path: root/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; 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 */

#if defined(__GNUC__) && defined(USE_PRAGMA_IMPLEMENTATION)
#pragma implementation
#endif

#include "instance.h"

#include <mysql.h>

#include <signal.h>
#ifndef __WIN__
#include <sys/wait.h>
#endif

#include "guardian.h"
#include "manager.h"
#include "log.h"
#include "mysql_manager_error.h"
#include "portability.h"
#include "priv.h"
#include "thread_registry.h"
#include "instance_map.h"

/* {{{ Platform-specific functions. */

#ifndef __WIN__
typedef pid_t My_process_info;
#else
typedef PROCESS_INFORMATION My_process_info;
#endif

/*
  Proxy thread is a simple way to avoid all pitfalls of the threads
  implementation in the OS (e.g. LinuxThreads). With such a thread we
  don't have to process SIGCHLD, which is a tricky business if we want
  to do it in a portable way.
*/

class Instance_monitor: public Thread
{
public:
  Instance_monitor(Instance *instance_arg) :instance(instance_arg) {}
protected:
  virtual void run();
  void start_and_monitor_instance(Instance_options *old_instance_options,
                                  Instance_map *instance_map,
                                  Thread_registry *thread_registry);
private:
  Instance *instance;
};

void Instance_monitor::run()
{
  start_and_monitor_instance(&instance->options,
                             Manager::get_instance_map(),
                             Manager::get_thread_registry());
  delete this;
}

/*
  Wait for an instance

  SYNOPSIS
    wait_process()
    pi                   Pointer to the process information structure
                         (platform-dependent).

  RETURN
   0  -  Success
   1  -  Error
*/

#ifndef __WIN__
static int wait_process(My_process_info *pi)
{
  /*
    Here we wait for the child created. This process differs for systems
    running LinuxThreads and POSIX Threads compliant systems. This is because
    according to POSIX we could wait() for a child in any thread of the
    process. While LinuxThreads require that wait() is called by the thread,
    which created the child.
    On the other hand we could not expect mysqld to return the pid, we
    got in from fork(), to wait4() fucntion when running on LinuxThreads.
    This is because MySQL shutdown thread is not the one, which was created
    by our fork() call.
    So basically we have two options: whether the wait() call returns only in
    the creator thread, but we cannot use waitpid() since we have no idea
    which pid we should wait for (in fact it should be the pid of shutdown
    thread, but we don't know this one). Or we could use waitpid(), but
    couldn't use wait(), because it could return in any wait() in the program.
  */

  if (Manager::is_linux_threads())
    wait(NULL);                               /* LinuxThreads were detected */
  else
    waitpid(*pi, NULL, 0);

  return 0;
}
#else
static int wait_process(My_process_info *pi)
{
  /* Wait until child process exits. */
  WaitForSingleObject(pi->hProcess, INFINITE);

  DWORD exitcode;
  ::GetExitCodeProcess(pi->hProcess, &exitcode);

  /* Close process and thread handles. */
  CloseHandle(pi->hProcess);
  CloseHandle(pi->hThread);

  /*
    GetExitCodeProces returns zero on failure. We should revert this value
    to report an error.
  */
  return (!exitcode);
}
#endif

/*
  Launch an instance

  SYNOPSIS
    start_process()
    instance_options     Pointer to the options of the instance to be
                         launched.
    pi                   Pointer to the process information structure
                         (platform-dependent).

  RETURN
   FALSE - Success
   TRUE  - Cannot create an instance
*/

#ifndef __WIN__
static bool start_process(Instance_options *instance_options,
                          My_process_info *pi)
{
#ifndef __QNX__
  *pi= fork();
#else
  /*
     On QNX one cannot use fork() in multithreaded environment and we
     should use spawn() or one of it's siblings instead.
     Here we use spawnv(), which  is a combination of fork() and execv()
     in one call. It returns the pid of newly created process (>0) or -1
  */
  *pi= spawnv(P_NOWAIT, instance_options->mysqld_path, instance_options->argv);
#endif

  switch (*pi) {
  case 0:                                       /* never happens on QNX */
    execv(instance_options->mysqld_path.str, instance_options->argv);
    /* exec never returns */
    exit(1);
  case -1:
    log_error("Instance '%s': can not start mysqld: fork() failed.",
              (const char *) instance_options->instance_name.str);
    return TRUE;
  }

  return FALSE;
}
#else
static bool start_process(Instance_options *instance_options,
                          My_process_info *pi)
{
  STARTUPINFO si;

