mariadb/sql/repl_failsafe.cc

/* Copyright (C) 2001-2006 MySQL AB & Sasha, 2008-2009 Sun Microsystems, Inc

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/**
  @file

  All of the functions defined in this file which are not used (the ones to
  handle failsafe) are not used; their code has not been updated for more
  than one year now so should be considered as BADLY BROKEN. Do not enable
  it. The used functions (to handle LOAD DATA FROM MASTER, plus some small
  functions like register_slave()) are working.
*/

#include "sql_priv.h"
#include "sql_parse.h"                          // check_access
#ifdef HAVE_REPLICATION

#include "repl_failsafe.h"
#include "sql_acl.h"                            // REPL_SLAVE_ACL
#include "sql_repl.h"
#include "slave.h"
#include "rpl_mi.h"
#include "rpl_filter.h"
#include "log_event.h"
#include "sql_db.h"                             // mysql_create_db
#include <mysql.h>

#define SLAVE_LIST_CHUNK 128
#define SLAVE_ERRMSG_SIZE (FN_REFLEN+64)


ulong rpl_status=RPL_NULL;
mysql_mutex_t LOCK_rpl_status;
mysql_cond_t COND_rpl_status;
HASH slave_list;

const char *rpl_role_type[] = {"MASTER","SLAVE",NullS};
TYPELIB rpl_role_typelib = {array_elements(rpl_role_type)-1,"",
			    rpl_role_type, NULL};

const char* rpl_status_type[]=
{
  "AUTH_MASTER","IDLE_SLAVE","ACTIVE_SLAVE","LOST_SOLDIER","TROOP_SOLDIER",
  "RECOVERY_CAPTAIN","NULL",NullS
};

static Slave_log_event* find_slave_event(IO_CACHE* log,
					 const char* log_file_name,
					 char* errmsg);

/*
  All of the functions defined in this file which are not used (the ones to
  handle failsafe) are not used; their code has not been updated for more than
  one year now so should be considered as BADLY BROKEN. Do not enable it.
  The used functions (to handle LOAD DATA FROM MASTER, plus some small
  functions like register_slave()) are working.
*/

void change_rpl_status(ulong from_status, ulong to_status)
{
  mysql_mutex_lock(&LOCK_rpl_status);
  if (rpl_status == from_status || rpl_status == RPL_ANY)
    rpl_status = to_status;
  mysql_cond_signal(&COND_rpl_status);
  mysql_mutex_unlock(&LOCK_rpl_status);
}


#define get_object(p, obj, msg) \
{\
  uint len = (uint)*p++;  \
  if (p + len > p_end || len >= sizeof(obj)) \
  {\
    errmsg= msg;\
    goto err; \
  }\
  strmake(obj,(char*) p,len); \
  p+= len; \
}\


static inline int cmp_master_pos(Slave_log_event* sev, LEX_MASTER_INFO* mi)
{
  return cmp_master_pos(sev->master_log, sev->master_pos, mi->log_file_name,
			mi->pos);
}


void unregister_slave(THD* thd, bool only_mine, bool need_mutex)
{
  if (thd->server_id)
  {
    if (need_mutex)
      mysql_mutex_lock(&LOCK_slave_list);

    SLAVE_INFO* old_si;
    if ((old_si = (SLAVE_INFO*)my_hash_search(&slave_list,
                                              (uchar*)&thd->server_id, 4)) &&
	(!only_mine || old_si->thd == thd))
    my_hash_delete(&slave_list, (uchar*)old_si);

    if (need_mutex)
      mysql_mutex_unlock(&LOCK_slave_list);
  }
}


/**
  Register slave in 'slave_list' hash table.

