~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 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 */

/*

  Functions to handle initializating and allocationg of all mysys & debug

  thread variables.

*/

#include "mysys_priv.h"

#include <mystrings/m_string.h>

#include <signal.h>

uint thd_lib_detected= 0;

#ifdef USE_TLS

pthread_key(struct st_my_thread_var*, THR_KEY_mysys);

#else

pthread_key(struct st_my_thread_var, THR_KEY_mysys);

#endif /* USE_TLS */

pthread_mutex_t THR_LOCK_malloc,THR_LOCK_open,

	        THR_LOCK_lock,THR_LOCK_isam,THR_LOCK_myisam,THR_LOCK_heap,

                THR_LOCK_net, THR_LOCK_charset, THR_LOCK_threads, THR_LOCK_time;

pthread_cond_t  THR_COND_threads;

uint            THR_thread_count= 0;

uint 		my_thread_end_wait_time= 5;

#if !defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R)

pthread_mutex_t LOCK_localtime_r;

#endif

#ifndef HAVE_GETHOSTBYNAME_R

pthread_mutex_t LOCK_gethostbyname_r;

#endif

#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP

pthread_mutexattr_t my_fast_mutexattr;

#endif

#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP

pthread_mutexattr_t my_errorcheck_mutexattr;

#endif

#ifdef TARGET_OS_LINUX

/*

  Dummy thread spawned in my_thread_global_init() below to avoid

  race conditions in NPTL pthread_exit code.

*/

static pthread_handler_t

nptl_pthread_exit_hack_handler(void *arg __attribute((unused)))

{

  /* Do nothing! */

  pthread_exit(0);

  return 0;

}

#endif /* TARGET_OS_LINUX */

static uint get_thread_lib(void);

/*

  initialize thread environment

  SYNOPSIS

    my_thread_global_init()

  RETURN

    0  ok

    1  error (Couldn't create THR_KEY_mysys)

*/

bool my_thread_global_init(void)

{

  int pth_ret;

  thd_lib_detected= get_thread_lib();

  if ((pth_ret= pthread_key_create(&THR_KEY_mysys, NULL)) != 0)

  {

    fprintf(stderr,"Can't initialize threads: error %d\n", pth_ret);

    return 1;

  }

#ifdef TARGET_OS_LINUX

  /*

    BUG#24507: Race conditions inside current NPTL pthread_exit()

    implementation.

    To avoid a possible segmentation fault during concurrent

    executions of pthread_exit(), a dummy thread is spawned which

    initializes internal variables of pthread lib. See bug description

    for a full explanation.

    TODO: Remove this code when fixed versions of glibc6 are in common

    use.

  */

  if (thd_lib_detected == THD_LIB_NPTL)

  {

    pthread_t       dummy_thread;

    pthread_attr_t  dummy_thread_attr;

    pthread_attr_init(&dummy_thread_attr);

    pthread_attr_setdetachstate(&dummy_thread_attr, PTHREAD_CREATE_DETACHED);

    pthread_create(&dummy_thread,&dummy_thread_attr,

                   nptl_pthread_exit_hack_handler, NULL);

  }

#endif /* TARGET_OS_LINUX */

#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP

  /*

    Set mutex type to "fast" a.k.a "adaptive"

    In this case the thread may steal the mutex from some other thread

    that is waiting for the same mutex.  This will save us some

    context switches but may cause a thread to 'starve forever' while

    waiting for the mutex (not likely if the code within the mutex is

    short).

