mariadb/server-tools/instance-manager/instance.cc

/* Copyright (C) 2004 MySQL AB

   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; either version 2 of the License, or
   (at your option) any later version.

   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 */

#ifdef __GNUC__
#pragma implementation
#endif

#include "instance.h"
#include "mysql_manager_error.h"
#include "log.h"
#include "instance_map.h"
#include <my_sys.h>
#include <signal.h>
#include <m_string.h>
#include <sys/wait.h>


C_MODE_START

pthread_handler_decl(proxy, arg)
{
  Instance *instance= (Instance *) arg;
  instance->fork_and_monitor();
  return 0;
}

C_MODE_END


/*
  The method starts an instance.

  SYNOPSYS
    start()

  RETURN
    0                             ok
    ER_CANNOT_START_INSTANCE      Cannot start instance
    ER_INSTANCE_ALREADY_STARTED   The instance on the specified port/socket
                                  is already started
*/

int Instance::start()
{
  pid_t pid;

  /* clear crash flag */
  pthread_mutex_lock(&LOCK_instance);
  crashed= 0;
  pthread_mutex_unlock(&LOCK_instance);


  if (!is_running())
  {
    if ((pid= options.get_pid()) != 0)          /* check the pidfile */
      if (options.unlink_pidfile())             /* remove stalled pidfile */
        log_error("cannot remove pidfile for instance %i, this might be \
                  since IM lacks permmissions or hasn't found the pidifle",
                  options.instance_name);

    /*
      No need to monitor this thread in the Thread_registry, as all
      instances are to be stopped during shutdown.
    */
    pthread_t proxy_thd_id;
    pthread_attr_t proxy_thd_attr;
    int rc;

    pthread_attr_init(&proxy_thd_attr);
    pthread_attr_setdetachstate(&proxy_thd_attr, PTHREAD_CREATE_DETACHED);
    rc= pthread_create(&proxy_thd_id, &proxy_thd_attr, proxy,
                       this);
    pthread_attr_destroy(&proxy_thd_attr);
    if (rc)
    {
      log_error("Instance::start(): pthread_create(proxy) failed");
      return ER_CANNOT_START_INSTANCE;
    }

    return 0;
  }

  /* the instance is started already */
  return ER_INSTANCE_ALREADY_STARTED;
}


void Instance::fork_and_monitor()
{
  pid_t pid;
  log_info("starting instance %s", options.instance_name);
  switch (pid= fork()) {
  case 0:
    execv(options.mysqld_path, options.argv);
    /* exec never returns */
    exit(1);
  case -1:
    log_info("cannot fork() to start instance %s", options.instance_name);
    return;
  default:
    wait(NULL);
    /* set instance state to crashed */
    pthread_mutex_lock(&LOCK_instance);
    crashed= 1;
    pthread_mutex_unlock(&LOCK_instance);

    /*
      Wake connection threads waiting for an instance to stop. This
      is needed if a user issued command to stop an instance via
      mysql connection. This is not the case if Guardian stop the thread.
    */
    pthread_cond_signal(&COND_instance_restarted);
    /* wake guardian */
    pthread_cond_signal(&instance_map->guardian->COND_guardian);
    /* thread exits */
    return;
  }
  /* we should never end up here */
  DBUG_ASSERT(0);
}


Instance::Instance(): crashed(0)
{
  pthread_mutex_init(&LOCK_instance, 0);
  pthread_cond_init(&COND_instance_restarted, 0);
}


Instance::~Instance()
{
  pthread_mutex_destroy(&LOCK_instance);
  pthread_cond_destroy(&COND_instance_restarted);
}


int Instance::is_crashed()
{
  int val;
  pthread_mutex_lock(&LOCK_instance);
  val= crashed;
  pthread_mutex_unlock(&LOCK_instance);
  return val;
}


bool Instance::is_running()
{
  MYSQL mysql;
  uint port= 0;
  const char *socket= NULL;
  const char *password= "321rarepassword213";
  const char *username= "645rareusername945";
  const char *access_denied_message= "Access denied for user";
  bool return_val;

  if (options.mysqld_port)
    port= atoi(strchr(options.mysqld_port, '=') + 1);

  if (options.mysqld_socket)
    socket= strchr(options.mysqld_socket, '=') + 1;

  pthread_mutex_lock(&LOCK_instance);

  mysql_init(&mysql);
  /* try to connect to a server with a fake username/password pair */
  if (mysql_real_connect(&mysql, LOCAL_HOST, username,
                         password,
                         NullS, port,
                         socket, 0))
  {
    /*
      We have successfully connected to the server using fake
      username/password. Write a warning to the logfile.
    */
    log_info("The Instance Manager was able to log into you server \
             with faked compiled-in password while checking server status. \
             Looks like something is wrong.");
    pthread_mutex_unlock(&LOCK_instance);
    return_val= TRUE;                           /* server is alive */
  }
  else
  {
    if (!strncmp(access_denied_message, mysql_error(&mysql),
                 sizeof(access_denied_message)-1))
    {
      return_val= TRUE;
    }
    else
      return_val= FALSE;
  }

  mysql_close(&mysql);
  pthread_mutex_unlock(&LOCK_instance);

  return return_val;
}


/*
  Stop an instance.

  SYNOPSYS
    stop()

  RETURN:
    0                            ok
    ER_INSTANCE_IS_NOT_STARTED   Looks like the instance it is not started
    ER_STOP_INSTANCE             mysql_shutdown reported an error
*/

int Instance::stop()
{
  pid_t pid;
  struct timespec timeout;
  int waitchild= DEFAULT_SHUTDOWN_DELAY;

  if (options.shutdown_delay != NULL)
    waitchild= atoi(options.shutdown_delay);

  kill_instance(SIGTERM);
  /* sleep on condition to wait for SIGCHLD */

  timeout.tv_sec= time(NULL) + waitchild;
  timeout.tv_nsec= 0;
  if (pthread_mutex_lock(&LOCK_instance))
    goto err;

  while (options.get_pid() != 0)              /* while server isn't stopped */
  {
    int status;

    status= pthread_cond_timedwait(&COND_instance_restarted,
                                   &LOCK_instance,
                                   &timeout);
    if (status == ETIMEDOUT)
      break;
  }

  pthread_mutex_unlock(&LOCK_instance);

  kill_instance(SIGKILL);

  return 0;

  return ER_INSTANCE_IS_NOT_STARTED;
err:
  return ER_STOP_INSTANCE;
}


void Instance::kill_instance(int signum)
{
  pid_t pid;
  /* if there are no pid, everything seems to be fine */
  if ((pid= options.get_pid()) != 0)            /* get pid from pidfile */
  {
    /*
      If we cannot kill mysqld, then it has propably crashed.
      Let us try to remove staled pidfile and return successfully
      as mysqld is probably stopped.
    */
    if (!kill(pid, signum))
      options.unlink_pidfile();
    else
      if (signum == SIGKILL)      /* really killed instance with SIGKILL */
        log_error("The instance %s is being stopped forsibly. Normally \
                  it should not happed. Probably the instance has been \
                  hanging. You should also check your IM setup",
                  options.instance_name);
  }
  return;
}

/*
  We execute this function to initialize instance parameters.
  Return value: 0 - ok. 1 - unable to init DYNAMIC_ARRAY.
*/

int Instance::init(const char *name_arg)
{
  return options.init(name_arg);
}


int Instance::complete_initialization(Instance_map *instance_map_arg)
{
  instance_map= instance_map_arg;
  return 0;
}