  @return
    0	ok
  @return
    1	Error.   Error message sent to client
*/

int register_slave(THD* thd, uchar* packet, uint packet_length)
{
  int res;
  SLAVE_INFO *si;
  uchar *p= packet, *p_end= packet + packet_length;
  const char *errmsg= "Wrong parameters to function register_slave";

  if (check_access(thd, REPL_SLAVE_ACL, any_db, NULL, NULL, 0, 0))
    return 1;
  if (!(si = (SLAVE_INFO*)my_malloc(sizeof(SLAVE_INFO), MYF(MY_WME))))
    goto err2;

  thd->server_id= si->server_id= uint4korr(p);
  p+= 4;
  get_object(p,si->host, "Failed to register slave: too long 'report-host'");
  get_object(p,si->user, "Failed to register slave: too long 'report-user'");
  get_object(p,si->password, "Failed to register slave; too long 'report-password'");
  if (p+10 > p_end)
    goto err;
  si->port= uint2korr(p);
  p += 2;
  /* 
     We need to by pass the bytes used in the fake rpl_recovery_rank
     variable. It was removed in patch for BUG#13963. But this would 
     make a server with that patch unable to connect to an old master.
     See: BUG#49259
  */
  // si->rpl_recovery_rank= uint4korr(p);
  p += 4;
  if (!(si->master_id= uint4korr(p)))
    si->master_id= server_id;
  si->thd= thd;

  mysql_mutex_lock(&LOCK_slave_list);
  unregister_slave(thd,0,0);
  res= my_hash_insert(&slave_list, (uchar*) si);
  mysql_mutex_unlock(&LOCK_slave_list);
  return res;

err:
  my_free(si);
  my_message(ER_UNKNOWN_ERROR, errmsg, MYF(0)); /* purecov: inspected */
err2:
  return 1;
}

extern "C" uint32
*slave_list_key(SLAVE_INFO* si, size_t *len,
		my_bool not_used __attribute__((unused)))
{
  *len = 4;
  return &si->server_id;
}

extern "C" void slave_info_free(void *s)
{
  my_free(s);
}

#ifdef HAVE_PSI_INTERFACE
static PSI_mutex_key key_LOCK_slave_list;

static PSI_mutex_info all_slave_list_mutexes[]=
{
  { &key_LOCK_slave_list, "LOCK_slave_list", PSI_FLAG_GLOBAL}
};

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

  if (PSI_server == NULL)
    return;

  count= array_elements(all_slave_list_mutexes);
  PSI_server->register_mutex(category, all_slave_list_mutexes, count);
}
#endif /* HAVE_PSI_INTERFACE */

void init_slave_list()
{
#ifdef HAVE_PSI_INTERFACE
  init_all_slave_list_mutexes();
#endif

  my_hash_init(&slave_list, system_charset_info, SLAVE_LIST_CHUNK, 0, 0,
               (my_hash_get_key) slave_list_key,
               (my_hash_free_key) slave_info_free, 0);
  mysql_mutex_init(key_LOCK_slave_list, &LOCK_slave_list, MY_MUTEX_INIT_FAST);
}

void end_slave_list()
{
  /* No protection by a mutex needed as we are only called at shutdown */
  if (my_hash_inited(&slave_list))
  {
    my_hash_free(&slave_list);
    mysql_mutex_destroy(&LOCK_slave_list);
  }
}

static int find_target_pos(LEX_MASTER_INFO *mi, IO_CACHE *log, char *errmsg)
{
  my_off_t log_pos =	    (my_off_t) mi->pos;
  uint32 target_server_id = mi->server_id;

  for (;;)
  {
    Log_event* ev;
    if (!(ev= Log_event::read_log_event(log, (mysql_mutex_t*) 0, 0)))
    {
      if (log->error > 0)
	strmov(errmsg, "Binary log truncated in the middle of event");
      else if (log->error < 0)
	strmov(errmsg, "I/O error reading binary log");
      else
	strmov(errmsg, "Could not find target event in the binary log");
      return 1;
    }

    if (ev->log_pos >= log_pos && ev->server_id == target_server_id)
    {
      delete ev;
      mi->pos = my_b_tell(log);
      return 0;
    }
    delete ev;
  }
  /* Impossible */
}

/**
  @details 
  Before 4.0.15 we had a member of THD called log_pos, it was meant for
  failsafe replication code in repl_failsafe.cc which is disabled until
  it is reworked. Event's log_pos used to be preserved through 
  log-slave-updates to make code in repl_failsafe.cc work (this 
  function, SHOW NEW MASTER); but on the other side it caused unexpected
  values in Exec_Master_Log_Pos in A->B->C replication setup, 
  synchronization problems in master_pos_wait(), ... So we 
  (Dmitri & Guilhem) removed it.
  