  */

  pthread_mutexattr_init(&my_fast_mutexattr);

  pthread_mutexattr_settype(&my_fast_mutexattr,

                            PTHREAD_MUTEX_ADAPTIVE_NP);

#endif

#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP

  /*

    Set mutex type to "errorcheck"

  */

  pthread_mutexattr_init(&my_errorcheck_mutexattr);

  pthread_mutexattr_settype(&my_errorcheck_mutexattr,

                            PTHREAD_MUTEX_ERRORCHECK);

#endif

  pthread_mutex_init(&THR_LOCK_malloc,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_open,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_lock,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_isam,MY_MUTEX_INIT_SLOW);

  pthread_mutex_init(&THR_LOCK_myisam,MY_MUTEX_INIT_SLOW);

  pthread_mutex_init(&THR_LOCK_heap,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_net,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_charset,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_threads,MY_MUTEX_INIT_FAST);

  pthread_mutex_init(&THR_LOCK_time,MY_MUTEX_INIT_FAST);

  pthread_cond_init(&THR_COND_threads, NULL);

#if !defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R)

  pthread_mutex_init(&LOCK_localtime_r,MY_MUTEX_INIT_SLOW);

#endif

#ifndef HAVE_GETHOSTBYNAME_R

  pthread_mutex_init(&LOCK_gethostbyname_r,MY_MUTEX_INIT_SLOW);

#endif

  if (my_thread_init())

  {

    my_thread_global_end();			/* Clean up */

    return 1;

  }

  return 0;

}

void my_thread_global_end(void)

{

  struct timespec abstime;

  bool all_threads_killed= 1;

  set_timespec(abstime, my_thread_end_wait_time);

  pthread_mutex_lock(&THR_LOCK_threads);

  while (THR_thread_count > 0)

  {

    int error= pthread_cond_timedwait(&THR_COND_threads, &THR_LOCK_threads,

                                      &abstime);

    if (error == ETIMEDOUT || error == ETIME)

    {

#ifdef HAVE_PTHREAD_KILL

      /*

        We shouldn't give an error here, because if we don't have

        pthread_kill(), programs like mysqld can't ensure that all threads

        are killed when we enter here.

      */

      if (THR_thread_count)

        fprintf(stderr,

                "Error in my_thread_global_end(): %d threads didn't exit\n",

                THR_thread_count);

#endif

      all_threads_killed= 0;

      break;

    }

  }

  pthread_mutex_unlock(&THR_LOCK_threads);

  pthread_key_delete(THR_KEY_mysys);

#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP

  pthread_mutexattr_destroy(&my_fast_mutexattr);

#endif

#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP

  pthread_mutexattr_destroy(&my_errorcheck_mutexattr);

#endif

  pthread_mutex_destroy(&THR_LOCK_malloc);

  pthread_mutex_destroy(&THR_LOCK_open);

  pthread_mutex_destroy(&THR_LOCK_lock);

  pthread_mutex_destroy(&THR_LOCK_isam);

  pthread_mutex_destroy(&THR_LOCK_myisam);

  pthread_mutex_destroy(&THR_LOCK_heap);

  pthread_mutex_destroy(&THR_LOCK_net);

  pthread_mutex_destroy(&THR_LOCK_time);

  pthread_mutex_destroy(&THR_LOCK_charset);

  if (all_threads_killed)

  {

    pthread_mutex_destroy(&THR_LOCK_threads);

    pthread_cond_destroy(&THR_COND_threads);

  }

#if !defined(HAVE_LOCALTIME_R) || !defined(HAVE_GMTIME_R)

  pthread_mutex_destroy(&LOCK_localtime_r);

#endif

#ifndef HAVE_GETHOSTBYNAME_R

  pthread_mutex_destroy(&LOCK_gethostbyname_r);

#endif

}

static my_thread_id thread_id= 0;

/*

  Allocate thread specific memory for the thread, used by mysys

  SYNOPSIS

    my_thread_init()

  NOTES

    We can't use mutex_locks here if we are using windows as

    we may have compiled the program with SAFE_MUTEX, in which

    case the checking of mutex_locks will not work until

    the pthread_self thread specific variable is initialized.