  ZeroMemory(&si, sizeof(STARTUPINFO));
  si.cb= sizeof(STARTUPINFO);
  ZeroMemory(pi, sizeof(PROCESS_INFORMATION));

  int cmdlen= 0;
  for (int i= 0; instance_options->argv[i] != 0; i++)
    cmdlen+= strlen(instance_options->argv[i]) + 3;
  cmdlen++;   /* make room for the null */

  char *cmdline= new char[cmdlen];
  if (cmdline == NULL)
    return TRUE;

  cmdline[0]= 0;
  for (int i= 0; instance_options->argv[i] != 0; i++)
  {
    strcat(cmdline, "\"");
    strcat(cmdline, instance_options->argv[i]);
    strcat(cmdline, "\" ");
  }

  /* Start the child process */
  BOOL result=
    CreateProcess(NULL,          /* Put it all in cmdline */
                  cmdline,       /* Command line */
                  NULL,          /* Process handle not inheritable */
                  NULL,          /* Thread handle not inheritable */
                  FALSE,         /* Set handle inheritance to FALSE */
                  0,             /* No creation flags */
                  NULL,          /* Use parent's environment block */
                  NULL,          /* Use parent's starting directory */
                  &si,           /* Pointer to STARTUPINFO structure */
                  pi);           /* Pointer to PROCESS_INFORMATION structure */
  delete cmdline;

  return !result;
}
#endif

#ifdef __WIN__

BOOL SafeTerminateProcess(HANDLE hProcess, UINT uExitCode)
{
  DWORD dwTID, dwCode, dwErr= 0;
  HANDLE hProcessDup= INVALID_HANDLE_VALUE;
  HANDLE hRT= NULL;
  HINSTANCE hKernel= GetModuleHandle("Kernel32");
  BOOL bSuccess= FALSE;

  BOOL bDup= DuplicateHandle(GetCurrentProcess(),
                             hProcess, GetCurrentProcess(), &hProcessDup,
                             PROCESS_ALL_ACCESS, FALSE, 0);

  // Detect the special case where the process is
  // already dead...
  if (GetExitCodeProcess((bDup) ? hProcessDup : hProcess, &dwCode) &&
      (dwCode == STILL_ACTIVE))
  {
    FARPROC pfnExitProc;

    pfnExitProc= GetProcAddress(hKernel, "ExitProcess");

    hRT= CreateRemoteThread((bDup) ? hProcessDup : hProcess, NULL, 0,
                            (LPTHREAD_START_ROUTINE)pfnExitProc,
                            (PVOID)uExitCode, 0, &dwTID);

    if (hRT == NULL)
      dwErr= GetLastError();
  }
  else
    dwErr= ERROR_PROCESS_ABORTED;

  if (hRT)
  {
    // Must wait process to terminate to
    // guarantee that it has exited...
    WaitForSingleObject((bDup) ? hProcessDup : hProcess, INFINITE);

    CloseHandle(hRT);
    bSuccess= TRUE;
  }

  if (bDup)
    CloseHandle(hProcessDup);

  if (!bSuccess)
    SetLastError(dwErr);

  return bSuccess;
}

int kill(pid_t pid, int signum)
{
  HANDLE processhandle= ::OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid);
  if (signum == SIGTERM)
    ::SafeTerminateProcess(processhandle, 0);
  else
    ::TerminateProcess(processhandle, -1);
  return 0;
}
#endif

/* }}} */

/* {{{ Static constants.  */

const LEX_STRING
Instance::DFLT_INSTANCE_NAME= { C_STRING_WITH_LEN("mysqld") };

/* }}} */


/*
  Fork child, exec an instance and monitor it.

  SYNOPSIS
    start_and_monitor_instance()
    old_instance_options   Pointer to the options of the instance to be
                           launched. This info is likely to become obsolete
                           when function returns from wait_process()
    instance_map           Pointer to the instance_map. We use it to protect
                           the instance from deletion, while we are working
                           with it.

  DESCRIPTION
    Fork a child, then exec and monitor it. When the child is dead,
    find appropriate instance (for this purpose we save its name),
    set appropriate flags and wake all threads waiting for instance
    to stop.

  NOTE
    A separate thread for starting/monitoring instance is a simple way
    to avoid all pitfalls of the threads implementation in the OS (e.g.
    LinuxThreads). For one, with such a thread we don't have to process
    SIGCHLD, which is a tricky business if we want to do it in a
    portable way.

