
                      PSI_stage_info *old_stage,
                      const char *calling_func,
                      const char *calling_file,
                      const unsigned int calling_line)
{
  DBUG_PRINT("THD::enter_stage", ("%s:%d", calling_file, calling_line));

  if (old_stage != NULL)
  {
    old_stage->m_key= m_current_stage_key;
    old_stage->m_name= proc_info;
  }

  if (new_stage != NULL)
  {
    const char *msg= new_stage->m_name;

#if defined(ENABLED_PROFILING)
    profiling.status_change(msg, calling_func, calling_file, calling_line);
#endif

    m_current_stage_key= new_stage->m_key;
    proc_info= msg;

    MYSQL_SET_STAGE(m_current_stage_key, calling_file, calling_line);
  }
  return;
}

extern "C"
void thd_enter_cond(MYSQL_THD thd, mysql_cond_t *cond, mysql_mutex_t *mutex,
                    const PSI_stage_info *stage, PSI_stage_info *old_stage)
{
  if (!thd)
    thd= current_thd;

  return thd->ENTER_COND(cond, mutex, stage, old_stage);
}

extern "C"
void thd_exit_cond(MYSQL_THD thd, const PSI_stage_info *stage)
{
  if (!thd)
    thd= current_thd;

  thd->EXIT_COND(stage);
  return;
}

extern "C"
void **thd_ha_data(const THD *thd, const struct handlerton *hton)
{
  return (void **) &thd->ha_data[hton->slot].ha_ptr;
}

extern "C"
void thd_storage_lock_wait(THD *thd, long long value)
{
  thd->utime_after_lock+= value;
}

extern "C"
void *thd_get_ha_data(const THD *thd, const struct handlerton *hton)
{
  return *thd_ha_data(thd, hton);
}


extern "C"
void thd_set_ha_data(THD *thd, const struct handlerton *hton,
                     const void *ha_data)
{
  plugin_ref *lock= &thd->ha_data[hton->slot].lock;
  if (ha_data && !*lock)
    *lock= ha_lock_engine(NULL, (handlerton*) hton);
  else if (!ha_data && *lock)
  {
    plugin_unlock(NULL, *lock);
    *lock= NULL;
  }
  *thd_ha_data(thd, hton)= (void*) ha_data;
}


extern "C"
long long thd_test_options(const THD *thd, long long test_options)
{
  return thd->variables.option_bits & test_options;
}

extern "C"
int thd_sql_command(const THD *thd)
{
  return (int) thd->lex->sql_command;
}

extern "C"
int thd_tx_isolation(const THD *thd)
{
  return (int) thd->tx_isolation;
}

extern "C"
int thd_tx_is_read_only(const THD *thd)
{
  return (int) thd->tx_read_only;
}

extern "C"
void thd_inc_row_count(THD *thd)
{
  thd->get_stmt_da()->inc_current_row_for_warning();
}


extern "C"
char *thd_security_context(THD *thd, char *buffer, unsigned int length,
                           unsigned int max_query_len)
{
  String str(buffer, length, &my_charset_latin1);
  Security_context *sctx= &thd->main_security_ctx;
  char header[256];
  int len;
  /*
    The pointers thd->query and thd->proc_info might change since they are
    being modified concurrently. This is acceptable for proc_info since its
    values doesn't have to very accurate and the memory it points to is static,
    but we need to attempt a snapshot on the pointer values to avoid using NULL
    values. The pointer to thd->query however, doesn't point to static memory
    and has to be protected by LOCK_thread_count or risk pointing to
    uninitialized memory.
  */
  const char *proc_info= thd->proc_info;

  len= my_snprintf(header, sizeof(header),
                   "MySQL thread id %lu, OS thread handle 0x%lx, query id %lu",
                   thd->thread_id, (ulong) thd->real_id, (ulong) thd->query_id);
  str.length(0);
  str.append(header, len);

  if (sctx->get_host()->length())
  {
    str.append(' ');
    str.append(sctx->get_host()->ptr());
  }

  if (sctx->get_ip()->length())
  {
    str.append(' ');
    str.append(sctx->get_ip()->ptr());
  }

  if (sctx->user)
  {
    str.append(' ');
    str.append(sctx->user);
  }

  if (proc_info)
  {
    str.append(' ');
    str.append(proc_info);
  }

  mysql_mutex_lock(&thd->LOCK_thd_data);

  if (thd->query())
  {
    if (max_query_len < 1)
      len= thd->query_length();
    else
      len= min(thd->query_length(), max_query_len);
    str.append('\n');
    str.append(thd->query(), len);
  }

  mysql_mutex_unlock(&thd->LOCK_thd_data);

  if (str.c_ptr_safe() == buffer)
    return buffer;

  /*
    We have to copy the new string to the destination buffer because the string
    was reallocated to a larger buffer to be able to fit.
  */
  DBUG_ASSERT(buffer != NULL);
  length= min(str.length(), length-1);
  memcpy(buffer, str.c_ptr_quick(), length);
  /* Make sure that the new string is null terminated */
  buffer[length]= '\0';
  return buffer;
}


bool Drop_table_error_handler::handle_condition(THD *thd,
                                                uint sql_errno,
                                                const char* sqlstate,
                                                Sql_condition::enum_warning_level level,
                                                const char* msg,
                                                Sql_condition ** cond_hdl)
{
  *cond_hdl= NULL;
  return ((sql_errno == EE_DELETE && my_errno == ENOENT) ||
          sql_errno == ER_TRG_NO_DEFINER);
}


void Open_tables_state::set_open_tables_state(Open_tables_state *state)
{
  this->open_tables= state->open_tables;

  this->temporary_tables= state->temporary_tables;
  this->derived_tables= state->derived_tables;

  this->lock= state->lock;
  this->extra_lock= state->extra_lock;

  this->locked_tables_mode= state->locked_tables_mode;
  this->current_tablenr= state->current_tablenr;

  this->state_flags= state->state_flags;

  this->reset_reprepare_observers();
  for (int i= 0; i < state->m_reprepare_observers.elements(); ++i)
    this->push_reprepare_observer(state->m_reprepare_observers.at(i));
}


void Open_tables_state::reset_open_tables_state()
{
  open_tables= NULL;
  temporary_tables= NULL;
  derived_tables= NULL;
  lock= NULL;
  extra_lock= NULL;
  locked_tables_mode= LTM_NONE;
  // JOH: What about resetting current_tablenr?
  state_flags= 0U;
  reset_reprepare_observers();
}


THD::THD(bool enable_plugins)
   :Statement(&main_lex, &main_mem_root, STMT_CONVENTIONAL_EXECUTION,
              /* statement id */ 0),
   rli_fake(0), rli_slave(NULL),
   in_sub_stmt(0),
   fill_status_recursion_level(0),
   binlog_row_event_extra_data(NULL),
   binlog_unsafe_warning_flags(0),
   binlog_table_maps(0),
   binlog_accessed_db_names(NULL),
   m_trans_log_file(NULL),
   m_trans_fixed_log_file(NULL),
   m_trans_end_pos(0),
   table_map_for_update(0),
   arg_of_last_insert_id_function(FALSE),
   first_successful_insert_id_in_prev_stmt(0),
   first_successful_insert_id_in_prev_stmt_for_binlog(0),
   first_successful_insert_id_in_cur_stmt(0),
   stmt_depends_on_first_successful_insert_id_in_prev_stmt(FALSE),
   m_examined_row_count(0),
   m_statement_psi(NULL),
   m_idle_psi(NULL),
   m_server_idle(false),
   next_to_commit(NULL),
   is_fatal_error(0),
   transaction_rollback_request(0),
   is_fatal_sub_stmt_error(0),
   rand_used(0),
   time_zone_used(0),
   in_lock_tables(0),
   bootstrap(0),
   derived_tables_processing(FALSE),
   sp_runtime_ctx(NULL),
   m_parser_state(NULL),
#if defined(ENABLED_DEBUG_SYNC)
   debug_sync_control(0),
#endif /* defined(ENABLED_DEBUG_SYNC) */
   m_enable_plugins(enable_plugins),
   owned_gtid_set(global_sid_map),
   main_da(0, false),
   m_stmt_da(&main_da)
{
  ulong tmp;

  mdl_context.init(this);
  /*
    Pass nominal parameters to init_alloc_root only to ensure that
    the destructor works OK in case of an error. The main_mem_root
    will be re-initialized in init_for_queries().
  */
  init_sql_alloc(&main_mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
  stmt_arena= this;
  thread_stack= 0;
  catalog= (char*)"std"; // the only catalog we have for now
  main_security_ctx.init();
  security_ctx= &main_security_ctx;
  no_errors= 0;
  password= 0;
  query_start_used= query_start_usec_used= 0;
  count_cuted_fields= CHECK_FIELD_IGNORE;
  killed= NOT_KILLED;
  col_access=0;
  is_slave_error= thread_specific_used= FALSE;
  my_hash_clear(&handler_tables_hash);
  tmp_table=0;
  cuted_fields= 0L;
  m_sent_row_count= 0L;
  limit_found_rows= 0;
  m_row_count_func= -1;
  statement_id_counter= 0UL;
  // Must be reset to handle error with THD's created for init of mysqld
  lex->current_select= 0;
  user_time.tv_sec= 0;
  user_time.tv_usec= 0;
  start_time.tv_sec= 0;
  start_time.tv_usec= 0;
  start_utime= prior_thr_create_utime= 0L;
  utime_after_lock= 0L;
  current_linfo =  0;
  slave_thread = 0;
  memset(&variables, 0, sizeof(variables));
  thread_id= 0;
  one_shot_set= 0;
  file_id = 0;
  query_id= 0;
  query_name_consts= 0;
  db_charset= global_system_variables.collation_database;
  memset(ha_data, 0, sizeof(ha_data));
  mysys_var=0;
  binlog_evt_union.do_union= FALSE;
  enable_slow_log= 0;
  commit_error= CE_NONE;
  durability_property= HA_REGULAR_DURABILITY;
#ifndef DBUG_OFF
  dbug_sentry=THD_SENTRY_MAGIC;
#endif
#ifndef EMBEDDED_LIBRARY
  mysql_audit_init_thd(this);
  net.vio=0;
#endif
  client_capabilities= 0;                       // minimalistic client
  ull=0;
  system_thread= NON_SYSTEM_THREAD;
  cleanup_done= abort_on_warning= 0;
  m_release_resources_done= false;
  peer_port= 0;                                 // For SHOW PROCESSLIST
  transaction.m_pending_rows_event= 0;
  transaction.flags.enabled= true;
#ifdef SIGNAL_WITH_VIO_SHUTDOWN
  active_vio = 0;
#endif
  mysql_mutex_init(key_LOCK_thd_data, &LOCK_thd_data, MY_MUTEX_INIT_FAST);

  /* Variables with default values */
  proc_info="login";
  where= THD::DEFAULT_WHERE;
  server_id = ::server_id;
  unmasked_server_id = server_id;
  slave_net = 0;
  set_command(COM_CONNECT);
  *scramble= '\0';

  /* Call to init() below requires fully initialized Open_tables_state. */
  reset_open_tables_state();

  init();
#if defined(ENABLED_PROFILING)
  profiling.set_thd(this);
#endif
  m_user_connect= NULL;
  my_hash_init(&user_vars, system_charset_info, USER_VARS_HASH_SIZE, 0, 0,
               (my_hash_get_key) get_var_key,
               (my_hash_free_key) free_user_var, 0);

  sp_proc_cache= NULL;
  sp_func_cache= NULL;

  /* For user vars replication*/
  if (opt_bin_log)
    my_init_dynamic_array(&user_var_events,
                          sizeof(BINLOG_USER_VAR_EVENT *), 16, 16);
  else
    memset(&user_var_events, 0, sizeof(user_var_events));

  /* Protocol */
  protocol= &protocol_text;                     // Default protocol
  protocol_text.init(this);
  protocol_binary.init(this);

  tablespace_op=FALSE;
  tmp= sql_rnd_with_mutex();
  randominit(&rand, tmp + (ulong) &rand, tmp + (ulong) ::global_query_id);
  substitute_null_with_insert_id = FALSE;
  thr_lock_info_init(&lock_info); /* safety: will be reset after start */

  m_internal_handler= NULL;
  m_binlog_invoker= FALSE;
  memset(&invoker_user, 0, sizeof(invoker_user));
  memset(&invoker_host, 0, sizeof(invoker_host));

  binlog_next_event_pos.file_name= NULL;
  binlog_next_event_pos.pos= 0;
#ifndef DBUG_OFF
  gis_debug= 0;
#endif
}


void THD::push_internal_handler(Internal_error_handler *handler)
{
  if (m_internal_handler)
  {
    handler->m_prev_internal_handler= m_internal_handler;
    m_internal_handler= handler;
  }
  else
  {
    m_internal_handler= handler;
  }
}

bool THD::handle_condition(uint sql_errno,
                           const char* sqlstate,
                           Sql_condition::enum_warning_level level,
                           const char* msg,
                           Sql_condition ** cond_hdl)
{
  if (!m_internal_handler)
  {
    *cond_hdl= NULL;
    return FALSE;
  }

  for (Internal_error_handler *error_handler= m_internal_handler;
       error_handler;
       error_handler= error_handler->m_prev_internal_handler)
  {
    if (error_handler->handle_condition(this, sql_errno, sqlstate, level, msg,
                                        cond_hdl))
    {
      return TRUE;
    }
  }

  return FALSE;
}


Internal_error_handler *THD::pop_internal_handler()
{
  DBUG_ASSERT(m_internal_handler != NULL);
  Internal_error_handler *popped_handler= m_internal_handler;
  m_internal_handler= m_internal_handler->m_prev_internal_handler;
  return popped_handler;
}


void THD::raise_error(uint sql_errno)
{
  const char* msg= ER(sql_errno);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_ERROR,
                         msg);
}

void THD::raise_error_printf(uint sql_errno, ...)
{
  va_list args;
  char ebuff[MYSQL_ERRMSG_SIZE];
  DBUG_ENTER("THD::raise_error_printf");
  DBUG_PRINT("my", ("nr: %d  errno: %d", sql_errno, errno));
  const char* format= ER(sql_errno);
  va_start(args, sql_errno);
  my_vsnprintf(ebuff, sizeof(ebuff), format, args);
  va_end(args);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_ERROR,
                         ebuff);
  DBUG_VOID_RETURN;
}

void THD::raise_warning(uint sql_errno)
{
  const char* msg= ER(sql_errno);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_WARN,
                         msg);
}

void THD::raise_warning_printf(uint sql_errno, ...)
{
  va_list args;
  char    ebuff[MYSQL_ERRMSG_SIZE];
  DBUG_ENTER("THD::raise_warning_printf");
  DBUG_PRINT("enter", ("warning: %u", sql_errno));
  const char* format= ER(sql_errno);
  va_start(args, sql_errno);
  my_vsnprintf(ebuff, sizeof(ebuff), format, args);
  va_end(args);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_WARN,
                         ebuff);
  DBUG_VOID_RETURN;
}

void THD::raise_note(uint sql_errno)
{
  DBUG_ENTER("THD::raise_note");
  DBUG_PRINT("enter", ("code: %d", sql_errno));
  if (!(variables.option_bits & OPTION_SQL_NOTES))
    DBUG_VOID_RETURN;
  const char* msg= ER(sql_errno);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_NOTE,
                         msg);
  DBUG_VOID_RETURN;
}

void THD::raise_note_printf(uint sql_errno, ...)
{
  va_list args;
  char    ebuff[MYSQL_ERRMSG_SIZE];
  DBUG_ENTER("THD::raise_note_printf");
  DBUG_PRINT("enter",("code: %u", sql_errno));
  if (!(variables.option_bits & OPTION_SQL_NOTES))
    DBUG_VOID_RETURN;
  const char* format= ER(sql_errno);
  va_start(args, sql_errno);
  my_vsnprintf(ebuff, sizeof(ebuff), format, args);
  va_end(args);
  (void) raise_condition(sql_errno,
                         NULL,
                         Sql_condition::WARN_LEVEL_NOTE,
                         ebuff);
  DBUG_VOID_RETURN;
}


struct timeval THD::query_start_timeval_trunc(uint decimals)
{
  struct timeval tv;
  tv.tv_sec= start_time.tv_sec;
  query_start_used= 1;
  if (decimals)
  {
    tv.tv_usec= start_time.tv_usec;
    my_timeval_trunc(&tv, decimals);
    query_start_usec_used= 1;
  }
  else
  {
    tv.tv_usec= 0;
  }
  return tv;
}


