~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2003 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 */

/* This makes a wrapper for mutex handling to make it easier to debug mutex */

#include "mysys_priv.h"

#if defined(TARGET_OS_LINUX) && !defined (__USE_UNIX98)

#define __USE_UNIX98			/* To get rw locks under Linux */

#endif

#if defined(SAFE_MUTEX)

#undef SAFE_MUTEX			/* Avoid safe_mutex redefinitions */

#include <mysys/my_static.h>

#include <mystrings/m_string.h>

#ifndef DO_NOT_REMOVE_THREAD_WRAPPERS

/* Remove wrappers */

#undef pthread_mutex_t

#undef pthread_mutex_init

#undef pthread_mutex_lock

#undef pthread_mutex_unlock

#undef pthread_mutex_destroy

#undef pthread_cond_wait

#undef pthread_cond_timedwait

#ifdef HAVE_NONPOSIX_PTHREAD_MUTEX_INIT

#define pthread_mutex_init(a,b) my_pthread_mutex_init((a),(b))

#endif

#endif /* DO_NOT_REMOVE_THREAD_WRAPPERS */

static pthread_mutex_t THR_LOCK_mutex;

static uint32_t safe_mutex_count= 0;		/* Number of mutexes created */

#ifdef SAFE_MUTEX_DETECT_DESTROY

static struct st_safe_mutex_info_t *safe_mutex_root= NULL;

#endif

void safe_mutex_global_init(void)

{

  pthread_mutex_init(&THR_LOCK_mutex,MY_MUTEX_INIT_FAST);

}

int safe_mutex_init(safe_mutex_t *mp,

		    const pthread_mutexattr_t *, const char *file, uint32_t line)

{

  memset(mp, 0, sizeof(*mp));

  pthread_mutex_init(&mp->global,MY_MUTEX_INIT_ERRCHK);

  pthread_mutex_init(&mp->mutex,attr);

  /* Mark that mutex is initialized */

  mp->file= file;

  mp->line= line;

#ifdef SAFE_MUTEX_DETECT_DESTROY

  /*

    Monitor the freeing of mutexes.  This code depends on single thread init

    and destroy

  */

  if ((mp->info= (safe_mutex_info_t *) malloc(sizeof(safe_mutex_info_t))))

  {

    struct st_safe_mutex_info_t *info =mp->info;

    info->init_file= file;

    info->init_line= line;

    info->prev= NULL;

    info->next= NULL;

    pthread_mutex_lock(&THR_LOCK_mutex);

    if ((info->next= safe_mutex_root))

      safe_mutex_root->prev= info;

    safe_mutex_root= info;

    safe_mutex_count++;

    pthread_mutex_unlock(&THR_LOCK_mutex);

  }

#else

  thread_safe_increment(safe_mutex_count, &THR_LOCK_mutex);

#endif /* SAFE_MUTEX_DETECT_DESTROY */

  return 0;

}

int safe_mutex_lock(safe_mutex_t *mp, bool try_lock, const char *file, uint32_t line)

{

  int error;

  if (!mp->file)

  {

    fprintf(stderr,

	    "safe_mutex: Trying to lock unitialized mutex at %s, line %d\n",

	    file, line);

    fflush(stderr);

    abort();

  }

  pthread_mutex_lock(&mp->global);

  if (mp->count > 0)

  {

    if (try_lock)

    {

      pthread_mutex_unlock(&mp->global);

      return EBUSY;

    }

    else if (pthread_equal(pthread_self(),mp->thread))

    {

      fprintf(stderr,

              "safe_mutex: Trying to lock mutex at %s, line %d, when the"

              " mutex was already locked at %s, line %d in thread %s\n",

              file,line,mp->file, mp->line, my_thread_name());

      fflush(stderr);

      abort();

    }

  }

  pthread_mutex_unlock(&mp->global);

  /*

    If we are imitating trylock(), we need to take special

    precautions.

    - We cannot use pthread_mutex_lock() only since another thread can

      overtake this thread and take the lock before this thread

      causing pthread_mutex_trylock() to hang. In this case, we should

      just return EBUSY. Hence, we use pthread_mutex_trylock() to be

      able to return immediately.