  RETURN
    Function returns no value
*/

void
Instance_monitor::
start_and_monitor_instance(Instance_options *old_instance_options,
                           Instance_map *instance_map,
                           Thread_registry *thread_registry)
{
  Instance_name instance_name(&old_instance_options->instance_name);
  Instance *current_instance;
  My_process_info process_info;
  Thread_info thread_info;

  log_info("Instance '%s': Monitor: started.",
           (const char *) instance->get_name()->str);

  if (!old_instance_options->nonguarded)
  {
    /*
      Register thread in Thread_registry to wait for it to stop on shutdown
      only if instance is guarded. If instance is guarded, the thread will not
      finish, because nonguarded instances are not stopped on shutdown.
    */
    thread_registry->register_thread(&thread_info, FALSE);
  }

  /*
    Lock instance map to guarantee that no instances are deleted during
    strmake() and execv() calls.
  */
  instance_map->lock();

  /*
    Save the instance name in the case if Instance object we
    are using is destroyed. (E.g. by "FLUSH INSTANCES")
  */

  log_info("Instance '%s': Monitor: starting mysqld...",
           (const char *) instance->get_name()->str);

  if (start_process(old_instance_options, &process_info))
  {
    instance_map->unlock();
    return;                                     /* error is logged */
  }

  /* allow users to delete instances */
  instance_map->unlock();

  log_info("Instance '%s': Monitor: waiting for mysqld to stop...",
           (const char *) instance->get_name()->str);

  wait_process(&process_info); /* Don't check for return value. */

  instance_map->lock();

  current_instance= instance_map->find(instance_name.get_str());

  if (current_instance)
    current_instance->set_crash_flag_n_wake_all();

  instance_map->unlock();

  if (!old_instance_options->nonguarded)
    thread_registry->unregister_thread(&thread_info);

  log_info("Instance '%s': Monitor: finished.",
           (const char *) instance->get_name()->str);
}


bool Instance::is_name_valid(const LEX_STRING *name)
{
  const char *name_suffix= name->str + DFLT_INSTANCE_NAME.length;

  if (strncmp(name->str, Instance::DFLT_INSTANCE_NAME.str,
              Instance::DFLT_INSTANCE_NAME.length) != 0)
    return FALSE;

  return *name_suffix == 0 || my_isdigit(default_charset_info, *name_suffix);
}


bool Instance::is_mysqld_compatible_name(const LEX_STRING *name)
{
  return strcmp(name->str, DFLT_INSTANCE_NAME.str) == 0;
}



/* {{{ Constructor & destructor */

Instance::Instance()
  :crashed(FALSE),
  configured(FALSE)
{
  pthread_mutex_init(&LOCK_instance, 0);
  pthread_cond_init(&COND_instance_stopped, 0);
}


Instance::~Instance()
{
  log_info("Instance '%s': destroying...", (const char *) get_name()->str);

  pthread_cond_destroy(&COND_instance_stopped);
  pthread_mutex_destroy(&LOCK_instance);
}

/* }}} */

/*
  Initialize instance options.

  SYNOPSIS
    init()
    name_arg      name of the instance

  RETURN:
    FALSE - ok
    TRUE  - error
*/

bool Instance::init(const LEX_STRING *name_arg)
{
  mysqld_compatible= is_mysqld_compatible_name(name_arg);

  return options.init(name_arg);
}


/*
  Complete instance options initialization.

  SYNOPSIS
    complete_initialization()

  RETURN
    FALSE - ok
    TRUE  - error
*/

bool Instance::complete_initialization()
{
  configured= ! options.complete_initialization();
  return FALSE;
  /*
    TODO: return actual status (from
    Instance_options::complete_initialization()) here.
  */
}

/*
  Determine if mysqld is accepting connections.

  SYNOPSIS
    is_mysqld_running()

  DESCRIPTION
    Try to connect to mysqld with fake login/password to check whether it is
    accepting connections or not.

    MT-NOTE: this operation must be called under acquired LOCK_instance.