Sql_condition* THD::raise_condition(uint sql_errno,
                                    const char* sqlstate,
                                    Sql_condition::enum_warning_level level,
                                    const char* msg)
{
  Diagnostics_area *da= get_stmt_da();
  Sql_condition *cond= NULL;
  DBUG_ENTER("THD::raise_condition");

  if (!(variables.option_bits & OPTION_SQL_NOTES) &&
      (level == Sql_condition::WARN_LEVEL_NOTE))
    DBUG_RETURN(NULL);

  da->opt_clear_warning_info(query_id);

  /*
    TODO: replace by DBUG_ASSERT(sql_errno != 0) once all bugs similar to
    Bug#36768 are fixed: a SQL condition must have a real (!=0) error number
    so that it can be caught by handlers.
  */
  if (sql_errno == 0)
    sql_errno= ER_UNKNOWN_ERROR;
  if (msg == NULL)
    msg= ER(sql_errno);
  if (sqlstate == NULL)
   sqlstate= mysql_errno_to_sqlstate(sql_errno);

  if ((level == Sql_condition::WARN_LEVEL_WARN) &&
      really_abort_on_warning())
  {
    /*
      FIXME:
      push_warning and strict SQL_MODE case.
    */
    level= Sql_condition::WARN_LEVEL_ERROR;
    killed= THD::KILL_BAD_DATA;
  }

  switch (level)
  {
  case Sql_condition::WARN_LEVEL_NOTE:
  case Sql_condition::WARN_LEVEL_WARN:
    got_warning= 1;
    break;
  case Sql_condition::WARN_LEVEL_ERROR:
    break;
  default:
    DBUG_ASSERT(FALSE);
  }

  if (handle_condition(sql_errno, sqlstate, level, msg, &cond))
    DBUG_RETURN(cond);

  if (level == Sql_condition::WARN_LEVEL_ERROR)
  {
    is_slave_error=  1; // needed to catch query errors during replication

    /*
      thd->lex->current_select == 0 if lex structure is not inited
      (not query command (COM_QUERY))
    */
    if (lex->current_select &&
        lex->current_select->no_error && !is_fatal_error)
    {
      DBUG_PRINT("error",
                 ("Error converted to warning: current_select: no_error %d  "
                  "fatal_error: %d",
                  (lex->current_select ?
                   lex->current_select->no_error : 0),
                  (int) is_fatal_error));
    }
    else
    {
      if (!da->is_error())
      {
        set_row_count_func(-1);
        da->set_error_status(sql_errno, msg, sqlstate, cond);
      }
    }
  }

  query_cache_abort(&query_cache_tls);

  /* 
     Avoid pushing a condition for fatal out of memory errors as this will 
     require memory allocation and therefore might fail. Non fatal out of 
     memory errors can occur if raised by SIGNAL/RESIGNAL statement.
  */
  if (!(is_fatal_error && (sql_errno == EE_OUTOFMEMORY ||
                           sql_errno == ER_OUTOFMEMORY)))
  {
    cond= da->push_warning(this, sql_errno, sqlstate, level, msg);
  }
  DBUG_RETURN(cond);
}

extern "C"
void *thd_alloc(MYSQL_THD thd, unsigned int size)
{
  return thd->alloc(size);
}

extern "C"
void *thd_calloc(MYSQL_THD thd, unsigned int size)
{
  return thd->calloc(size);
}

extern "C"
char *thd_strdup(MYSQL_THD thd, const char *str)
{
  return thd->strdup(str);
}

extern "C"
char *thd_strmake(MYSQL_THD thd, const char *str, unsigned int size)
{
  return thd->strmake(str, size);
}

extern "C"
LEX_STRING *thd_make_lex_string(THD *thd, LEX_STRING *lex_str,
                                const char *str, unsigned int size,
                                int allocate_lex_string)
{
  return thd->make_lex_string(lex_str, str, size,
                              (bool) allocate_lex_string);
}

extern "C"
void *thd_memdup(MYSQL_THD thd, const void* str, unsigned int size)
{
  return thd->memdup(str, size);
}

extern "C"
void thd_get_xid(const MYSQL_THD thd, MYSQL_XID *xid)
{
  *xid = *(MYSQL_XID *) &thd->transaction.xid_state.xid;
}

#ifdef _WIN32
extern "C"   THD *_current_thd_noinline(void)
{
  return my_pthread_getspecific_ptr(THD*,THR_THD);
}
#endif
/*
  Init common variables that has to be reset on start and on change_user
*/

void THD::init(void)
{
  mysql_mutex_lock(&LOCK_global_system_variables);
  plugin_thdvar_init(this, m_enable_plugins);
  /*
    variables= global_system_variables above has reset
    variables.pseudo_thread_id to 0. We need to correct it here to
    avoid temporary tables replication failure.
  */
  variables.pseudo_thread_id= thread_id;
  mysql_mutex_unlock(&LOCK_global_system_variables);
  server_status= SERVER_STATUS_AUTOCOMMIT;
  if (variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES)
    server_status|= SERVER_STATUS_NO_BACKSLASH_ESCAPES;

  transaction.all.reset_unsafe_rollback_flags();
  transaction.stmt.reset_unsafe_rollback_flags();
  open_options=ha_open_options;
  update_lock_default= (variables.low_priority_updates ?
                        TL_WRITE_LOW_PRIORITY :
                        TL_WRITE);
  tx_isolation= (enum_tx_isolation) variables.tx_isolation;
  tx_read_only= variables.tx_read_only;
  update_charset();
  reset_current_stmt_binlog_format_row();
  reset_binlog_local_stmt_filter();
  memset(&status_var, 0, sizeof(status_var));
  binlog_row_event_extra_data= 0;

  if (variables.sql_log_bin)
    variables.option_bits|= OPTION_BIN_LOG;
  else
    variables.option_bits&= ~OPTION_BIN_LOG;

#if defined(ENABLED_DEBUG_SYNC)
  /* Initialize the Debug Sync Facility. See debug_sync.cc. */
  debug_sync_init_thread(this);
#endif /* defined(ENABLED_DEBUG_SYNC) */

  owned_gtid.sidno= 0;
  owned_gtid.gno= 0;
}


/*
  Init THD for query processing.
  This has to be called once before we call mysql_parse.
  See also comments in sql_class.h.
*/

void THD::init_for_queries(Relay_log_info *rli)
{
  set_time(); 
  ha_enable_transaction(this,TRUE);

  reset_root_defaults(mem_root, variables.query_alloc_block_size,
                      variables.query_prealloc_size);
  reset_root_defaults(&transaction.mem_root,
                      variables.trans_alloc_block_size,
                      variables.trans_prealloc_size);
  transaction.xid_state.xid.null();
  transaction.xid_state.in_thd=1;
#if defined(MYSQL_SERVER) && defined(HAVE_REPLICATION)
  if (rli)
  {
    if ((rli->deferred_events_collecting= rpl_filter->is_on()))
    {
      rli->deferred_events= new Deferred_log_events(rli);
    }
    rli_slave= rli;

    DBUG_ASSERT(rli_slave->info_thd == this && slave_thread);
  }
#endif
}


/*
  Do what's needed when one invokes change user

  SYNOPSIS
    change_user()

  IMPLEMENTATION
    Reset all resources that are connection specific
*/


void THD::change_user(void)
{
  mysql_mutex_lock(&LOCK_status);
  add_to_status(&global_status_var, &status_var);
  mysql_mutex_unlock(&LOCK_status);

  cleanup();
  killed= NOT_KILLED;
  cleanup_done= 0;
  init();
  stmt_map.reset();
  my_hash_init(&user_vars, system_charset_info, USER_VARS_HASH_SIZE, 0, 0,
               (my_hash_get_key) get_var_key,
               (my_hash_free_key) free_user_var, 0);
  sp_cache_clear(&sp_proc_cache);
  sp_cache_clear(&sp_func_cache);
}


/*
  Do what's needed when one invokes change user.
  Also used during THD::release_resources, i.e. prior to THD destruction.
*/
void THD::cleanup(void)
{
  DBUG_ENTER("THD::cleanup");
  DBUG_ASSERT(cleanup_done == 0);

  killed= KILL_CONNECTION;
#ifdef ENABLE_WHEN_BINLOG_WILL_BE_ABLE_TO_PREPARE
  if (transaction.xid_state.xa_state == XA_PREPARED)
  {
#error xid_state in the cache should be replaced by the allocated value
  }
#endif
  {
    transaction.xid_state.xa_state= XA_NOTR;
    trans_rollback(this);
    xid_cache_delete(&transaction.xid_state);
  }

  locked_tables_list.unlock_locked_tables(this);
  mysql_ha_cleanup(this);

  DBUG_ASSERT(open_tables == NULL);
  /*
    If the thread was in the middle of an ongoing transaction (rolled
    back a few lines above) or under LOCK TABLES (unlocked the tables
    and left the mode a few lines above), there will be outstanding
    metadata locks. Release them.
  */
  mdl_context.release_transactional_locks();

  /* Release the global read lock, if acquired. */
  if (global_read_lock.is_acquired())
    global_read_lock.unlock_global_read_lock(this);

  /* All metadata locks must have been released by now. */
  DBUG_ASSERT(!mdl_context.has_locks());

#if defined(ENABLED_DEBUG_SYNC)
  /* End the Debug Sync Facility. See debug_sync.cc. */
  debug_sync_end_thread(this);
#endif /* defined(ENABLED_DEBUG_SYNC) */

  delete_dynamic(&user_var_events);
  my_hash_free(&user_vars);
  if (gtid_mode > 0)
    variables.gtid_next.set_automatic();
  close_temporary_tables(this);
  sp_cache_clear(&sp_proc_cache);
  sp_cache_clear(&sp_func_cache);

  if (ull)
  {
    mysql_mutex_lock(&LOCK_user_locks);
    item_user_lock_release(ull);
    mysql_mutex_unlock(&LOCK_user_locks);
    ull= NULL;
  }

  /*
    Actions above might generate events for the binary log, so we
    commit the current transaction coordinator after executing cleanup
    actions.
   */
  if (tc_log)
    tc_log->commit(this, true);

  cleanup_done=1;
  DBUG_VOID_RETURN;
}


void THD::release_resources()
{
  mysql_mutex_assert_not_owner(&LOCK_thread_count);
  DBUG_ASSERT(m_release_resources_done == false);

  mysql_mutex_lock(&LOCK_status);
  add_to_status(&global_status_var, &status_var);
  mysql_mutex_unlock(&LOCK_status);

  /* Ensure that no one is using THD */
  mysql_mutex_lock(&LOCK_thd_data);

  /* Close connection */
#ifndef EMBEDDED_LIBRARY
  if (net.vio)
  {
    vio_delete(net.vio);
    net_end(&net);
    net.vio= NULL;
  }
#endif
  mysql_mutex_unlock(&LOCK_thd_data);

  stmt_map.reset();                     /* close all prepared statements */
  if (!cleanup_done)
    cleanup();

  mdl_context.destroy();
  ha_close_connection(this);
  mysql_audit_release(this);
  if (m_enable_plugins)
    plugin_thdvar_cleanup(this);

  m_release_resources_done= true;
}


THD::~THD()
{
  mysql_mutex_assert_not_owner(&LOCK_thread_count);
  THD_CHECK_SENTRY(this);
  DBUG_ENTER("~THD()");
  DBUG_PRINT("info", ("THD dtor, this %p", this));

  if (!m_release_resources_done)
    release_resources();

  clear_next_event_pos();

  /* Ensure that no one is using THD */
  mysql_mutex_lock(&LOCK_thd_data);
  mysql_mutex_unlock(&LOCK_thd_data);

  DBUG_PRINT("info", ("freeing security context"));
  main_security_ctx.destroy();
  my_free(db);
  db= NULL;
  free_root(&transaction.mem_root,MYF(0));
  mysql_mutex_destroy(&LOCK_thd_data);
#ifndef DBUG_OFF
  dbug_sentry= THD_SENTRY_GONE;
#endif  
#ifndef EMBEDDED_LIBRARY
  if (rli_fake)
  {
    rli_fake->end_info();
    delete rli_fake;
    rli_fake= NULL;
  }

  if (variables.gtid_next_list.gtid_set != NULL)
  {
#ifdef HAVE_GTID_NEXT_LIST
    delete variables.gtid_next_list.gtid_set;
    variables.gtid_next_list.gtid_set= NULL;
    variables.gtid_next_list.is_non_null= false;
#else
    DBUG_ASSERT(0);
#endif
  }
  
  mysql_audit_free_thd(this);
  if (rli_slave)
    rli_slave->cleanup_after_session();
#endif

  free_root(&main_mem_root, MYF(0));
  DBUG_VOID_RETURN;
}


/*
  Add all status variables to another status variable array

  SYNOPSIS
   add_to_status()
   to_var       add to this array
   from_var     from this array

  NOTES
    This function assumes that all variables are longlong/ulonglong.
    If this assumption will change, then we have to explictely add
    the other variables after the while loop
*/

void add_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var)
{
  int        c;
  ulonglong *end= (ulonglong*) ((uchar*) to_var +
                                offsetof(STATUS_VAR, last_system_status_var) +
                                sizeof(ulonglong));
  ulonglong *to= (ulonglong*) to_var, *from= (ulonglong*) from_var;

  while (to != end)
    *(to++)+= *(from++);

  to_var->com_other+= from_var->com_other;

  for (c= 0; c< SQLCOM_END; c++)
    to_var->com_stat[(uint) c] += from_var->com_stat[(uint) c];
}

/*
  Add the difference between two status variable arrays to another one.