  So for now this function is broken. 
*/

int translate_master(THD* thd, LEX_MASTER_INFO* mi, char* errmsg)
{
  LOG_INFO linfo;
  char last_log_name[FN_REFLEN];
  IO_CACHE log;
  File file = -1, last_file = -1;
  mysql_mutex_t *log_lock;
  const char* errmsg_p;
  Slave_log_event* sev = 0;
  my_off_t last_pos = 0;
  int error = 1;
  int cmp_res;
  LINT_INIT(cmp_res);
  DBUG_ENTER("translate_master");

  if (!mysql_bin_log.is_open())
  {
    strmov(errmsg,"Binary log is not open");
    DBUG_RETURN(1);
  }

  if (!server_id_supplied)
  {
    strmov(errmsg, "Misconfigured master - server id was not set");
    DBUG_RETURN(1);
  }

  if (mysql_bin_log.find_log_pos(&linfo, NullS, 1))
  {
    strmov(errmsg,"Could not find first log");
    DBUG_RETURN(1);
  }
  thd->current_linfo = &linfo;

  bzero((char*) &log,sizeof(log));
  log_lock = mysql_bin_log.get_log_lock();
  mysql_mutex_lock(log_lock);

  for (;;)
  {
    if ((file=open_binlog(&log, linfo.log_file_name, &errmsg_p)) < 0)
    {
      strmov(errmsg, errmsg_p);
      goto err;
    }

    if (!(sev = find_slave_event(&log, linfo.log_file_name, errmsg)))
      goto err;

    cmp_res = cmp_master_pos(sev, mi);
    delete sev;

    if (!cmp_res)
    {
      /* Copy basename */
      fn_format(mi->log_file_name, linfo.log_file_name, "","",1);
      mi->pos = my_b_tell(&log);
      goto mi_inited;
    }
    else if (cmp_res > 0)
    {
      if (!last_pos)
      {
	strmov(errmsg,
	       "Slave event in first log points past the target position");
	goto err;
      }
      end_io_cache(&log);
      mysql_file_close(file, MYF(MY_WME));
      if (init_io_cache(&log, (file = last_file), IO_SIZE, READ_CACHE, 0, 0,
			MYF(MY_WME)))
      {
	errmsg[0] = 0;
	goto err;
      }
      break;
    }

    strmov(last_log_name, linfo.log_file_name);
    last_pos = my_b_tell(&log);

    switch (mysql_bin_log.find_next_log(&linfo, 1)) {
    case LOG_INFO_EOF:
      if (last_file >= 0)
       mysql_file_close(last_file, MYF(MY_WME));
      last_file = -1;
      goto found_log;
    case 0:
      break;
    default:
      strmov(errmsg, "Error reading log index");
      goto err;
    }

    end_io_cache(&log);
    if (last_file >= 0)
      mysql_file_close(last_file, MYF(MY_WME));
    last_file = file;
  }

found_log:
  my_b_seek(&log, last_pos);
  if (find_target_pos(mi,&log,errmsg))
    goto err;
  fn_format(mi->log_file_name, last_log_name, "","",1);  /* Copy basename */

mi_inited:
  error = 0;
err:
  mysql_mutex_unlock(log_lock);
  end_io_cache(&log);
  mysql_mutex_lock(&LOCK_thread_count);
  thd->current_linfo = 0;
  mysql_mutex_unlock(&LOCK_thread_count);
  if (file >= 0)
    mysql_file_close(file, MYF(MY_WME));
  if (last_file >= 0 && last_file != file)
    mysql_file_close(last_file, MYF(MY_WME));