    - We cannot just use trylock() and continue execution below, since

      this would generate an error and abort execution if the thread

      was overtaken and trylock() returned EBUSY . In this case, we

      instead just return EBUSY, since this is the expected behaviour

      of trylock().

   */

  if (try_lock)

  {

    error= pthread_mutex_trylock(&mp->mutex);

    if (error == EBUSY)

      return error;

  }

  else

    error= pthread_mutex_lock(&mp->mutex);

  if (error || (error=pthread_mutex_lock(&mp->global)))

  {

    fprintf(stderr,"Got error %d when trying to lock mutex at %s, line %d\n",

	    error, file, line);

    fflush(stderr);

    abort();

  }

  mp->thread= pthread_self();

  if (mp->count++)

  {

    fprintf(stderr,"safe_mutex: Error in thread libray: Got mutex at %s, \

line %d more than 1 time\n", file,line);

    fflush(stderr);

    abort();

  }

  mp->file= file;

  mp->line=line;

  pthread_mutex_unlock(&mp->global);

  return error;

}

int safe_mutex_unlock(safe_mutex_t *mp,const char *file, uint32_t line)

{

  int error;

  pthread_mutex_lock(&mp->global);

  if (mp->count == 0)

  {

    fprintf(stderr,"safe_mutex: Trying to unlock mutex that wasn't locked at %s, line %d\n            Last used at %s, line: %d\n",

	    file,line,mp->file ? mp->file : "",mp->line);

    fflush(stderr);

    abort();

  }

  if (!pthread_equal(pthread_self(),mp->thread))

  {

    fprintf(stderr,"safe_mutex: Trying to unlock mutex at %s, line %d  that was locked by another thread at: %s, line: %d\n",

	    file,line,mp->file,mp->line);

    fflush(stderr);

    abort();

  }

  mp->thread= 0;

  mp->count--;

  error=pthread_mutex_unlock(&mp->mutex);

  if (error)

  {

    fprintf(stderr,"safe_mutex: Got error: %d (%d) when trying to unlock mutex at %s, line %d\n", error, errno, file, line);

    fflush(stderr);

    abort();

  }

  pthread_mutex_unlock(&mp->global);

  return error;

}

int safe_cond_wait(pthread_cond_t *cond, safe_mutex_t *mp, const char *file,

		   uint32_t line)

{

  int error;

  pthread_mutex_lock(&mp->global);

  if (mp->count == 0)

  {

    fprintf(stderr,"safe_mutex: Trying to cond_wait on a unlocked mutex at %s, line %d\n",file,line);

    fflush(stderr);

    abort();

  }

  if (!pthread_equal(pthread_self(),mp->thread))

  {

    fprintf(stderr,"safe_mutex: Trying to cond_wait on a mutex at %s, line %d  that was locked by another thread at: %s, line: %d\n",

	    file,line,mp->file,mp->line);

    fflush(stderr);

    abort();

  }

  if (mp->count-- != 1)

  {

    fprintf(stderr,"safe_mutex:  Count was %d on locked mutex at %s, line %d\n",

	    mp->count+1, file, line);

    fflush(stderr);

    abort();

  }

  pthread_mutex_unlock(&mp->global);

  error=pthread_cond_wait(cond,&mp->mutex);

  pthread_mutex_lock(&mp->global);

  if (error)

  {

    fprintf(stderr,"safe_mutex: Got error: %d (%d) when doing a safe_mutex_wait at %s, line %d\n", error, errno, file, line);

    fflush(stderr);

    abort();

  }

  mp->thread=pthread_self();

  if (mp->count++)

  {

    fprintf(stderr,

	    "safe_mutex:  Count was %d in thread 0x%lx when locking mutex at %s, line %d\n",

	    mp->count-1, my_thread_dbug_id(), file, line);

    fflush(stderr);

    abort();

  }

  mp->file= file;

  mp->line=line;

  pthread_mutex_unlock(&mp->global);

  return error;