  SYNOPSIS
    add_diff_to_status
    to_var       add to this array
    from_var     from this array
    dec_var      minus this array
  
  NOTE
    This function assumes that all variables are longlong/ulonglong.
*/

void add_diff_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var,
                        STATUS_VAR *dec_var)
{
  int        c;
  ulonglong *end= (ulonglong*) ((uchar*) to_var + offsetof(STATUS_VAR,
                                                           last_system_status_var) +
                                sizeof(ulonglong));
  ulonglong *to= (ulonglong*) to_var,
            *from= (ulonglong*) from_var,
            *dec= (ulonglong*) dec_var;

  while (to != end)
    *(to++)+= *(from++) - *(dec++);

  to_var->com_other+= from_var->com_other - dec_var->com_other;

  for (c= 0; c< SQLCOM_END; c++)
    to_var->com_stat[(uint) c] += from_var->com_stat[(uint) c] -dec_var->com_stat[(uint) c];
}


void THD::awake(THD::killed_state state_to_set)
{
  DBUG_ENTER("THD::awake");
  DBUG_PRINT("enter", ("this: %p current_thd: %p", this, current_thd));
  THD_CHECK_SENTRY(this);
  mysql_mutex_assert_owner(&LOCK_thd_data);

  /* Set the 'killed' flag of 'this', which is the target THD object. */
  killed= state_to_set;

  if (state_to_set != THD::KILL_QUERY)
  {
#ifdef SIGNAL_WITH_VIO_SHUTDOWN
    if (this != current_thd)
    {
      /*
        Before sending a signal, let's close the socket of the thread
        that is being killed ("this", which is not the current thread).
        This is to make sure it does not block if the signal is lost.
        This needs to be done only on platforms where signals are not
        a reliable interruption mechanism.

        Note that the downside of this mechanism is that we could close
        the connection while "this" target thread is in the middle of
        sending a result to the application, thus violating the client-
        server protocol.

        On the other hand, without closing the socket we have a race
        condition. If "this" target thread passes the check of
        thd->killed, and then the current thread runs through
        THD::awake(), sets the 'killed' flag and completes the
        signaling, and then the target thread runs into read(), it will
        block on the socket. As a result of the discussions around
        Bug#37780, it has been decided that we accept the race
        condition. A second KILL awakes the target from read().

        If we are killing ourselves, we know that we are not blocked.
        We also know that we will check thd->killed before we go for
        reading the next statement.
      */

      shutdown_active_vio();
    }
#endif

    /* Mark the target thread's alarm request expired, and signal alarm. */
    thr_alarm_kill(thread_id);

    /* Send an event to the scheduler that a thread should be killed. */
    if (!slave_thread)
      MYSQL_CALLBACK(thread_scheduler, post_kill_notification, (this));
  }

  /* Broadcast a condition to kick the target if it is waiting on it. */
  if (mysys_var)
  {
    mysql_mutex_lock(&mysys_var->mutex);
    if (!system_thread)         // Don't abort locks
      mysys_var->abort=1;
    /*
      This broadcast could be up in the air if the victim thread
      exits the cond in the time between read and broadcast, but that is
      ok since all we want to do is to make the victim thread get out
      of waiting on current_cond.
      If we see a non-zero current_cond: it cannot be an old value (because
      then exit_cond() should have run and it can't because we have mutex); so
      it is the true value but maybe current_mutex is not yet non-zero (we're
      in the middle of enter_cond() and there is a "memory order
      inversion"). So we test the mutex too to not lock 0.

      Note that there is a small chance we fail to kill. If victim has locked
      current_mutex, but hasn't yet entered enter_cond() (which means that
      current_cond and current_mutex are 0), then the victim will not get
      a signal and it may wait "forever" on the cond (until
      we issue a second KILL or the status it's waiting for happens).
      It's true that we have set its thd->killed but it may not
      see it immediately and so may have time to reach the cond_wait().

      However, where possible, we test for killed once again after
      enter_cond(). This should make the signaling as safe as possible.
      However, there is still a small chance of failure on platforms with
      instruction or memory write reordering.
    */
    if (mysys_var->current_cond && mysys_var->current_mutex)
    {
      mysql_mutex_lock(mysys_var->current_mutex);
      mysql_cond_broadcast(mysys_var->current_cond);
      mysql_mutex_unlock(mysys_var->current_mutex);
    }
    mysql_mutex_unlock(&mysys_var->mutex);
  }
  DBUG_VOID_RETURN;
}


void THD::disconnect()
{
  Vio *vio= NULL;

  mysql_mutex_lock(&LOCK_thd_data);

  killed= THD::KILL_CONNECTION;

#ifdef SIGNAL_WITH_VIO_SHUTDOWN
  /*
    Since a active vio might might have not been set yet, in
    any case save a reference to avoid closing a inexistent
    one or closing the vio twice if there is a active one.
  */
  vio= active_vio;
  shutdown_active_vio();
#endif

  /* Disconnect even if a active vio is not associated. */
  if (net.vio != vio && net.vio != NULL)
  {
    vio_shutdown(net.vio);
  }

  mysql_mutex_unlock(&LOCK_thd_data);
}


bool THD::notify_shared_lock(MDL_context_owner *ctx_in_use,
                             bool needs_thr_lock_abort)
{
  THD *in_use= ctx_in_use->get_thd();
  bool signalled= FALSE;
  if ((in_use->system_thread & SYSTEM_THREAD_DELAYED_INSERT) &&
      !in_use->killed)
  {
    in_use->killed= THD::KILL_CONNECTION;
    mysql_mutex_lock(&in_use->mysys_var->mutex);
    if (in_use->mysys_var->current_cond)
      mysql_cond_broadcast(in_use->mysys_var->current_cond);
    mysql_mutex_unlock(&in_use->mysys_var->mutex);
    signalled= TRUE;
  }

  if (needs_thr_lock_abort)
  {
    mysql_mutex_lock(&in_use->LOCK_thd_data);
    for (TABLE *thd_table= in_use->open_tables;
         thd_table ;
         thd_table= thd_table->next)
    {
      /*
        Check for TABLE::needs_reopen() is needed since in some places we call
        handler::close() for table instance (and set TABLE::db_stat to 0)
        and do not remove such instances from the THD::open_tables
        for some time, during which other thread can see those instances
        (e.g. see partitioning code).
      */
      if (!thd_table->needs_reopen())
        signalled|= mysql_lock_abort_for_thread(this, thd_table);
    }
    mysql_mutex_unlock(&in_use->LOCK_thd_data);
  }
  return signalled;
}


/*
  Remember the location of thread info, the structure needed for
  sql_alloc() and the structure for the net buffer
*/

bool THD::store_globals()
{
  /*
    Assert that thread_stack is initialized: it's necessary to be able
    to track stack overrun.
  */
  DBUG_ASSERT(thread_stack);

  if (my_pthread_setspecific_ptr(THR_THD,  this) ||
      my_pthread_setspecific_ptr(THR_MALLOC, &mem_root))
    return 1;
  /*
    mysys_var is concurrently readable by a killer thread.
    It is protected by LOCK_thd_data, it is not needed to lock while the
    pointer is changing from NULL not non-NULL. If the kill thread reads
    NULL it doesn't refer to anything, but if it is non-NULL we need to
    ensure that the thread doesn't proceed to assign another thread to
    have the mysys_var reference (which in fact refers to the worker
    threads local storage with key THR_KEY_mysys. 
  */
  mysys_var=my_thread_var;
  DBUG_PRINT("debug", ("mysys_var: 0x%llx", (ulonglong) mysys_var));
  /*
    Let mysqld define the thread id (not mysys)
    This allows us to move THD to different threads if needed.
  */
  mysys_var->id= thread_id;
  real_id= pthread_self();                      // For debugging

  /*
    We have to call thr_lock_info_init() again here as THD may have been
    created in another thread
  */
  thr_lock_info_init(&lock_info);
  return 0;
}

/*
  Remove the thread specific info (THD and mem_root pointer) stored during
  store_global call for this thread.
*/
bool THD::restore_globals()
{
  /*
    Assert that thread_stack is initialized: it's necessary to be able
    to track stack overrun.
  */
  DBUG_ASSERT(thread_stack);
  
  /* Undocking the thread specific data. */
  my_pthread_setspecific_ptr(THR_THD, NULL);
  my_pthread_setspecific_ptr(THR_MALLOC, NULL);
  
  return 0;
}


/*
  Cleanup after query.

  SYNOPSIS
    THD::cleanup_after_query()

  DESCRIPTION
    This function is used to reset thread data to its default state.

  NOTE
    This function is not suitable for setting thread data to some
    non-default values, as there is only one replication thread, so
    different master threads may overwrite data of each other on
    slave.
*/

void THD::cleanup_after_query()
{
  /*
    Reset rand_used so that detection of calls to rand() will save random 
    seeds if needed by the slave.

    Do not reset rand_used if inside a stored function or trigger because 
    only the call to these operations is logged. Thus only the calling 
    statement needs to detect rand() calls made by its substatements. These
    substatements must not set rand_used to 0 because it would remove the
    detection of rand() by the calling statement. 
  */
  if (!in_sub_stmt) /* stored functions and triggers are a special case */
  {
    /* Forget those values, for next binlogger: */
    stmt_depends_on_first_successful_insert_id_in_prev_stmt= 0;
    auto_inc_intervals_in_cur_stmt_for_binlog.empty();
    rand_used= 0;
    binlog_accessed_db_names= NULL;
    m_trans_fixed_log_file= NULL;

    if (gtid_mode > 0)
      gtid_post_statement_checks(this);
#ifndef EMBEDDED_LIBRARY
    /*
      Clean possible unused INSERT_ID events by current statement.
      is_update_query() is needed to ignore SET statements:
        Statements that don't update anything directly and don't
        used stored functions. This is mostly necessary to ignore
        statements in binlog between SET INSERT_ID and DML statement
        which is intended to consume its event (there can be other
        SET statements between them).
    */
    if ((rli_slave || rli_fake) && is_update_query(lex->sql_command))
      auto_inc_intervals_forced.empty();
#endif
  }
  /*
    Forget the binlog stmt filter for the next query.
    There are some code paths that:
    - do not call THD::decide_logging_format()
    - do call THD::binlog_query(),
    making this reset necessary.
  */
  reset_binlog_local_stmt_filter();
  if (first_successful_insert_id_in_cur_stmt > 0)
  {
    /* set what LAST_INSERT_ID() will return */
    first_successful_insert_id_in_prev_stmt= 
      first_successful_insert_id_in_cur_stmt;
    first_successful_insert_id_in_cur_stmt= 0;
    substitute_null_with_insert_id= TRUE;
  }
  arg_of_last_insert_id_function= 0;
  /* Free Items that were created during this execution */
  free_items();
  /* Reset where. */
  where= THD::DEFAULT_WHERE;
  /* reset table map for multi-table update */
  table_map_for_update= 0;
  m_binlog_invoker= FALSE;
  /* reset replication info structure */
  if (lex && lex->mi.repl_ignore_server_ids.buffer) 
  {
    delete_dynamic(&lex->mi.repl_ignore_server_ids);
  }
#ifndef EMBEDDED_LIBRARY
  if (rli_slave)
    rli_slave->cleanup_after_query();
#endif
}


LEX_STRING *
make_lex_string_root(MEM_ROOT *mem_root,
                     LEX_STRING *lex_str, const char* str, uint length,
                     bool allocate_lex_string)
{
  if (allocate_lex_string)
    if (!(lex_str= (LEX_STRING *)alloc_root(mem_root, sizeof(LEX_STRING))))
      return 0;
  if (!(lex_str->str= strmake_root(mem_root, str, length)))
    return 0;
  lex_str->length= length;
  return lex_str;
}

LEX_STRING *THD::make_lex_string(LEX_STRING *lex_str,
                                 const char* str, uint length,
                                 bool allocate_lex_string)
{
  return make_lex_string_root (mem_root, lex_str, str,
                               length, allocate_lex_string);
}


/*
  Convert a string to another character set

  SYNOPSIS
    convert_string()
    to                          Store new allocated string here
    to_cs                       New character set for allocated string
    from                        String to convert
    from_length                 Length of string to convert
    from_cs                     Original character set

  NOTES
    to will be 0-terminated to make it easy to pass to system funcs

  RETURN
    0   ok
    1   End of memory.
        In this case to->str will point to 0 and to->length will be 0.
*/

bool THD::convert_string(LEX_STRING *to, const CHARSET_INFO *to_cs,
                         const char *from, uint from_length,
                         const CHARSET_INFO *from_cs)
{
  DBUG_ENTER("convert_string");
  size_t new_length= to_cs->mbmaxlen * from_length;
  uint dummy_errors;
  if (!(to->str= (char*) alloc(new_length+1)))
  {
    to->length= 0;                              // Safety fix
    DBUG_RETURN(1);                             // EOM
  }
  to->length= copy_and_convert((char*) to->str, new_length, to_cs,
                               from, from_length, from_cs, &dummy_errors);
  to->str[to->length]=0;                        // Safety
  DBUG_RETURN(0);
}


/*
  Convert string from source character set to target character set inplace.

  SYNOPSIS
    THD::convert_string

  DESCRIPTION
    Convert string using convert_buffer - buffer for character set 
    conversion shared between all protocols.

  RETURN
    0   ok
   !0   out of memory
*/

bool THD::convert_string(String *s, const CHARSET_INFO *from_cs,
                         const CHARSET_INFO *to_cs)
{
  uint dummy_errors;
  if (convert_buffer.copy(s->ptr(), s->length(), from_cs, to_cs, &dummy_errors))
    return TRUE;
  /* If convert_buffer >> s copying is more efficient long term */
  if (convert_buffer.alloced_length() >= convert_buffer.length() * 2 ||
      !s->is_alloced())
  {
    return s->copy(convert_buffer);
  }
  s->swap(convert_buffer);
  return FALSE;
}


/*
  Update some cache variables when character set changes
*/

void THD::update_charset()
{
  uint32 not_used;
  charset_is_system_charset=
    !String::needs_conversion(0,
                              variables.character_set_client,
                              system_charset_info,
                              &not_used);
  charset_is_collation_connection= 
    !String::needs_conversion(0,
                              variables.character_set_client,
                              variables.collation_connection,
                              &not_used);
  charset_is_character_set_filesystem= 
    !String::needs_conversion(0,
                              variables.character_set_client,
                              variables.character_set_filesystem,
                              &not_used);
}


/* routings to adding tables to list of changed in transaction tables */

inline static void list_include(CHANGED_TABLE_LIST** prev,
                                CHANGED_TABLE_LIST* curr,
                                CHANGED_TABLE_LIST* new_table)
{
  if (new_table)
  {
    *prev = new_table;
    (*prev)->next = curr;
  }
}

/* add table to list of changed in transaction tables */

void THD::add_changed_table(TABLE *table)
{
  DBUG_ENTER("THD::add_changed_table(table)");