  DBUG_RETURN(error);
}


/**
  Caller must delete result when done.
*/

static Slave_log_event* find_slave_event(IO_CACHE* log,
					 const char* log_file_name,
					 char* errmsg)
{
  Log_event* ev;
  int i;
  bool slave_event_found = 0;
  LINT_INIT(ev);

  for (i = 0; i < 2; i++)
  {
    if (!(ev= Log_event::read_log_event(log, (mysql_mutex_t*)0, 0)))
    {
      my_snprintf(errmsg, SLAVE_ERRMSG_SIZE,
		  "Error reading event in log '%s'",
		  (char*)log_file_name);
      return 0;
    }
    if (ev->get_type_code() == SLAVE_EVENT)
    {
      slave_event_found = 1;
      break;
    }
    delete ev;
  }
  if (!slave_event_found)
  {
    my_snprintf(errmsg, SLAVE_ERRMSG_SIZE,
		"Could not find slave event in log '%s'",
		(char*)log_file_name);
    return 0;
  }

  return (Slave_log_event*)ev;
}

/**
  This function is broken now. 

  @seealso translate_master()
*/

bool show_new_master(THD* thd)
{
  Protocol *protocol= thd->protocol;
  DBUG_ENTER("show_new_master");
  List<Item> field_list;
  char errmsg[SLAVE_ERRMSG_SIZE];
  LEX_MASTER_INFO* lex_mi= &thd->lex->mi;

  errmsg[0]=0;					// Safety
  if (translate_master(thd, lex_mi, errmsg))
  {
    if (errmsg[0])
      my_error(ER_ERROR_WHEN_EXECUTING_COMMAND, MYF(0),
               "SHOW NEW MASTER", errmsg);
    DBUG_RETURN(TRUE);
  }
  else
  {
    field_list.push_back(new Item_empty_string("Log_name", 20));
    field_list.push_back(new Item_return_int("Log_pos", 10,
					     MYSQL_TYPE_LONGLONG));
    if (protocol->send_result_set_metadata(&field_list,
                              Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
      DBUG_RETURN(TRUE);
    protocol->prepare_for_resend();
    protocol->store(lex_mi->log_file_name, &my_charset_bin);
    protocol->store((ulonglong) lex_mi->pos);
    if (protocol->write())
      DBUG_RETURN(TRUE);
    my_eof(thd);
    DBUG_RETURN(FALSE);
  }
}

/**
  Asks the master for the list of its other connected slaves.

  This is for failsafe replication:
  in order for failsafe replication to work, the servers involved in
  replication must know of each other. We accomplish this by having each
  slave report to the master how to reach it, and on connection, each
  slave receives information about where the other slaves are.

  @param mysql           pre-existing connection to the master
  @param mi              master info

  @note
    mi is used only to give detailed error messages which include the
    hostname/port of the master, the username used by the slave to connect to
    the master.
    If the user used by the slave to connect to the master does not have the
    REPLICATION SLAVE privilege, it will pop in this function because
    SHOW SLAVE HOSTS will fail on the master.

  @retval
    1           error
  @retval
    0           success
*/

int update_slave_list(MYSQL* mysql, Master_info* mi)
{
  MYSQL_RES* res=0;
  MYSQL_ROW row;
  const char* error=0;
  bool have_auth_info;
  int port_ind;
  DBUG_ENTER("update_slave_list");

  if (mysql_real_query(mysql, STRING_WITH_LEN("SHOW SLAVE HOSTS")) ||
      !(res = mysql_store_result(mysql)))
  {
    error= mysql_error(mysql);
    goto err;
  }