  RETURN

    0  ok

    1  Fatal error; mysys/dbug functions can't be used

*/

bool my_thread_init(void)

{

  struct st_my_thread_var *tmp;

  bool error=0;

#ifdef EXTRA_DEBUG_THREADS

  fprintf(stderr,"my_thread_init(): thread_id: 0x%lx\n",

          (ulong) pthread_self());

#endif  

  if (pthread_getspecific(THR_KEY_mysys))

  {

#ifdef EXTRA_DEBUG_THREADS

    fprintf(stderr,"my_thread_init() called more than once in thread 0x%lx\n",

            (long) pthread_self());

#endif    

    goto end;

  }

  if (!(tmp= (struct st_my_thread_var *) calloc(1, sizeof(*tmp))))

  {

    error= 1;

    goto end;

  }

  pthread_setspecific(THR_KEY_mysys,tmp);

  tmp->pthread_self= pthread_self();

  pthread_mutex_init(&tmp->mutex,MY_MUTEX_INIT_FAST);

  pthread_cond_init(&tmp->suspend, NULL);

  tmp->init= 1;

  pthread_mutex_lock(&THR_LOCK_threads);

  tmp->id= ++thread_id;

  ++THR_thread_count;

  pthread_mutex_unlock(&THR_LOCK_threads);

end:

  return error;

}

/*

  Deallocate memory used by the thread for book-keeping

  SYNOPSIS

    my_thread_end()

  NOTE

    This may be called multiple times for a thread.

    This happens for example when one calls 'mysql_server_init()'

    mysql_server_end() and then ends with a mysql_end().

*/

void my_thread_end(void)

{

  struct st_my_thread_var *tmp;

  tmp= (struct st_my_thread_var *)pthread_getspecific(THR_KEY_mysys);

#ifdef EXTRA_DEBUG_THREADS

  fprintf(stderr,"my_thread_end(): tmp: 0x%lx  pthread_self: 0x%lx  thread_id: %ld\n",

	  (long) tmp, (long) pthread_self(), tmp ? (long) tmp->id : 0L);

#endif  

  if (tmp && tmp->init)

  {

#if !defined(__bsdi__) && !defined(__OpenBSD__)

 /* bsdi and openbsd 3.5 dumps core here */

    pthread_cond_destroy(&tmp->suspend);

#endif

    pthread_mutex_destroy(&tmp->mutex);

#if defined(USE_TLS)

    free(tmp);

#else

    tmp->init= 0;

#endif

    /*

      Decrement counter for number of running threads. We are using this

      in my_thread_global_end() to wait until all threads have called

      my_thread_end and thus freed all memory they have allocated in

      my_thread_init() 

    */

    pthread_mutex_lock(&THR_LOCK_threads);

    assert(THR_thread_count != 0);

    if (--THR_thread_count == 0)

      pthread_cond_signal(&THR_COND_threads);

   pthread_mutex_unlock(&THR_LOCK_threads);

  }

  /* The following free has to be done, even if my_thread_var() is 0 */

#if defined(USE_TLS)

  pthread_setspecific(THR_KEY_mysys,0);

#endif

}

struct st_my_thread_var *_my_thread_var(void)

{

  struct st_my_thread_var *tmp= (struct st_my_thread_var*)pthread_getspecific(THR_KEY_mysys);

#if defined(USE_TLS)

  /* This can only happen in a .DLL */

  if (!tmp)

  {

    my_thread_init();

    tmp=my_pthread_getspecific(struct st_my_thread_var*,THR_KEY_mysys);

  }

#endif

  return tmp;

}

/****************************************************************************

  Get name of current thread.

****************************************************************************/

my_thread_id my_thread_dbug_id()

{

  return my_thread_var->id;

}

static uint get_thread_lib(void)

{

#ifdef _CS_GNU_LIBPTHREAD_VERSION

  char buff[64];

  confstr(_CS_GNU_LIBPTHREAD_VERSION, buff, sizeof(buff));

  if (!strncasecmp(buff, "NPTL", 4))

    return THD_LIB_NPTL;

  if (!strncasecmp(buff, "linuxthreads", 12))

    return THD_LIB_LT;

#endif

  return THD_LIB_OTHER;

}