  DBUG_ASSERT(in_multi_stmt_transaction_mode() && table->file->has_transactions());
  add_changed_table(table->s->table_cache_key.str,
                    (long) table->s->table_cache_key.length);
  DBUG_VOID_RETURN;
}


void THD::add_changed_table(const char *key, long key_length)
{
  DBUG_ENTER("THD::add_changed_table(key)");
  CHANGED_TABLE_LIST **prev_changed = &transaction.changed_tables;
  CHANGED_TABLE_LIST *curr = transaction.changed_tables;

  for (; curr; prev_changed = &(curr->next), curr = curr->next)
  {
    int cmp =  (long)curr->key_length - (long)key_length;
    if (cmp < 0)
    {
      list_include(prev_changed, curr, changed_table_dup(key, key_length));
      DBUG_PRINT("info", 
                 ("key_length: %ld  %u", key_length,
                  (*prev_changed)->key_length));
      DBUG_VOID_RETURN;
    }
    else if (cmp == 0)
    {
      cmp = memcmp(curr->key, key, curr->key_length);
      if (cmp < 0)
      {
        list_include(prev_changed, curr, changed_table_dup(key, key_length));
        DBUG_PRINT("info", 
                   ("key_length:  %ld  %u", key_length,
                    (*prev_changed)->key_length));
        DBUG_VOID_RETURN;
      }
      else if (cmp == 0)
      {
        DBUG_PRINT("info", ("already in list"));
        DBUG_VOID_RETURN;
      }
    }
  }
  *prev_changed = changed_table_dup(key, key_length);
  DBUG_PRINT("info", ("key_length: %ld  %u", key_length,
                      (*prev_changed)->key_length));
  DBUG_VOID_RETURN;
}


CHANGED_TABLE_LIST* THD::changed_table_dup(const char *key, long key_length)
{
  CHANGED_TABLE_LIST* new_table = 
    (CHANGED_TABLE_LIST*) trans_alloc(ALIGN_SIZE(sizeof(CHANGED_TABLE_LIST))+
                                      key_length + 1);
  if (!new_table)
  {
    my_error(EE_OUTOFMEMORY, MYF(ME_BELL+ME_FATALERROR),
             ALIGN_SIZE(sizeof(TABLE_LIST)) + key_length + 1);
    killed= KILL_CONNECTION;
    return 0;
  }

  new_table->key= ((char*)new_table)+ ALIGN_SIZE(sizeof(CHANGED_TABLE_LIST));
  new_table->next = 0;
  new_table->key_length = key_length;
  ::memcpy(new_table->key, key, key_length);
  return new_table;
}


int THD::send_explain_fields(select_result *result)
{
  List<Item> field_list;
  Item *item;
  CHARSET_INFO *cs= system_charset_info;
  field_list.push_back(new Item_return_int("id",3, MYSQL_TYPE_LONGLONG));
  field_list.push_back(new Item_empty_string("select_type", 19, cs));
  field_list.push_back(item= new Item_empty_string("table", NAME_CHAR_LEN, cs));
  item->maybe_null= 1;
  if (lex->describe & DESCRIBE_PARTITIONS)
  {
    /* Maximum length of string that make_used_partitions_str() can produce */
    item= new Item_empty_string("partitions", MAX_PARTITIONS * (1 + FN_LEN),
                                cs);
    field_list.push_back(item);
    item->maybe_null= 1;
  }
  field_list.push_back(item= new Item_empty_string("type", 10, cs));
  item->maybe_null= 1;
  field_list.push_back(item=new Item_empty_string("possible_keys",
                                                  NAME_CHAR_LEN*MAX_KEY, cs));
  item->maybe_null=1;
  field_list.push_back(item=new Item_empty_string("key", NAME_CHAR_LEN, cs));
  item->maybe_null=1;
  field_list.push_back(item=new Item_empty_string("key_len",
                                                  NAME_CHAR_LEN*MAX_KEY));
  item->maybe_null=1;
  field_list.push_back(item=new Item_empty_string("ref",
                                                  NAME_CHAR_LEN*MAX_REF_PARTS,
                                                  cs));
  item->maybe_null=1;
  field_list.push_back(item= new Item_return_int("rows", 10,
                                                 MYSQL_TYPE_LONGLONG));
  item->maybe_null= 1;
  if (lex->describe & DESCRIBE_EXTENDED)
  {
    field_list.push_back(item= new Item_float(NAME_STRING("filtered"),
                                              0.1234, 2, 4));
    item->maybe_null=1;
  }
  field_list.push_back(new Item_empty_string("Extra", 255, cs));
  item->maybe_null= 1;
  return (result->send_result_set_metadata(field_list,
                                           Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF));
}

#ifdef SIGNAL_WITH_VIO_SHUTDOWN
void THD::shutdown_active_vio()
{
  DBUG_ENTER("shutdown_active_vio");
  mysql_mutex_assert_owner(&LOCK_thd_data);
#ifndef EMBEDDED_LIBRARY
  if (active_vio)
  {
    vio_shutdown(active_vio);
    active_vio = 0;
  }
#endif
  DBUG_VOID_RETURN;
}
#endif


/*
  Register an item tree tree transformation, performed by the query
  optimizer. We need a pointer to runtime_memroot because it may be !=
  thd->mem_root (due to possible set_n_backup_active_arena called for thd).
*/

void THD::nocheck_register_item_tree_change(Item **place, Item *old_value,
                                            MEM_ROOT *runtime_memroot)
{
  Item_change_record *change;
  /*
    Now we use one node per change, which adds some memory overhead,
    but still is rather fast as we use alloc_root for allocations.
    A list of item tree changes of an average query should be short.
  */
  void *change_mem= alloc_root(runtime_memroot, sizeof(*change));
  if (change_mem == 0)
  {
    /*
      OOM, thd->fatal_error() is called by the error handler of the
      memroot. Just return.
    */
    return;
  }
  change= new (change_mem) Item_change_record;
  change->place= place;
  change->old_value= old_value;
  change_list.push_front(change);
}


void THD::change_item_tree_place(Item **old_ref, Item **new_ref)
{
  I_List_iterator<Item_change_record> it(change_list);
  Item_change_record *change;
  while ((change= it++))
  {
    if (change->place == old_ref)
    {
      DBUG_PRINT("info", ("change_item_tree_place old_ref %p new_ref %p",
                          old_ref, new_ref));
      change->place= new_ref;
      break;
    }
  }
}


void THD::rollback_item_tree_changes()
{
  I_List_iterator<Item_change_record> it(change_list);
  Item_change_record *change;
  DBUG_ENTER("rollback_item_tree_changes");

  while ((change= it++))
  {
    DBUG_PRINT("info",
               ("rollback_item_tree_changes "
                "place %p curr_value %p old_value %p",
                change->place, *change->place, change->old_value));
    *change->place= change->old_value;
  }
  /* We can forget about changes memory: it's allocated in runtime memroot */
  change_list.empty();
  DBUG_VOID_RETURN;
}


/*****************************************************************************
** Functions to provide a interface to select results
*****************************************************************************/

select_result::select_result():
  estimated_rowcount(0)
{
  thd=current_thd;
}

void select_result::send_error(uint errcode,const char *err)
{
  my_message(errcode, err, MYF(0));
}


void select_result::cleanup()
{
  /* do nothing */
}

bool select_result::check_simple_select() const
{
  my_error(ER_SP_BAD_CURSOR_QUERY, MYF(0));
  return TRUE;
}


static const String default_line_term("\n",default_charset_info);
static const String default_escaped("\\",default_charset_info);
static const String default_field_term("\t",default_charset_info);
static const String default_xml_row_term("<row>", default_charset_info);
static const String my_empty_string("",default_charset_info);


sql_exchange::sql_exchange(char *name, bool flag,
                           enum enum_filetype filetype_arg)
  :file_name(name), opt_enclosed(0), dumpfile(flag), skip_lines(0)
{
  filetype= filetype_arg;
  field_term= &default_field_term;
  enclosed=   line_start= &my_empty_string;
  line_term=  filetype == FILETYPE_CSV ?
              &default_line_term : &default_xml_row_term;
  escaped=    &default_escaped;
  cs= NULL;
}

bool sql_exchange::escaped_given(void)
{
  return escaped != &default_escaped;
}


bool select_send::send_result_set_metadata(List<Item> &list, uint flags)
{
  bool res;
  if (!(res= thd->protocol->send_result_set_metadata(&list, flags)))
    is_result_set_started= 1;
  return res;
}

void select_send::abort_result_set()
{
  DBUG_ENTER("select_send::abort_result_set");

  if (is_result_set_started && thd->sp_runtime_ctx)
  {
    /*
      We're executing a stored procedure, have an open result
      set and an SQL exception condition. In this situation we
      must abort the current statement, silence the error and
      start executing the continue/exit handler if one is found.
      Before aborting the statement, let's end the open result set, as
      otherwise the client will hang due to the violation of the
      client/server protocol.
    */
    thd->sp_runtime_ctx->end_partial_result_set= TRUE;
  }
  DBUG_VOID_RETURN;
}


void select_send::cleanup()
{
  is_result_set_started= FALSE;
}

/* Send data to client. Returns 0 if ok */

bool select_send::send_data(List<Item> &items)
{
  Protocol *protocol= thd->protocol;
  DBUG_ENTER("select_send::send_data");

  if (unit->offset_limit_cnt)
  {                                             // using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(FALSE);
  }

  /*
    We may be passing the control from mysqld to the client: release the
    InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved
    by thd
  */
  ha_release_temporary_latches(thd);

  protocol->prepare_for_resend();
  if (protocol->send_result_set_row(&items))
  {
    protocol->remove_last_row();
    DBUG_RETURN(TRUE);
  }

  thd->inc_sent_row_count(1);

  if (thd->vio_ok())
    DBUG_RETURN(protocol->write());

  DBUG_RETURN(0);
}

bool select_send::send_eof()
{
  /* 
    We may be passing the control from mysqld to the client: release the
    InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved
    by thd 
  */
  ha_release_temporary_latches(thd);

  /* 
    Don't send EOF if we're in error condition (which implies we've already
    sent or are sending an error)
  */
  if (thd->is_error())
    return TRUE;
  ::my_eof(thd);
  is_result_set_started= 0;
  return FALSE;
}


/************************************************************************
  Handling writing to file
************************************************************************/

void select_to_file::send_error(uint errcode,const char *err)
{
  my_message(errcode, err, MYF(0));
  if (file > 0)
  {
    (void) end_io_cache(&cache);
    mysql_file_close(file, MYF(0));
    /* Delete file on error */
    mysql_file_delete(key_select_to_file, path, MYF(0));
    file= -1;
  }
}


bool select_to_file::send_eof()
{
  int error= test(end_io_cache(&cache));
  if (mysql_file_close(file, MYF(MY_WME)) || thd->is_error())
    error= true;

  if (!error)
  {
    ::my_ok(thd,row_count);
  }
  file= -1;
  return error;
}


void select_to_file::cleanup()
{
  /* In case of error send_eof() may be not called: close the file here. */
  if (file >= 0)
  {
    (void) end_io_cache(&cache);
    mysql_file_close(file, MYF(0));
    file= -1;
  }
  path[0]= '\0';
  row_count= 0;
}


select_to_file::~select_to_file()
{
  if (file >= 0)
  {                                     // This only happens in case of error
    (void) end_io_cache(&cache);
    mysql_file_close(file, MYF(0));
    file= -1;
  }
}

/***************************************************************************
** Export of select to textfile
***************************************************************************/

select_export::~select_export()
{
  thd->set_sent_row_count(row_count);
}


/*
  Create file with IO cache

  SYNOPSIS
    create_file()
    thd                 Thread handle
    path                File name
    exchange            Excange class
    cache               IO cache

  RETURN
    >= 0        File handle
   -1           Error
*/


static File create_file(THD *thd, char *path, sql_exchange *exchange,
                        IO_CACHE *cache)
{
  File file;
  uint option= MY_UNPACK_FILENAME | MY_RELATIVE_PATH;

#ifdef DONT_ALLOW_FULL_LOAD_DATA_PATHS
  option|= MY_REPLACE_DIR;                      // Force use of db directory
#endif

  if (!dirname_length(exchange->file_name))
  {
    strxnmov(path, FN_REFLEN-1, mysql_real_data_home, thd->db ? thd->db : "",
             NullS);
    (void) fn_format(path, exchange->file_name, path, "", option);
  }
  else
    (void) fn_format(path, exchange->file_name, mysql_real_data_home, "", option);

  if (!is_secure_file_path(path))
  {
    /* Write only allowed to dir or subdir specified by secure_file_priv */
    my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--secure-file-priv");
    return -1;
  }

  if (!access(path, F_OK))
  {
    my_error(ER_FILE_EXISTS_ERROR, MYF(0), exchange->file_name);
    return -1;
  }
  /* Create the file world readable */
  if ((file= mysql_file_create(key_select_to_file,
                               path, 0666, O_WRONLY|O_EXCL, MYF(MY_WME))) < 0)
    return file;
#ifdef HAVE_FCHMOD
  (void) fchmod(file, 0666);                    // Because of umask()
#else
  (void) chmod(path, 0666);
#endif
  if (init_io_cache(cache, file, 0L, WRITE_CACHE, 0L, 1, MYF(MY_WME)))
  {
    mysql_file_close(file, MYF(0));
    /* Delete file on error, it was just created */
    mysql_file_delete(key_select_to_file, path, MYF(0));
    return -1;
  }
  return file;
}


int
select_export::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
{
  bool blob_flag=0;
  bool string_results= FALSE, non_string_results= FALSE;
  unit= u;
  if ((uint) strlen(exchange->file_name) + NAME_LEN >= FN_REFLEN)
    strmake(path,exchange->file_name,FN_REFLEN-1);

  write_cs= exchange->cs ? exchange->cs : &my_charset_bin;

  if ((file= create_file(thd, path, exchange, &cache)) < 0)
    return 1;
  /* Check if there is any blobs in data */
  {
    List_iterator_fast<Item> li(list);
    Item *item;
    while ((item=li++))
    {
      if (item->max_length >= MAX_BLOB_WIDTH)
      {
        blob_flag=1;
        break;
      }
      if (item->result_type() == STRING_RESULT)
        string_results= TRUE;
      else
        non_string_results= TRUE;
    }
  }
  if (exchange->escaped->numchars() > 1 || exchange->enclosed->numchars() > 1)
  {
    my_error(ER_WRONG_FIELD_TERMINATORS, MYF(0));
    return TRUE;
  }
  if (exchange->escaped->length() > 1 || exchange->enclosed->length() > 1 ||
      !my_isascii(exchange->escaped->ptr()[0]) ||
      !my_isascii(exchange->enclosed->ptr()[0]) ||
      !exchange->field_term->is_ascii() || !exchange->line_term->is_ascii() ||
      !exchange->line_start->is_ascii())
  {
    /*
      Current LOAD DATA INFILE recognizes field/line separators "as is" without
      converting from client charset to data file charset. So, it is supposed,
      that input file of LOAD DATA INFILE consists of data in one charset and
      separators in other charset. For the compatibility with that [buggy]
      behaviour SELECT INTO OUTFILE implementation has been saved "as is" too,
      but the new warning message has been added:

        Non-ASCII separator arguments are not fully supported
    */
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                 WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED,
                 ER(WARN_NON_ASCII_SEPARATOR_NOT_IMPLEMENTED));
  }
  field_term_length=exchange->field_term->length();
  field_term_char= field_term_length ?
                   (int) (uchar) (*exchange->field_term)[0] : INT_MAX;
  if (!exchange->line_term->length())
    exchange->line_term=exchange->field_term;   // Use this if it exists
  field_sep_char= (exchange->enclosed->length() ?
                  (int) (uchar) (*exchange->enclosed)[0] : field_term_char);
  if (exchange->escaped->length() && (exchange->escaped_given() ||
      !(thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES)))
    escape_char= (int) (uchar) (*exchange->escaped)[0];
  else
    escape_char= -1;
  is_ambiguous_field_sep= test(strchr(ESCAPE_CHARS, field_sep_char));
  is_unsafe_field_sep= test(strchr(NUMERIC_CHARS, field_sep_char));
  line_sep_char= (exchange->line_term->length() ?
                 (int) (uchar) (*exchange->line_term)[0] : INT_MAX);
  if (!field_term_length)
    exchange->opt_enclosed=0;
  if (!exchange->enclosed->length())
    exchange->opt_enclosed=1;                   // A little quicker loop
  fixed_row_size= (!field_term_length && !exchange->enclosed->length() &&
                   !blob_flag);
  if ((is_ambiguous_field_sep && exchange->enclosed->is_empty() &&
       (string_results || is_unsafe_field_sep)) ||
      (exchange->opt_enclosed && non_string_results &&
       field_term_length && strchr(NUMERIC_CHARS, field_term_char)))
  {
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                 ER_AMBIGUOUS_FIELD_TERM, ER(ER_AMBIGUOUS_FIELD_TERM));
    is_ambiguous_field_term= TRUE;
  }
  else
    is_ambiguous_field_term= FALSE;

  return 0;
}


#define NEED_ESCAPING(x) ((int) (uchar) (x) == escape_char    || \
                          (enclosed ? (int) (uchar) (x) == field_sep_char      \
                                    : (int) (uchar) (x) == field_term_char) || \
                          (int) (uchar) (x) == line_sep_char  || \
                          !(x))

bool select_export::send_data(List<Item> &items)
{

  DBUG_ENTER("select_export::send_data");
  char buff[MAX_FIELD_WIDTH],null_buff[2],space[MAX_FIELD_WIDTH];
  char cvt_buff[MAX_FIELD_WIDTH];
  String cvt_str(cvt_buff, sizeof(cvt_buff), write_cs);
  bool space_inited=0;
  String tmp(buff,sizeof(buff),&my_charset_bin),*res;
  tmp.length(0);

  if (unit->offset_limit_cnt)
  {                                             // using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(0);
  }
  row_count++;
  Item *item;
  uint used_length=0,items_left=items.elements;
  List_iterator_fast<Item> li(items);

  if (my_b_write(&cache,(uchar*) exchange->line_start->ptr(),
                 exchange->line_start->length()))
    goto err;
  while ((item=li++))
  {
    Item_result result_type=item->result_type();
    bool enclosed = (exchange->enclosed->length() &&
                     (!exchange->opt_enclosed || result_type == STRING_RESULT));
    res=item->str_result(&tmp);
    if (res && !my_charset_same(write_cs, res->charset()) &&
        !my_charset_same(write_cs, &my_charset_bin))
    {
      const char *well_formed_error_pos;
      const char *cannot_convert_error_pos;
      const char *from_end_pos;
      const char *error_pos;
      uint32 bytes;
      uint64 estimated_bytes=
        ((uint64) res->length() / res->charset()->mbminlen + 1) *
        write_cs->mbmaxlen + 1;
      set_if_smaller(estimated_bytes, UINT_MAX32);
      if (cvt_str.realloc((uint32) estimated_bytes))
      {
        my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), (uint32) estimated_bytes);
        goto err;
      }

      bytes= well_formed_copy_nchars(write_cs, (char *) cvt_str.ptr(),
                                     cvt_str.alloced_length(),
                                     res->charset(), res->ptr(), res->length(),
                                     UINT_MAX32, // copy all input chars,
                                                 // i.e. ignore nchars parameter
                                     &well_formed_error_pos,
                                     &cannot_convert_error_pos,
                                     &from_end_pos);
      error_pos= well_formed_error_pos ? well_formed_error_pos
                                       : cannot_convert_error_pos;
      if (error_pos)
      {
        char printable_buff[32];
        convert_to_printable(printable_buff, sizeof(printable_buff),
                             error_pos, res->ptr() + res->length() - error_pos,
                             res->charset(), 6);
        push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                            ER_TRUNCATED_WRONG_VALUE_FOR_FIELD,
                            ER(ER_TRUNCATED_WRONG_VALUE_FOR_FIELD),
                            "string", printable_buff,
                            item->item_name.ptr(), static_cast<long>(row_count));
      }
      else if (from_end_pos < res->ptr() + res->length())
      { 
        /*
          result is longer than UINT_MAX32 and doesn't fit into String
        */
        push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                            WARN_DATA_TRUNCATED, ER(WARN_DATA_TRUNCATED),
                            item->full_name(), static_cast<long>(row_count));
      }
      cvt_str.length(bytes);
      res= &cvt_str;
    }
    if (res && enclosed)
    {
      if (my_b_write(&cache,(uchar*) exchange->enclosed->ptr(),
                     exchange->enclosed->length()))
        goto err;
    }
    if (!res)
    {                                           // NULL
      if (!fixed_row_size)
      {
        if (escape_char != -1)                  // Use \N syntax
        {
          null_buff[0]=escape_char;
          null_buff[1]='N';
          if (my_b_write(&cache,(uchar*) null_buff,2))
            goto err;
        }
        else if (my_b_write(&cache,(uchar*) "NULL",4))
          goto err;
      }
      else
      {
        used_length=0;                          // Fill with space
      }
    }
    else
    {
      if (fixed_row_size)
        used_length=min(res->length(),item->max_length);
      else
        used_length=res->length();
      if ((result_type == STRING_RESULT || is_unsafe_field_sep) &&
           escape_char != -1)
      {
        char *pos, *start, *end;
        const CHARSET_INFO *res_charset= res->charset();
        const CHARSET_INFO *character_set_client=
          thd->variables.character_set_client;
        bool check_second_byte= (res_charset == &my_charset_bin) &&
                                 character_set_client->
                                 escape_with_backslash_is_dangerous;
        DBUG_ASSERT(character_set_client->mbmaxlen == 2 ||
                    !character_set_client->escape_with_backslash_is_dangerous);
        for (start=pos=(char*) res->ptr(),end=pos+used_length ;
             pos != end ;
             pos++)
        {
#ifdef USE_MB
          if (use_mb(res_charset))
          {
            int l;
            if ((l=my_ismbchar(res_charset, pos, end)))
            {
              pos += l-1;
              continue;
            }
          }
#endif

          /*
            Special case when dumping BINARY/VARBINARY/BLOB values
            for the clients with character sets big5, cp932, gbk and sjis,
            which can have the escape character (0x5C "\" by default)
            as the second byte of a multi-byte sequence.
            
            If
            - pos[0] is a valid multi-byte head (e.g 0xEE) and
            - pos[1] is 0x00, which will be escaped as "\0",
            
            then we'll get "0xEE + 0x5C + 0x30" in the output file.
            
            If this file is later loaded using this sequence of commands:
            
            mysql> create table t1 (a varchar(128)) character set big5;
            mysql> LOAD DATA INFILE 'dump.txt' INTO TABLE t1;
            
            then 0x5C will be misinterpreted as the second byte
            of a multi-byte character "0xEE + 0x5C", instead of
            escape character for 0x00.
            
            To avoid this confusion, we'll escape the multi-byte
            head character too, so the sequence "0xEE + 0x00" will be
            dumped as "0x5C + 0xEE + 0x5C + 0x30".
            
            Note, in the condition below we only check if
            mbcharlen is equal to 2, because there are no
            character sets with mbmaxlen longer than 2
            and with escape_with_backslash_is_dangerous set.
            DBUG_ASSERT before the loop makes that sure.
          */

          if ((NEED_ESCAPING(*pos) ||
               (check_second_byte &&
                my_mbcharlen(character_set_client, (uchar) *pos) == 2 &&
                pos + 1 < end &&
                NEED_ESCAPING(pos[1]))) &&
              /*
               Don't escape field_term_char by doubling - doubling is only
               valid for ENCLOSED BY characters:
              */
              (enclosed || !is_ambiguous_field_term ||
               (int) (uchar) *pos != field_term_char))
          {
            char tmp_buff[2];
            tmp_buff[0]= ((int) (uchar) *pos == field_sep_char &&
                          is_ambiguous_field_sep) ?
                          field_sep_char : escape_char;
            tmp_buff[1]= *pos ? *pos : '0';
            if (my_b_write(&cache,(uchar*) start,(uint) (pos-start)) ||
                my_b_write(&cache,(uchar*) tmp_buff,2))
              goto err;
            start=pos+1;
          }
        }
        if (my_b_write(&cache,(uchar*) start,(uint) (pos-start)))
          goto err;
      }
      else if (my_b_write(&cache,(uchar*) res->ptr(),used_length))
        goto err;
    }
    if (fixed_row_size)
    {                                           // Fill with space
      if (item->max_length > used_length)
      {
        /* QQ:  Fix by adding a my_b_fill() function */
        if (!space_inited)
        {
          space_inited=1;
          memset(space, ' ', sizeof(space));
        }
        uint length=item->max_length-used_length;
        for (; length > sizeof(space) ; length-=sizeof(space))
        {
          if (my_b_write(&cache,(uchar*) space,sizeof(space)))
            goto err;
        }
        if (my_b_write(&cache,(uchar*) space,length))
          goto err;
      }
    }
    if (res && enclosed)
    {
      if (my_b_write(&cache, (uchar*) exchange->enclosed->ptr(),
                     exchange->enclosed->length()))
        goto err;
    }
    if (--items_left)
    {
      if (my_b_write(&cache, (uchar*) exchange->field_term->ptr(),
                     field_term_length))
        goto err;
    }
  }
  if (my_b_write(&cache,(uchar*) exchange->line_term->ptr(),
                 exchange->line_term->length()))
    goto err;
  DBUG_RETURN(0);
err:
  DBUG_RETURN(1);
}


/***************************************************************************
** Dump  of select to a binary file
***************************************************************************/


int
select_dump::prepare(List<Item> &list __attribute__((unused)),
                     SELECT_LEX_UNIT *u)
{
  unit= u;
  return (int) ((file= create_file(thd, path, exchange, &cache)) < 0);
}


bool select_dump::send_data(List<Item> &items)
{
  List_iterator_fast<Item> li(items);
  char buff[MAX_FIELD_WIDTH];
  String tmp(buff,sizeof(buff),&my_charset_bin),*res;
  tmp.length(0);
  Item *item;
  DBUG_ENTER("select_dump::send_data");

  if (unit->offset_limit_cnt)
  {                                             // using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(0);
  }
  if (row_count++ > 1) 
  {
    my_message(ER_TOO_MANY_ROWS, ER(ER_TOO_MANY_ROWS), MYF(0));
    goto err;
  }
  while ((item=li++))
  {
    res=item->str_result(&tmp);
    if (!res)                                   // If NULL
    {
      if (my_b_write(&cache,(uchar*) "",1))
        goto err;
    }
    else if (my_b_write(&cache,(uchar*) res->ptr(),res->length()))
    {
      char errbuf[MYSYS_STRERROR_SIZE];
      my_error(ER_ERROR_ON_WRITE, MYF(0), path, my_errno,
               my_strerror(errbuf, sizeof(errbuf), my_errno));
      goto err;
    }
  }
  DBUG_RETURN(0);
err:
  DBUG_RETURN(1);
}


select_subselect::select_subselect(Item_subselect *item_arg)
{
  item= item_arg;
}


bool select_singlerow_subselect::send_data(List<Item> &items)
{
  DBUG_ENTER("select_singlerow_subselect::send_data");
  Item_singlerow_subselect *it= (Item_singlerow_subselect *)item;
  if (it->assigned())
  {
    my_message(ER_SUBQUERY_NO_1_ROW, ER(ER_SUBQUERY_NO_1_ROW), MYF(0));
    DBUG_RETURN(1);
  }
  if (unit->offset_limit_cnt)
  {                                       // Using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(0);
  }
  List_iterator_fast<Item> li(items);
  Item *val_item;
  for (uint i= 0; (val_item= li++); i++)
    it->store(i, val_item);
  it->assigned(1);
  DBUG_RETURN(0);
}


void select_max_min_finder_subselect::cleanup()
{
  DBUG_ENTER("select_max_min_finder_subselect::cleanup");
  cache= 0;
  DBUG_VOID_RETURN;
}


bool select_max_min_finder_subselect::send_data(List<Item> &items)
{
  DBUG_ENTER("select_max_min_finder_subselect::send_data");
  Item_maxmin_subselect *it= (Item_maxmin_subselect *)item;
  List_iterator_fast<Item> li(items);
  Item *val_item= li++;
  it->register_value();
  if (it->assigned())
  {
    cache->store(val_item);
    if ((this->*op)())
      it->store(0, cache);
  }
  else
  {
    if (!cache)
    {
      cache= Item_cache::get_cache(val_item);
      switch (val_item->result_type())
      {
      case REAL_RESULT:
        op= &select_max_min_finder_subselect::cmp_real;
        break;
      case INT_RESULT:
        op= &select_max_min_finder_subselect::cmp_int;
        break;
      case STRING_RESULT:
        op= &select_max_min_finder_subselect::cmp_str;
        break;
      case DECIMAL_RESULT:
        op= &select_max_min_finder_subselect::cmp_decimal;
        break;
      case ROW_RESULT:
        // This case should never be choosen
        DBUG_ASSERT(0);
        op= 0;
      }
    }
    cache->store(val_item);
    it->store(0, cache);
  }
  it->assigned(1);
  DBUG_RETURN(0);
}

bool select_max_min_finder_subselect::cmp_real()
{
  Item *maxmin= ((Item_singlerow_subselect *)item)->element_index(0);
  double val1= cache->val_real(), val2= maxmin->val_real();
  /*
    If we're ignoring NULLs and the current maximum/minimum is NULL
    (must have been placed there as the first value iterated over) and
    the new value is not NULL, return true so that a new, non-NULL
    maximum/minimum is set. Otherwise, return false to keep the
    current non-NULL maximum/minimum.