  RETURN
    TRUE  - mysqld is alive and accept connections
    FALSE - otherwise.
*/

bool Instance::is_mysqld_running()
{
  MYSQL mysql;
  uint port= options.get_mysqld_port(); /* 0 if not specified. */
  const char *socket= NULL;
  static const char *password= "check_connection";
  static const char *username= "MySQL_Instance_Manager";
  static const char *access_denied_message= "Access denied for user";
  bool return_val;

  if (options.mysqld_socket)
    socket= options.mysqld_socket;

  /* no port was specified => instance falled back to default value */
  if (!port && !options.mysqld_socket)
    port= SERVER_DEFAULT_PORT;

  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_error("Instance '%s': was able to log into mysqld.",
              (const char *) get_name()->str);
    pthread_mutex_unlock(&LOCK_instance);
    return_val= TRUE;                           /* server is alive */
  }
  else
    return_val= test(!strncmp(access_denied_message, mysql_error(&mysql),
                              sizeof(access_denied_message) - 1));

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

  return return_val;
}

/*
  The method starts an instance.

  SYNOPSIS
    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()
{
  /* clear crash flag */
  pthread_mutex_lock(&LOCK_instance);
  crashed= FALSE;
  pthread_mutex_unlock(&LOCK_instance);


  if (configured && !is_mysqld_running())
  {
    Instance_monitor *instance_monitor;
    remove_pid();

    instance_monitor= new Instance_monitor(this);

    if (instance_monitor == NULL || instance_monitor->start(Thread::DETACHED))
    {
      delete instance_monitor;
      log_error("Instance::start(): failed to create the monitoring thread"
                " to start an instance");
      return ER_CANNOT_START_INSTANCE;
    }
    /* The monitoring thread will delete itself when it's finished. */

    return 0;
  }

  /* The instance is started already or misconfigured. */
  return configured ? ER_INSTANCE_ALREADY_STARTED : ER_INSTANCE_MISCONFIGURED;
}

/*
  The method sets the crash flag and wakes all waiters on
  COND_instance_stopped and COND_guardian

  SYNOPSIS
    set_crash_flag_n_wake_all()

  DESCRIPTION
    The method is called when an instance is crashed or terminated.
    In the former case it might indicate that guardian probably should
    restart it.

  RETURN
    Function returns no value
*/

void Instance::set_crash_flag_n_wake_all()
{
  /* set instance state to crashed */
  pthread_mutex_lock(&LOCK_instance);
  crashed= TRUE;
  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_stopped);
  /* wake guardian */
  pthread_cond_signal(&Manager::get_guardian()->COND_guardian);
}


/*
  Stop an instance.

  SYNOPSIS
    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()
{
  struct timespec timeout;
  uint waitchild= (uint)  DEFAULT_SHUTDOWN_DELAY;

  if (is_mysqld_running())
  {
    waitchild= options.get_shutdown_delay();

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

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

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

      status= pthread_cond_timedwait(&COND_instance_stopped,
                                     &LOCK_instance,
                                     &timeout);
      if (status == ETIMEDOUT || status == ETIME)
        break;
    }

    pthread_mutex_unlock(&LOCK_instance);

    kill_mysqld(SIGKILL);

    return 0;
  }

  return ER_INSTANCE_IS_NOT_STARTED;
}


/*
  Send signal to mysqld.

  SYNOPSIS
    kill_mysqld()
*/

void Instance::kill_mysqld(int signum)
{
  pid_t mysqld_pid= options.load_pid();

  if (mysqld_pid == 0)
  {
    log_info("Instance '%s': no pid file to send a signal (%d).",
             (const char *) get_name()->str,
             (int) signum);
    return;
  }

  log_info("Instance '%s': sending %d to %d...",
           (const char *) get_name()->str,
           (int) signum,
           (int) mysqld_pid);

  if (kill(mysqld_pid, signum))
  {
    log_info("Instance '%s': kill() failed.",
             (const char *) get_name()->str);
    return;
  }

  /* Kill suceeded */
  if (signum == SIGKILL)      /* really killed instance with SIGKILL */
  {
    log_error("Instance '%s': killed.",
              (const char *) options.instance_name.str);

    /* After sucessful hard kill the pidfile need to be removed */
    options.unlink_pidfile();
  }
}

/*
  Return crashed flag.

  SYNOPSIS
    is_crashed()

  RETURN
    TRUE  - mysqld crashed
    FALSE - mysqld hasn't crashed yet
*/

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

/*
  Remove pid file.
*/

void Instance::remove_pid()
{
  int mysqld_pid= options.load_pid();

  if (mysqld_pid == 0)
    return;

  if (options.unlink_pidfile())
  {
    log_error("Instance '%s': can not unlink pid file.",
              (const char *) options.instance_name.str);
  }
}