  switch (mysql_num_fields(res)) {
  case 5:
    have_auth_info = 0;
    port_ind=2;
    break;
  case 7:
    have_auth_info = 1;
    port_ind=4;
    break;
  default:
    error= "the master returned an invalid number of fields for SHOW SLAVE \
HOSTS";
    goto err;
  }

  mysql_mutex_lock(&LOCK_slave_list);

  while ((row= mysql_fetch_row(res)))
  {
    uint32 log_server_id;
    SLAVE_INFO* si, *old_si;
    log_server_id = atoi(row[0]);
    if ((old_si= (SLAVE_INFO*)my_hash_search(&slave_list,
                                             (uchar*)&log_server_id,4)))
      si = old_si;
    else
    {
      if (!(si = (SLAVE_INFO*)my_malloc(sizeof(SLAVE_INFO), MYF(MY_WME))))
      {
	error= "the slave is out of memory";
        mysql_mutex_unlock(&LOCK_slave_list);
	goto err;
      }
      si->server_id = log_server_id;
      if (my_hash_insert(&slave_list, (uchar*)si))
      {
        error= "the slave is out of memory";
        mysql_mutex_unlock(&LOCK_slave_list);
        goto err;
      }
    }
    strmake(si->host, row[1], sizeof(si->host)-1);
    si->port = atoi(row[port_ind]);
    si->rpl_recovery_rank = atoi(row[port_ind+1]);
    si->master_id = atoi(row[port_ind+2]);
    if (have_auth_info)
    {
      strmake(si->user, row[2], sizeof(si->user)-1);
      strmake(si->password, row[3], sizeof(si->password)-1);
    }
  }
  mysql_mutex_unlock(&LOCK_slave_list);

err:
  if (res)
    mysql_free_result(res);
  if (error)
  {
    sql_print_error("While trying to obtain the list of slaves from the master "
                    "'%s:%d', user '%s' got the following error: '%s'", 
                    mi->host, mi->port, mi->user, error);
    DBUG_RETURN(1);
  }
  DBUG_RETURN(0);
}


/**
  Execute a SHOW SLAVE HOSTS statement.

  @param thd Pointer to THD object for the client thread executing the
  statement.

  @retval FALSE success
  @retval TRUE failure
*/
bool show_slave_hosts(THD* thd)
{
  List<Item> field_list;
  Protocol *protocol= thd->protocol;
  DBUG_ENTER("show_slave_hosts");

  field_list.push_back(new Item_return_int("Server_id", 10,
					   MYSQL_TYPE_LONG));
  field_list.push_back(new Item_empty_string("Host", 20));
  if (opt_show_slave_auth_info)
  {
    field_list.push_back(new Item_empty_string("User",20));
    field_list.push_back(new Item_empty_string("Password",20));
  }
  field_list.push_back(new Item_return_int("Port", 7, MYSQL_TYPE_LONG));
  field_list.push_back(new Item_return_int("Master_id", 10,
					   MYSQL_TYPE_LONG));

  if (protocol->send_result_set_metadata(&field_list,
                            Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
    DBUG_RETURN(TRUE);

  mysql_mutex_lock(&LOCK_slave_list);

  for (uint i = 0; i < slave_list.records; ++i)
  {
    SLAVE_INFO* si = (SLAVE_INFO*) my_hash_element(&slave_list, i);
    protocol->prepare_for_resend();
    protocol->store((uint32) si->server_id);
    protocol->store(si->host, &my_charset_bin);
    if (opt_show_slave_auth_info)
    {
      protocol->store(si->user, &my_charset_bin);
      protocol->store(si->password, &my_charset_bin);
    }
    protocol->store((uint32) si->port);
    protocol->store((uint32) si->master_id);
    if (protocol->write())
    {
      mysql_mutex_unlock(&LOCK_slave_list);
      DBUG_RETURN(TRUE);
    }
  }
  mysql_mutex_unlock(&LOCK_slave_list);
  my_eof(thd);
  DBUG_RETURN(FALSE);
}

#endif /* HAVE_REPLICATION */