    If we're not ignoring NULLs and the current maximum/minimum is not
    NULL, return true to store NULL. Otherwise, return false to keep
    the NULL we've already got.
  */
  if (cache->null_value || maxmin->null_value)
    return (ignore_nulls) ? !(cache->null_value) : !(maxmin->null_value);
  return (fmax) ? (val1 > val2) : (val1 < val2);
}

bool select_max_min_finder_subselect::cmp_int()
{
  Item *maxmin= ((Item_singlerow_subselect *)item)->element_index(0);
  longlong val1= cache->val_int(), val2= maxmin->val_int();
  if (cache->null_value || maxmin->null_value)
    return (ignore_nulls) ? !(cache->null_value) : !(maxmin->null_value);
  return (fmax) ? (val1 > val2) : (val1 < val2);
}

bool select_max_min_finder_subselect::cmp_decimal()
{
  Item *maxmin= ((Item_singlerow_subselect *)item)->element_index(0);
  my_decimal cval, *cvalue= cache->val_decimal(&cval);
  my_decimal mval, *mvalue= maxmin->val_decimal(&mval);
  if (cache->null_value || maxmin->null_value)
    return (ignore_nulls) ? !(cache->null_value) : !(maxmin->null_value);
  return (fmax) 
    ? (my_decimal_cmp(cvalue,mvalue) > 0)
    : (my_decimal_cmp(cvalue,mvalue) < 0);
}

bool select_max_min_finder_subselect::cmp_str()
{
  String *val1, *val2, buf1, buf2;
  Item *maxmin= ((Item_singlerow_subselect *)item)->element_index(0);
  /*
    as far as both operand is Item_cache buf1 & buf2 will not be used,
    but added for safety
  */
  val1= cache->val_str(&buf1);
  val2= maxmin->val_str(&buf1);
  if (cache->null_value || maxmin->null_value)
    return (ignore_nulls) ? !(cache->null_value) : !(maxmin->null_value);
  return (fmax) 
    ? (sortcmp(val1, val2, cache->collation.collation) > 0)
    : (sortcmp(val1, val2, cache->collation.collation) < 0);
}

bool select_exists_subselect::send_data(List<Item> &items)
{
  DBUG_ENTER("select_exists_subselect::send_data");
  Item_exists_subselect *it= (Item_exists_subselect *)item;
  if (unit->offset_limit_cnt)
  {                                       // Using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(0);
  }
  /*
    A subquery may be evaluated 1) by executing the JOIN 2) by optimized
    functions (index_subquery, subquery materialization).
    It's only in (1) that we get here when we find a row. In (2) "value" is
    set elsewhere.
  */
  it->value= 1;
  it->assigned(1);
  DBUG_RETURN(0);
}


/***************************************************************************
  Dump of select to variables
***************************************************************************/

int select_dumpvar::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
{
  unit= u;

  if (var_list.elements != list.elements)
  {
    my_message(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,
               ER(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT), MYF(0));
    return 1;
  }

  return 0;
}


bool select_dumpvar::check_simple_select() const
{
  my_error(ER_SP_BAD_CURSOR_SELECT, MYF(0));
  return TRUE;
}


void select_dumpvar::cleanup()
{
  row_count= 0;
}


Query_arena::Type Query_arena::type() const
{
  DBUG_ASSERT(0); /* Should never be called */
  return STATEMENT;
}


void Query_arena::free_items()
{
  Item *next;
  DBUG_ENTER("Query_arena::free_items");
  /* This works because items are allocated with sql_alloc() */
  for (; free_list; free_list= next)
  {
    next= free_list->next;
    free_list->delete_self();
  }
  /* Postcondition: free_list is 0 */
  DBUG_VOID_RETURN;
}


void Query_arena::set_query_arena(Query_arena *set)
{
  mem_root=  set->mem_root;
  free_list= set->free_list;
  state= set->state;
}


void Query_arena::cleanup_stmt()
{
  DBUG_ASSERT(! "Query_arena::cleanup_stmt() not implemented");
}

/*
  Statement functions
*/

Statement::Statement(LEX *lex_arg, MEM_ROOT *mem_root_arg,
                     enum enum_state state_arg, ulong id_arg)
  :Query_arena(mem_root_arg, state_arg),
  id(id_arg),
  mark_used_columns(MARK_COLUMNS_READ),
  lex(lex_arg),
  db(NULL),
  db_length(0)
{
  name.str= NULL;
}


Query_arena::Type Statement::type() const
{
  return STATEMENT;
}


void Statement::set_statement(Statement *stmt)
{
  id=             stmt->id;
  mark_used_columns=   stmt->mark_used_columns;
  lex=            stmt->lex;
  query_string=   stmt->query_string;
}


void
Statement::set_n_backup_statement(Statement *stmt, Statement *backup)
{
  DBUG_ENTER("Statement::set_n_backup_statement");
  backup->set_statement(this);
  set_statement(stmt);
  DBUG_VOID_RETURN;
}


void Statement::restore_backup_statement(Statement *stmt, Statement *backup)
{
  DBUG_ENTER("Statement::restore_backup_statement");
  stmt->set_statement(this);
  set_statement(backup);
  DBUG_VOID_RETURN;
}


void THD::end_statement()
{
  /* Cleanup SQL processing state to reuse this statement in next query. */
  lex_end(lex);
  delete lex->result;
  lex->result= 0;
  /* Note that free_list is freed in cleanup_after_query() */

  /*
    Don't free mem_root, as mem_root is freed in the end of dispatch_command
    (once for any command).
  */
}


void THD::set_n_backup_active_arena(Query_arena *set, Query_arena *backup)
{
  DBUG_ENTER("THD::set_n_backup_active_arena");
  DBUG_ASSERT(backup->is_backup_arena == FALSE);

  backup->set_query_arena(this);
  set_query_arena(set);
#ifndef DBUG_OFF
  backup->is_backup_arena= TRUE;
#endif
  DBUG_VOID_RETURN;
}


void THD::restore_active_arena(Query_arena *set, Query_arena *backup)
{
  DBUG_ENTER("THD::restore_active_arena");
  DBUG_ASSERT(backup->is_backup_arena);
  set->set_query_arena(this);
  set_query_arena(backup);
#ifndef DBUG_OFF
  backup->is_backup_arena= FALSE;
#endif
  DBUG_VOID_RETURN;
}

Statement::~Statement()
{
}

C_MODE_START

static uchar *
get_statement_id_as_hash_key(const uchar *record, size_t *key_length,
                             my_bool not_used __attribute__((unused)))
{
  const Statement *statement= (const Statement *) record; 
  *key_length= sizeof(statement->id);
  return (uchar *) &((const Statement *) statement)->id;
}

static void delete_statement_as_hash_key(void *key)
{
  delete (Statement *) key;
}

static uchar *get_stmt_name_hash_key(Statement *entry, size_t *length,
                                    my_bool not_used __attribute__((unused)))
{
  *length= entry->name.length;
  return (uchar*) entry->name.str;
}

C_MODE_END

Statement_map::Statement_map() :
  last_found_statement(0)
{
  enum
  {
    START_STMT_HASH_SIZE = 16,
    START_NAME_HASH_SIZE = 16
  };
  my_hash_init(&st_hash, &my_charset_bin, START_STMT_HASH_SIZE, 0, 0,
               get_statement_id_as_hash_key,
               delete_statement_as_hash_key, MYF(0));
  my_hash_init(&names_hash, system_charset_info, START_NAME_HASH_SIZE, 0, 0,
               (my_hash_get_key) get_stmt_name_hash_key,
               NULL,MYF(0));
}


/*
  Insert a new statement to the thread-local statement map.

  DESCRIPTION
    If there was an old statement with the same name, replace it with the
    new one. Otherwise, check if max_prepared_stmt_count is not reached yet,
    increase prepared_stmt_count, and insert the new statement. It's okay
    to delete an old statement and fail to insert the new one.

  POSTCONDITIONS
    All named prepared statements are also present in names_hash.
    Statement names in names_hash are unique.
    The statement is added only if prepared_stmt_count < max_prepard_stmt_count
    last_found_statement always points to a valid statement or is 0

  RETURN VALUE
    0  success
    1  error: out of resources or max_prepared_stmt_count limit has been
       reached. An error is sent to the client, the statement is deleted.
*/

int Statement_map::insert(THD *thd, Statement *statement)
{
  if (my_hash_insert(&st_hash, (uchar*) statement))
  {
    /*
      Delete is needed only in case of an insert failure. In all other
      cases hash_delete will also delete the statement.
    */
    delete statement;
    my_error(ER_OUT_OF_RESOURCES, MYF(0));
    goto err_st_hash;
  }
  if (statement->name.str && my_hash_insert(&names_hash, (uchar*) statement))
  {
    my_error(ER_OUT_OF_RESOURCES, MYF(0));
    goto err_names_hash;
  }
  mysql_mutex_lock(&LOCK_prepared_stmt_count);
  /*
    We don't check that prepared_stmt_count is <= max_prepared_stmt_count
    because we would like to allow to lower the total limit
    of prepared statements below the current count. In that case
    no new statements can be added until prepared_stmt_count drops below
    the limit.
  */
  if (prepared_stmt_count >= max_prepared_stmt_count)
  {
    mysql_mutex_unlock(&LOCK_prepared_stmt_count);
    my_error(ER_MAX_PREPARED_STMT_COUNT_REACHED, MYF(0),
             max_prepared_stmt_count);
    goto err_max;
  }
  prepared_stmt_count++;
  mysql_mutex_unlock(&LOCK_prepared_stmt_count);

  last_found_statement= statement;
  return 0;

err_max:
  if (statement->name.str)
    my_hash_delete(&names_hash, (uchar*) statement);
err_names_hash:
  my_hash_delete(&st_hash, (uchar*) statement);
err_st_hash:
  return 1;
}


void Statement_map::close_transient_cursors()
{
#ifdef TO_BE_IMPLEMENTED
  Statement *stmt;
  while ((stmt= transient_cursor_list.head()))
    stmt->close_cursor();                 /* deletes itself from the list */
#endif
}


void Statement_map::erase(Statement *statement)
{
  if (statement == last_found_statement)
    last_found_statement= 0;
  if (statement->name.str)
    my_hash_delete(&names_hash, (uchar *) statement);

  my_hash_delete(&st_hash, (uchar *) statement);
  mysql_mutex_lock(&LOCK_prepared_stmt_count);
  DBUG_ASSERT(prepared_stmt_count > 0);
  prepared_stmt_count--;
  mysql_mutex_unlock(&LOCK_prepared_stmt_count);
}


void Statement_map::reset()
{
  /* Must be first, hash_free will reset st_hash.records */
  mysql_mutex_lock(&LOCK_prepared_stmt_count);
  DBUG_ASSERT(prepared_stmt_count >= st_hash.records);
  prepared_stmt_count-= st_hash.records;
  mysql_mutex_unlock(&LOCK_prepared_stmt_count);

  my_hash_reset(&names_hash);
  my_hash_reset(&st_hash);
  last_found_statement= 0;
}


Statement_map::~Statement_map()
{
  /*
    We do not want to grab the global LOCK_prepared_stmt_count mutex here.
    reset() should already have been called to maintain prepared_stmt_count.
   */
  DBUG_ASSERT(st_hash.records == 0);

  my_hash_free(&names_hash);
  my_hash_free(&st_hash);
}

bool select_dumpvar::send_data(List<Item> &items)
{
  List_iterator_fast<my_var> var_li(var_list);
  List_iterator<Item> it(items);
  Item *item;
  my_var *mv;
  DBUG_ENTER("select_dumpvar::send_data");

  if (unit->offset_limit_cnt)
  {                                             // using limit offset,count
    unit->offset_limit_cnt--;
    DBUG_RETURN(false);
  }
  if (row_count++) 
  {
    my_message(ER_TOO_MANY_ROWS, ER(ER_TOO_MANY_ROWS), MYF(0));
    DBUG_RETURN(true);
  }
  while ((mv= var_li++) && (item= it++))
  {
    if (mv->local)
    {
      if (thd->sp_runtime_ctx->set_variable(thd, mv->offset, &item))
            DBUG_RETURN(true);
    }
    else
    {
      /*
        Create Item_func_set_user_vars with delayed non-constness. We
        do this so that Item_get_user_var::const_item() will return
        the same result during
        Item_func_set_user_var::save_item_result() as they did during
        optimization and execution.
       */
      Item_func_set_user_var *suv=
        new Item_func_set_user_var(mv->s, item, true);
      if (suv->fix_fields(thd, 0))
        DBUG_RETURN(true);
      suv->save_item_result(item);
      if (suv->update())
        DBUG_RETURN(true);
    }
  }
  DBUG_RETURN(thd->is_error());
}

bool select_dumpvar::send_eof()
{
  if (! row_count)
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
                 ER_SP_FETCH_NO_DATA, ER(ER_SP_FETCH_NO_DATA));
  /*
    Don't send EOF if we're in error condition (which implies we've already
    sent or are sending an error)
  */
  if (thd->is_error())
    return true;

  ::my_ok(thd,row_count);
  return 0;
}

/****************************************************************************
  TMP_TABLE_PARAM
****************************************************************************/

void TMP_TABLE_PARAM::init()
{
  DBUG_ENTER("TMP_TABLE_PARAM::init");
  DBUG_PRINT("enter", ("this: 0x%lx", (ulong)this));
  field_count= sum_func_count= func_count= hidden_field_count= 0;
  group_parts= group_length= group_null_parts= 0;
  quick_group= 1;
  table_charset= 0;
  precomputed_group_by= 0;
  skip_create_table= 0;
  bit_fields_as_long= 0;
  recinfo= 0;
  start_recinfo= 0;
  keyinfo= 0;
  DBUG_VOID_RETURN;
}


void thd_increment_bytes_sent(ulong length)
{
  THD *thd=current_thd;
  if (likely(thd != 0))
  { /* current_thd==0 when close_connection() calls net_send_error() */
    thd->status_var.bytes_sent+= length;
  }
}


void thd_increment_bytes_received(ulong length)
{
  current_thd->status_var.bytes_received+= length;
}


void THD::set_status_var_init()
{
  memset(&status_var, 0, sizeof(status_var));
}


void Security_context::init()
{
  user= 0;
  ip.set("", 0, system_charset_info);
  host.set("", 0, system_charset_info);
  external_user.set("", 0, system_charset_info);
  host_or_ip= "connecting host";
  priv_user[0]= priv_host[0]= proxy_user[0]= '\0';
  master_access= 0;
#ifndef NO_EMBEDDED_ACCESS_CHECKS
  db_access= NO_ACCESS;
#endif
  password_expired= false; 
}

void Security_context::destroy()
{
  if (host.ptr() != my_localhost && host.length())
  {
    char *c= (char *) host.ptr();
    host.set("", 0, system_charset_info);
    my_free(c);
  }

  if (user && user != delayed_user)
  {
    my_free(user);
    user= NULL;
  }

  if (external_user.length())
  {
    char *c= (char *) external_user.ptr();
    external_user.set("", 0, system_charset_info);
    my_free(c);
  }

  if (ip.length())
  {
    char *c= (char *) ip.ptr();
    ip.set("", 0, system_charset_info);
    my_free(c);
  }

}


void Security_context::skip_grants()
{
  /* privileges for the user are unknown everything is allowed */
  host_or_ip= (char *)"";
  master_access= ~NO_ACCESS;
  *priv_user= *priv_host= '\0';
}


bool Security_context::set_user(char *user_arg)
{
  my_free(user);
  user= my_strdup(user_arg, MYF(0));
  return user == 0;
}

String *Security_context::get_host()
{
  return (&host);
}

String *Security_context::get_ip()
{
  return (&ip);
}

String *Security_context::get_external_user()
{
  return (&external_user);
}

void Security_context::set_host(const char *str)
{
  uint len= str ? strlen(str) :  0;
  host.set(str, len, system_charset_info);
}

void Security_context::set_ip(const char *str)
{
  uint len= str ? strlen(str) :  0;
  ip.set(str, len, system_charset_info);
}

void Security_context::set_external_user(const char *str)
{
  uint len= str ? strlen(str) :  0;
  external_user.set(str, len, system_charset_info);
}

void Security_context::set_host(const char * str, size_t len)
{
  host.set(str, len, system_charset_info);
  host.c_ptr_quick();
}

#ifndef NO_EMBEDDED_ACCESS_CHECKS

bool
Security_context::
change_security_context(THD *thd,
                        LEX_STRING *definer_user,
                        LEX_STRING *definer_host,
                        LEX_STRING *db,
                        Security_context **backup)
{
  bool needs_change;

  DBUG_ENTER("Security_context::change_security_context");

  DBUG_ASSERT(definer_user->str && definer_host->str);