}

int safe_cond_timedwait(pthread_cond_t *cond, safe_mutex_t *mp,

			struct timespec *abstime,

			const char *file, uint32_t line)

{

  int error;

  pthread_mutex_lock(&mp->global);

  if (mp->count != 1 || !pthread_equal(pthread_self(),mp->thread))

  {

    fprintf(stderr,"safe_mutex: Trying to cond_wait at %s, line %d on a not hold mutex\n",file,line);

    fflush(stderr);

    abort();

  }

  mp->count--;					/* Mutex will be released */

  pthread_mutex_unlock(&mp->global);

  error=pthread_cond_timedwait(cond,&mp->mutex,abstime);

#ifdef EXTRA_DEBUG

  if (error && (error != EINTR && error != ETIMEDOUT && error != ETIME))

  {

    fprintf(stderr,"safe_mutex: Got error: %d (%d) when doing a safe_mutex_timedwait at %s, line %d\n", error, errno, file, line);

  }

#endif

  pthread_mutex_lock(&mp->global);

  mp->thread=pthread_self();

  if (mp->count++)

  {

    fprintf(stderr,

	    "safe_mutex:  Count was %d in thread 0x%lx when locking mutex at %s, line %d (error: %d (%d))\n",

	    mp->count-1, my_thread_dbug_id(), file, line, error, error);

    fflush(stderr);

    abort();

  }

  mp->file= file;

  mp->line=line;

  pthread_mutex_unlock(&mp->global);

  return error;

}

int safe_mutex_destroy(safe_mutex_t *mp, const char *file, uint32_t line)

{

  int error=0;

  if (!mp->file)

  {

    fprintf(stderr,

	    "safe_mutex: Trying to destroy unitialized mutex at %s, line %d\n",

	    file, line);

    fflush(stderr);

    abort();

  }

  if (mp->count != 0)

  {

    fprintf(stderr,"safe_mutex: Trying to destroy a mutex that was locked at %s, line %d at %s, line %d\n",

	    mp->file,mp->line, file, line);

    fflush(stderr);

    abort();

  }

  if (pthread_mutex_destroy(&mp->global))

    error=1;

  if (pthread_mutex_destroy(&mp->mutex))

    error=1;

  mp->file= 0;					/* Mark destroyed */

#ifdef SAFE_MUTEX_DETECT_DESTROY

  if (mp->info)

  {

    struct st_safe_mutex_info_t *info= mp->info;

    pthread_mutex_lock(&THR_LOCK_mutex);

    if (info->prev)

      info->prev->next = info->next;

    else

      safe_mutex_root = info->next;

    if (info->next)

      info->next->prev = info->prev;

    safe_mutex_count--;

    pthread_mutex_unlock(&THR_LOCK_mutex);

    free(info);

    mp->info= NULL;				/* Get crash if double free */

  }

#else

  thread_safe_sub(safe_mutex_count, 1, &THR_LOCK_mutex);

#endif /* SAFE_MUTEX_DETECT_DESTROY */

  return error;

}

/*

  Free global resources and check that all mutex has been destroyed

  SYNOPSIS

    safe_mutex_end()

    file		Print errors on this file

  NOTES

   In MySQL one may get one warning for a mutex created in my_thr_init.c

   This is ok, as this thread may not yet have been exited.

*/

void safe_mutex_end(int *)

{

  if (!safe_mutex_count)			/* safetly */

    pthread_mutex_destroy(&THR_LOCK_mutex);

#ifdef SAFE_MUTEX_DETECT_DESTROY

  if (!file)

    return;

  if (safe_mutex_count)

  {

    fprintf(file, "Warning: Not destroyed mutex: %lu\n", safe_mutex_count);

    (void) fflush(file);

  }

  {

    struct st_safe_mutex_info_t *ptr;

    for (ptr= safe_mutex_root ; ptr ; ptr= ptr->next)

    {

      fprintf(file, "\tMutex initiated at line %4u in '%s'\n",

	      ptr->init_line, ptr->init_file);

      (void) fflush(file);

    }

  }

#endif /* SAFE_MUTEX_DETECT_DESTROY */

}

#endif /* THREAD && SAFE_MUTEX */