  *backup= NULL;
  needs_change= (strcmp(definer_user->str, thd->security_ctx->priv_user) ||
                 my_strcasecmp(system_charset_info, definer_host->str,
                               thd->security_ctx->priv_host));
  if (needs_change)
  {
    if (acl_getroot(this, definer_user->str, definer_host->str,
                                definer_host->str, db->str))
    {
      my_error(ER_NO_SUCH_USER, MYF(0), definer_user->str,
               definer_host->str);
      DBUG_RETURN(TRUE);
    }
    *backup= thd->security_ctx;
    thd->security_ctx= this;
  }

  DBUG_RETURN(FALSE);
}


void
Security_context::restore_security_context(THD *thd,
                                           Security_context *backup)
{
  if (backup)
    thd->security_ctx= backup;
}
#endif


bool Security_context::user_matches(Security_context *them)
{
  return ((user != NULL) && (them->user != NULL) &&
          !strcmp(user, them->user));
}


void Log_throttle::new_window(ulonglong now)
{
  count= 0;
  window_end= now + window_size;
}


void Slow_log_throttle::new_window(ulonglong now)
{
  Log_throttle::new_window(now);
  total_exec_time= 0;
  total_lock_time= 0;
}


Slow_log_throttle::Slow_log_throttle(ulong *threshold, mysql_mutex_t *lock,
                                     ulong window_usecs,
                                     bool (*logger)(THD *, const char *, uint),
                                     const char *msg)
  : Log_throttle(window_usecs, msg), total_exec_time(0), total_lock_time(0),
    rate(threshold), log_summary(logger), LOCK_log_throttle(lock)
{
  aggregate_sctx.init();
}


ulong Log_throttle::prepare_summary(ulong rate)
{
  ulong ret= 0;
  /*
    Previous throttling window is over or rate changed.
    Return the number of lines we throttled.
  */
  if (count > rate)
  {
    ret= count - rate;
    count= 0;                                 // prevent writing it again.
  }

  return ret;
}


void Slow_log_throttle::print_summary(THD *thd, ulong suppressed,
                                      ulonglong print_lock_time,
                                      ulonglong print_exec_time)
{
  /*
    We synthesize these values so the totals in the log will be
    correct (just in case somebody analyses them), even if the
    start/stop times won't be (as they're an aggregate which will
    usually mostly lie within [ window_end - window_size ; window_end ]
  */
  ulonglong save_start_utime=      thd->start_utime;
  ulonglong save_utime_after_lock= thd->utime_after_lock;
  Security_context *save_sctx=     thd->security_ctx;

  char buf[128];

  snprintf(buf, sizeof(buf), summary_template, suppressed);

  mysql_mutex_lock(&thd->LOCK_thd_data);
  thd->start_utime=                thd->current_utime() - print_exec_time;
  thd->utime_after_lock=           thd->start_utime + print_lock_time;
  thd->security_ctx=               (Security_context *) &aggregate_sctx;
  mysql_mutex_unlock(&thd->LOCK_thd_data);

  (*log_summary)(thd, buf, strlen(buf));

  mysql_mutex_lock(&thd->LOCK_thd_data);
  thd->security_ctx    = save_sctx;
  thd->start_utime     = save_start_utime;
  thd->utime_after_lock= save_utime_after_lock;
  mysql_mutex_unlock(&thd->LOCK_thd_data);
}


bool Slow_log_throttle::flush(THD *thd)
{
  // Write summary if we throttled.
  mysql_mutex_lock(LOCK_log_throttle);
  ulonglong print_lock_time=  total_lock_time;
  ulonglong print_exec_time=  total_exec_time;
  ulong     suppressed_count= prepare_summary(*rate);
  mysql_mutex_unlock(LOCK_log_throttle);
  if (suppressed_count > 0)
  {
    print_summary(thd, suppressed_count, print_lock_time, print_exec_time);
    return true;
  }
  return false;
}


bool Slow_log_throttle::log(THD *thd, bool eligible)
{
  bool  suppress_current= false;

  /*
    If throttling is enabled, we might have to write a summary even if
    the current query is not of the type we handle.
  */
  if (*rate > 0)
  {
    mysql_mutex_lock(LOCK_log_throttle);

    ulong     suppressed_count=   0;
    ulonglong print_lock_time=    total_lock_time;
    ulonglong print_exec_time=    total_exec_time;
    ulonglong end_utime_of_query= thd->current_utime();

    /*
      If the window has expired, we'll try to write a summary line.
      The subroutine will know whether we actually need to.
    */
    if (!in_window(end_utime_of_query))
    {
      suppressed_count= prepare_summary(*rate);
      // start new window only if this is the statement type we handle
      if (eligible)
        new_window(end_utime_of_query);
    }
    if (eligible && inc_log_count(*rate))
    {
      /*
        Current query's logging should be suppressed.
        Add its execution time and lock time to totals for the current window.
      */
      total_exec_time += (end_utime_of_query - thd->start_utime);
      total_lock_time += (thd->utime_after_lock - thd->start_utime);
      suppress_current= true;
    }

    mysql_mutex_unlock(LOCK_log_throttle);

    /*
      print_summary() is deferred until after we release the locks to
      avoid congestion. All variables we hand in are local to the caller,
      so things would even be safe if print_summary() hadn't finished by the
      time the next one comes around (60s later at the earliest for now).
      The current design will produce correct data, but does not guarantee
      order (there is a theoretical race condition here where the above
      new_window()/unlock() may enable a different thread to print a warning
      for the new window before the current thread gets to print_summary().
      If the requirements ever change, add a print_lock to the object that
      is held during print_summary(), AND that is briefly locked before
      returning from this function if(eligible && !suppress_current).
      This should ensure correct ordering of summaries with regard to any
      follow-up summaries as well as to any (non-suppressed) warnings (of
      the type we handle) from the next window.
    */
    if (suppressed_count > 0)
      print_summary(thd, suppressed_count, print_lock_time, print_exec_time);
  }

  return suppress_current;
}


bool Error_log_throttle::log(THD *thd)
{
  ulonglong end_utime_of_query= thd->current_utime();

  /*
    If the window has expired, we'll try to write a summary line.
    The subroutine will know whether we actually need to.
  */
  if (!in_window(end_utime_of_query))
  {
    ulong suppressed_count= prepare_summary(1);

    new_window(end_utime_of_query);

    if (suppressed_count > 0)
      print_summary(suppressed_count);
  }

  /*
    If this is a first error in the current window then do not suppress it.
  */
  return inc_log_count(1);
}


bool Error_log_throttle::flush(THD *thd)
{
  // Write summary if we throttled.
  ulong     suppressed_count= prepare_summary(1);
  if (suppressed_count > 0)
  {
    print_summary(suppressed_count);
    return true;
  }
  return false;
}


/****************************************************************************
  Handling of open and locked tables states.

  This is used when we want to open/lock (and then close) some tables when
  we already have a set of tables open and locked. We use these methods for
  access to mysql.proc table to find definitions of stored routines.
****************************************************************************/

void THD::reset_n_backup_open_tables_state(Open_tables_backup *backup)
{
  DBUG_ENTER("reset_n_backup_open_tables_state");
  backup->set_open_tables_state(this);
  backup->mdl_system_tables_svp= mdl_context.mdl_savepoint();
  reset_open_tables_state();
  state_flags|= Open_tables_state::BACKUPS_AVAIL;
  DBUG_VOID_RETURN;
}


void THD::restore_backup_open_tables_state(Open_tables_backup *backup)
{
  DBUG_ENTER("restore_backup_open_tables_state");
  mdl_context.rollback_to_savepoint(backup->mdl_system_tables_svp);
  /*
    Before we will throw away current open tables state we want
    to be sure that it was properly cleaned up.
  */
  DBUG_ASSERT(open_tables == 0 && temporary_tables == 0 &&
              derived_tables == 0 &&
              lock == 0 &&
              locked_tables_mode == LTM_NONE &&
              get_reprepare_observer() == NULL);

  set_open_tables_state(backup);
  DBUG_VOID_RETURN;
}

extern "C" int thd_killed(const MYSQL_THD thd)
{
  return(thd->killed);
}

extern "C" unsigned long thd_get_thread_id(const MYSQL_THD thd)
{
  return((unsigned long)thd->thread_id);
}

extern "C" int thd_allow_batch(MYSQL_THD thd)
{
  if ((thd->variables.option_bits & OPTION_ALLOW_BATCH) ||
      (thd->slave_thread && opt_slave_allow_batching))
    return 1;
  return 0;
}

enum_tx_isolation thd_get_trx_isolation(const MYSQL_THD thd)
{
        return thd->tx_isolation;
}

#ifdef INNODB_COMPATIBILITY_HOOKS
extern "C" const struct charset_info_st *thd_charset(MYSQL_THD thd)
{
  return(thd->charset());
}

extern "C" char **thd_query(MYSQL_THD thd)
{
  return (&thd->query_string.string.str);
}

extern "C" LEX_STRING * thd_query_string (MYSQL_THD thd)
{
  return(&thd->query_string.string);
}

extern "C" int thd_slave_thread(const MYSQL_THD thd)
{
  return(thd->slave_thread);
}

extern "C" int thd_non_transactional_update(const MYSQL_THD thd)
{
  return thd->transaction.all.has_modified_non_trans_table();
}

extern "C" int thd_binlog_format(const MYSQL_THD thd)
{
  if (mysql_bin_log.is_open() && (thd->variables.option_bits & OPTION_BIN_LOG))
    return (int) thd->variables.binlog_format;
  else
    return BINLOG_FORMAT_UNSPEC;
}

extern "C" void thd_mark_transaction_to_rollback(MYSQL_THD thd, bool all)
{
  mark_transaction_to_rollback(thd, all);
}

extern "C" bool thd_binlog_filter_ok(const MYSQL_THD thd)
{
  return binlog_filter->db_ok(thd->db);
}

extern "C" bool thd_sqlcom_can_generate_row_events(const MYSQL_THD thd)
{
  return sqlcom_can_generate_row_events(thd);
}

extern "C" enum durability_properties thd_get_durability_property(const MYSQL_THD thd)
{
  enum durability_properties ret= HA_REGULAR_DURABILITY;
  
  if (thd != NULL)
    ret= thd->durability_property;

  return ret;
}

extern "C" void thd_get_autoinc(const MYSQL_THD thd, ulong* off, ulong* inc)
{
  *off = thd->variables.auto_increment_offset;
  *inc = thd->variables.auto_increment_increment;
}


extern "C" bool thd_is_strict_mode(const MYSQL_THD thd)
{
  return thd->is_strict_mode();
}


#ifndef EMBEDDED_LIBRARY
extern "C" void thd_pool_wait_begin(MYSQL_THD thd, int wait_type);
extern "C" void thd_pool_wait_end(MYSQL_THD thd);

/*
  Interface for MySQL Server, plugins and storage engines to report
  when they are going to sleep/stall.
  
  SYNOPSIS
  thd_wait_begin()
  thd                     Thread object
  wait_type               Type of wait
                          1 -- short wait (e.g. for mutex)
                          2 -- medium wait (e.g. for disk io)
                          3 -- large wait (e.g. for locked row/table)
  NOTES
    This is used by the threadpool to have better knowledge of which
    threads that currently are actively running on CPUs. When a thread
    reports that it's going to sleep/stall, the threadpool scheduler is
    free to start another thread in the pool most likely. The expected wait
    time is simply an indication of how long the wait is expected to
    become, the real wait time could be very different.

  thd_wait_end MUST be called immediately after waking up again.
*/
extern "C" void thd_wait_begin(MYSQL_THD thd, int wait_type)
{
  MYSQL_CALLBACK(thread_scheduler, thd_wait_begin, (thd, wait_type));
}

extern "C" void thd_wait_end(MYSQL_THD thd)
{
  MYSQL_CALLBACK(thread_scheduler, thd_wait_end, (thd));
}
#else
extern "C" void thd_wait_begin(MYSQL_THD thd, int wait_type)
{
  /* do NOTHING for the embedded library */
  return;
}

extern "C" void thd_wait_end(MYSQL_THD thd)
{
  /* do NOTHING for the embedded library */
  return;
}
#endif
#endif // INNODB_COMPATIBILITY_HOOKS */

/****************************************************************************
  Handling of statement states in functions and triggers.

  This is used to ensure that the function/trigger gets a clean state
  to work with and does not cause any side effects of the calling statement.

  It also allows most stored functions and triggers to replicate even
  if they are used items that would normally be stored in the binary
  replication (like last_insert_id() etc...)

  The following things is done
  - Disable binary logging for the duration of the statement
  - Disable multi-result-sets for the duration of the statement
  - Value of last_insert_id() is saved and restored
  - Value set by 'SET INSERT_ID=#' is reset and restored
  - Value for found_rows() is reset and restored
  - examined_row_count is added to the total
  - cuted_fields is added to the total
  - new savepoint level is created and destroyed

  NOTES:
    Seed for random() is saved for the first! usage of RAND()
    We reset examined_row_count and cuted_fields and add these to the
    result to ensure that if we have a bug that would reset these within
    a function, we are not loosing any rows from the main statement.

    We do not reset value of last_insert_id().
****************************************************************************/

void THD::reset_sub_statement_state(Sub_statement_state *backup,
                                    uint new_state)
{
#ifndef EMBEDDED_LIBRARY
  /* BUG#33029, if we are replicating from a buggy master, reset
     auto_inc_intervals_forced to prevent substatement
     (triggers/functions) from using erroneous INSERT_ID value
   */
  if (rpl_master_erroneous_autoinc(this))
  {
    DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
    auto_inc_intervals_forced.swap(&backup->auto_inc_intervals_forced);
  }
#endif
  
  backup->option_bits=     variables.option_bits;
  backup->count_cuted_fields= count_cuted_fields;
  backup->in_sub_stmt=     in_sub_stmt;
  backup->enable_slow_log= enable_slow_log;
  backup->limit_found_rows= limit_found_rows;
  backup->examined_row_count= m_examined_row_count;
  backup->sent_row_count= m_sent_row_count;
  backup->cuted_fields=     cuted_fields;
  backup->client_capabilities= client_capabilities;
  backup->savepoints= transaction.savepoints;
  backup->first_successful_insert_id_in_prev_stmt= 
    first_successful_insert_id_in_prev_stmt;
  backup->first_successful_insert_id_in_cur_stmt= 
    first_successful_insert_id_in_cur_stmt;

  if ((!lex->requires_prelocking() || is_update_query(lex->sql_command)) &&
      !is_current_stmt_binlog_format_row())
  {
    variables.option_bits&= ~OPTION_BIN_LOG;
  }

  if ((backup->option_bits & OPTION_BIN_LOG) &&
       is_update_query(lex->sql_command) &&
       !is_current_stmt_binlog_format_row())
    mysql_bin_log.start_union_events(this, this->query_id);

  /* Disable result sets */
  client_capabilities &= ~CLIENT_MULTI_RESULTS;
  in_sub_stmt|= new_state;
  m_examined_row_count= 0;
  m_sent_row_count= 0;
  cuted_fields= 0;
  transaction.savepoints= 0;
  first_successful_insert_id_in_cur_stmt= 0;
}


void THD::restore_sub_statement_state(Sub_statement_state *backup)
{
  DBUG_ENTER("THD::restore_sub_statement_state");
#ifndef EMBEDDED_LIBRARY
  /* BUG#33029, if we are replicating from a buggy master, restore
     auto_inc_intervals_forced so that the top statement can use the
     INSERT_ID value set before this statement.
   */
  if (rpl_master_erroneous_autoinc(this))
  {
    backup->auto_inc_intervals_forced.swap(&auto_inc_intervals_forced);
    DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
  }
#endif

  /*
    To save resources we want to release savepoints which were created
    during execution of function or trigger before leaving their savepoint
    level. It is enough to release first savepoint set on this level since
    all later savepoints will be released automatically.
  */
  if (transaction.savepoints)
  {
    SAVEPOINT *sv;
    for (sv= transaction.savepoints; sv->prev; sv= sv->prev)
    {}
    /* ha_release_savepoint() never returns error. */
    (void)ha_release_savepoint(this, sv);
  }
  count_cuted_fields= backup->count_cuted_fields;
  transaction.savepoints= backup->savepoints;
  variables.option_bits= backup->option_bits;
  in_sub_stmt=      backup->in_sub_stmt;
  enable_slow_log=  backup->enable_slow_log;
  first_successful_insert_id_in_prev_stmt= 
    backup->first_successful_insert_id_in_prev_stmt;
  first_successful_insert_id_in_cur_stmt= 
    backup->first_successful_insert_id_in_cur_stmt;
  limit_found_rows= backup->limit_found_rows;
  set_sent_row_count(backup->sent_row_count);
  client_capabilities= backup->client_capabilities;
  /*
    If we've left sub-statement mode, reset the fatal error flag.
    Otherwise keep the current value, to propagate it up the sub-statement
    stack.
  */
  if (!in_sub_stmt)
    is_fatal_sub_stmt_error= FALSE;

  if ((variables.option_bits & OPTION_BIN_LOG) && is_update_query(lex->sql_command) &&
       !is_current_stmt_binlog_format_row())
    mysql_bin_log.stop_union_events(this);

  /*
    The following is added to the old values as we are interested in the
    total complexity of the query
  */
  inc_examined_row_count(backup->examined_row_count);
  cuted_fields+=       backup->cuted_fields;
  DBUG_VOID_RETURN;
}


void THD::set_statement(Statement *stmt)
{
  mysql_mutex_lock(&LOCK_thd_data);
  Statement::set_statement(stmt);
  mysql_mutex_unlock(&LOCK_thd_data);
}

void THD::set_sent_row_count(ha_rows count)
{
  m_sent_row_count= count;
  MYSQL_SET_STATEMENT_ROWS_SENT(m_statement_psi, m_sent_row_count);
}

void THD::set_examined_row_count(ha_rows count)
{
  m_examined_row_count= count;
  MYSQL_SET_STATEMENT_ROWS_EXAMINED(m_statement_psi, m_examined_row_count);
}

void THD::inc_sent_row_count(ha_rows count)
{
  m_sent_row_count+= count;
  MYSQL_SET_STATEMENT_ROWS_SENT(m_statement_psi, m_sent_row_count);
}

void THD::inc_examined_row_count(ha_rows count)
{
  m_examined_row_count+= count;
  MYSQL_SET_STATEMENT_ROWS_EXAMINED(m_statement_psi, m_examined_row_count);
}

void THD::inc_status_created_tmp_disk_tables()
{
  status_var_increment(status_var.created_tmp_disk_tables);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_created_tmp_disk_tables)(m_statement_psi, 1);
#endif
}

void THD::inc_status_created_tmp_tables()
{
  status_var_increment(status_var.created_tmp_tables);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_created_tmp_tables)(m_statement_psi, 1);
#endif
}

void THD::inc_status_select_full_join()
{
  status_var_increment(status_var.select_full_join_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_select_full_join)(m_statement_psi, 1);
#endif
}

void THD::inc_status_select_full_range_join()
{
  status_var_increment(status_var.select_full_range_join_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_select_full_range_join)(m_statement_psi, 1);
#endif
}

void THD::inc_status_select_range()
{
  status_var_increment(status_var.select_range_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_select_range)(m_statement_psi, 1);
#endif
}

void THD::inc_status_select_range_check()
{
  status_var_increment(status_var.select_range_check_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_select_range_check)(m_statement_psi, 1);
#endif
}

void THD::inc_status_select_scan()
{
  status_var_increment(status_var.select_scan_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_select_scan)(m_statement_psi, 1);
#endif
}

void THD::inc_status_sort_merge_passes()
{
  status_var_increment(status_var.filesort_merge_passes);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_sort_merge_passes)(m_statement_psi, 1);
#endif
}

void THD::inc_status_sort_range()
{
  status_var_increment(status_var.filesort_range_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_sort_range)(m_statement_psi, 1);
#endif
}

void THD::inc_status_sort_rows(ha_rows count)
{
  statistic_add(status_var.filesort_rows, count, &LOCK_status);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_sort_rows)(m_statement_psi, count);
#endif
}

void THD::inc_status_sort_scan()
{
  status_var_increment(status_var.filesort_scan_count);
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(inc_statement_sort_scan)(m_statement_psi, 1);
#endif
}

void THD::set_status_no_index_used()
{
  server_status|= SERVER_QUERY_NO_INDEX_USED;
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(set_statement_no_index_used)(m_statement_psi);
#endif
}

void THD::set_status_no_good_index_used()
{
  server_status|= SERVER_QUERY_NO_GOOD_INDEX_USED;
#ifdef HAVE_PSI_STATEMENT_INTERFACE
  PSI_STATEMENT_CALL(set_statement_no_good_index_used)(m_statement_psi);
#endif
}

void THD::set_command(enum enum_server_command command)
{
  m_command= command;
#ifdef HAVE_PSI_THREAD_INTERFACE
  PSI_STATEMENT_CALL(set_thread_command)(m_command);
#endif
}


void THD::set_query(const CSET_STRING &string_arg)
{
  mysql_mutex_lock(&LOCK_thd_data);
  set_query_inner(string_arg);
  mysql_mutex_unlock(&LOCK_thd_data);

#ifdef HAVE_PSI_THREAD_INTERFACE
  PSI_THREAD_CALL(set_thread_info)(query(), query_length());
#endif
}

void THD::set_query_and_id(char *query_arg, uint32 query_length_arg,
                           const CHARSET_INFO *cs,
                           query_id_t new_query_id)
{
  mysql_mutex_lock(&LOCK_thd_data);
  set_query_inner(query_arg, query_length_arg, cs);
  query_id= new_query_id;
  mysql_mutex_unlock(&LOCK_thd_data);
}

void THD::set_query_id(query_id_t new_query_id)
{
  mysql_mutex_lock(&LOCK_thd_data);
  query_id= new_query_id;
  mysql_mutex_unlock(&LOCK_thd_data);
}

void THD::set_mysys_var(struct st_my_thread_var *new_mysys_var)
{
  mysql_mutex_lock(&LOCK_thd_data);
  mysys_var= new_mysys_var;
  mysql_mutex_unlock(&LOCK_thd_data);
}

void THD::leave_locked_tables_mode()
{
  if (locked_tables_mode == LTM_LOCK_TABLES)
  {
    /*
      When leaving LOCK TABLES mode we have to change the duration of most
      of the metadata locks being held, except for HANDLER and GRL locks,
      to transactional for them to be properly released at UNLOCK TABLES.
    */
    mdl_context.set_transaction_duration_for_all_locks();
    /*
      Make sure we don't release the global read lock and commit blocker
      when leaving LTM.
    */
    global_read_lock.set_explicit_lock_duration(this);
    /* Also ensure that we don't release metadata locks for open HANDLERs. */
    if (handler_tables_hash.records)
      mysql_ha_set_explicit_lock_duration(this);
  }
  locked_tables_mode= LTM_NONE;
}

void THD::get_definer(LEX_USER *definer)
{
  binlog_invoker();
#if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
  if (slave_thread && has_invoker())
  {
    definer->user = invoker_user;
    definer->host= invoker_host;
    definer->password.str= NULL;
    definer->password.length= 0;
    definer->plugin.str= (char *) "";
    definer->plugin.length= 0;
    definer->auth.str=  (char *) "";
    definer->auth.length= 0;
  }
  else
#endif
    get_default_definer(this, definer);
}


void mark_transaction_to_rollback(THD *thd, bool all)
{
  if (thd)
  {
    thd->is_fatal_sub_stmt_error= TRUE;
    thd->transaction_rollback_request= all;
    /*
      Aborted transactions can not be IGNOREd.
      Switch off the IGNORE flag for the current
      SELECT_LEX. This should allow my_error()
      to report the error and abort the execution
      flow, even in presence
      of IGNORE clause.
    */
    if (thd->lex->current_select)
      thd->lex->current_select->no_error= FALSE;
  }
}
/***************************************************************************
  Handling of XA id cacheing
***************************************************************************/

mysql_mutex_t LOCK_xid_cache;
HASH xid_cache;

extern "C" uchar *xid_get_hash_key(const uchar *, size_t *, my_bool);
extern "C" void xid_free_hash(void *);

uchar *xid_get_hash_key(const uchar *ptr, size_t *length,
                                  my_bool not_used __attribute__((unused)))
{
  *length=((XID_STATE*)ptr)->xid.key_length();
  return ((XID_STATE*)ptr)->xid.key();
}

void xid_free_hash(void *ptr)
{
  if (!((XID_STATE*)ptr)->in_thd)
    my_free(ptr);
}

#ifdef HAVE_PSI_INTERFACE
static PSI_mutex_key key_LOCK_xid_cache;

static PSI_mutex_info all_xid_mutexes[]=
{
  { &key_LOCK_xid_cache, "LOCK_xid_cache", PSI_FLAG_GLOBAL}
};

static void init_xid_psi_keys(void)
{
  const char* category= "sql";
  int count;

  count= array_elements(all_xid_mutexes);
  mysql_mutex_register(category, all_xid_mutexes, count);
}
#endif /* HAVE_PSI_INTERFACE */

bool xid_cache_init()
{
#ifdef HAVE_PSI_INTERFACE
  init_xid_psi_keys();
#endif

  mysql_mutex_init(key_LOCK_xid_cache, &LOCK_xid_cache, MY_MUTEX_INIT_FAST);
  return my_hash_init(&xid_cache, &my_charset_bin, 100, 0, 0,
                      xid_get_hash_key, xid_free_hash, 0) != 0;
}

void xid_cache_free()
{
  if (my_hash_inited(&xid_cache))
  {
    my_hash_free(&xid_cache);
    mysql_mutex_destroy(&LOCK_xid_cache);
  }
}

XID_STATE *xid_cache_search(XID *xid)
{
  mysql_mutex_lock(&LOCK_xid_cache);
  XID_STATE *res=(XID_STATE *)my_hash_search(&xid_cache, xid->key(),
                                             xid->key_length());
  mysql_mutex_unlock(&LOCK_xid_cache);
  return res;
}


bool xid_cache_insert(XID *xid, enum xa_states xa_state)
{
  XID_STATE *xs;
  my_bool res;
  mysql_mutex_lock(&LOCK_xid_cache);
  if (my_hash_search(&xid_cache, xid->key(), xid->key_length()))
    res=0;
  else if (!(xs=(XID_STATE *)my_malloc(sizeof(*xs), MYF(MY_WME))))
    res=1;
  else
  {
    xs->xa_state=xa_state;
    xs->xid.set(xid);
    xs->in_thd=0;
    xs->rm_error=0;
    res=my_hash_insert(&xid_cache, (uchar*)xs);
  }
  mysql_mutex_unlock(&LOCK_xid_cache);
  return res;
}


bool xid_cache_insert(XID_STATE *xid_state)
{
  mysql_mutex_lock(&LOCK_xid_cache);
  if (my_hash_search(&xid_cache, xid_state->xid.key(),
      xid_state->xid.key_length()))
  {
    mysql_mutex_unlock(&LOCK_xid_cache);
    my_error(ER_XAER_DUPID, MYF(0));
    return true;
  }
  bool res= my_hash_insert(&xid_cache, (uchar*)xid_state);
  mysql_mutex_unlock(&LOCK_xid_cache);
  return res;
}


void xid_cache_delete(XID_STATE *xid_state)
{
  mysql_mutex_lock(&LOCK_xid_cache);
  my_hash_delete(&xid_cache, (uchar *)xid_state);
  mysql_mutex_unlock(&LOCK_xid_cache);
}


void THD::set_next_event_pos(const char* _filename, ulonglong _pos)
{
  char*& filename= binlog_next_event_pos.file_name;
  if (filename == NULL)
  {
    /* First time, allocate maximal buffer */
    filename= (char*) my_malloc(FN_REFLEN+1, MYF(MY_WME));
    if (filename == NULL) return;
  }

  assert(strlen(_filename) <= FN_REFLEN);
  strcpy(filename, _filename);
  filename[ FN_REFLEN ]= 0;

  binlog_next_event_pos.pos= _pos;
};

void THD::clear_next_event_pos()
{
  if (binlog_next_event_pos.file_name != NULL)
  {
    my_free(binlog_next_event_pos.file_name);
  }
  binlog_next_event_pos.file_name= NULL;
  binlog_next_event_pos.pos= 0;
};

void THD::set_user_connect(USER_CONN *uc)
{
  DBUG_ENTER("THD::set_user_connect");

  m_user_connect= uc;

  DBUG_VOID_RETURN;
}

void THD::increment_user_connections_counter()
{
  DBUG_ENTER("THD::increment_user_connections_counter");

  m_user_connect->connections++;

  DBUG_VOID_RETURN;
}

void THD::decrement_user_connections_counter()
{
  DBUG_ENTER("THD::decrement_user_connections_counter");

  DBUG_ASSERT(m_user_connect->connections > 0);
  m_user_connect->connections--;

  DBUG_VOID_RETURN;
}

void THD::increment_con_per_hour_counter()
{
  DBUG_ENTER("THD::decrement_conn_per_hour_counter");

  m_user_connect->conn_per_hour++;

  DBUG_VOID_RETURN;
}

void THD::increment_updates_counter()
{
  DBUG_ENTER("THD::increment_updates_counter");

  m_user_connect->updates++;

  DBUG_VOID_RETURN;
}

void THD::increment_questions_counter()
{
  DBUG_ENTER("THD::increment_updates_counter");

  m_user_connect->questions++;

  DBUG_VOID_RETURN;
}

/*
  Reset per-hour user resource limits when it has been more than
  an hour since they were last checked

  SYNOPSIS:
    time_out_user_resource_limits()

  NOTE:
    This assumes that the LOCK_user_conn mutex has been acquired, so it is
    safe to test and modify members of the USER_CONN structure.
*/
void THD::time_out_user_resource_limits()
{
  mysql_mutex_assert_owner(&LOCK_user_conn);
  ulonglong check_time= start_utime;
  DBUG_ENTER("time_out_user_resource_limits");

  /* If more than a hour since last check, reset resource checking */
  if (check_time - m_user_connect->reset_utime >= LL(3600000000))
  {
    m_user_connect->questions=1;
    m_user_connect->updates=0;
    m_user_connect->conn_per_hour=0;
    m_user_connect->reset_utime= check_time;
  }

  DBUG_VOID_RETURN;
}