mariadb/storage/maria/ma_locking.c

/* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult 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 */

/*
  Locking of Maria-tables.
  Must be first request before doing any furter calls to any Maria function.
  Is used to allow many process use the same non transactional Maria table
*/

#include "ma_ftdefs.h"

	/* lock table by F_UNLCK, F_RDLCK or F_WRLCK */

int maria_lock_database(MARIA_HA *info, int lock_type)
{
  int error;
  uint count;
  MARIA_SHARE *share= info->s;
  DBUG_ENTER("maria_lock_database");
  DBUG_PRINT("enter",("lock_type: %d  old lock %d  r_locks: %u  w_locks: %u "
                      "global_changed:  %d  open_count: %u  name: '%s'",
                      lock_type, info->lock_type, share->r_locks,
                      share->w_locks,
                      share->global_changed, share->state.open_count,
                      share->index_file_name.str));
  if (share->options & HA_OPTION_READ_ONLY_DATA ||
      info->lock_type == lock_type)
    DBUG_RETURN(0);
  if (lock_type == F_EXTRA_LCK)                 /* Used by TMP tables */
  {
    ++share->w_locks;
    ++share->tot_locks;
    info->lock_type= lock_type;
    DBUG_RETURN(0);
  }

  error=0;
  pthread_mutex_lock(&share->intern_lock);
  if (share->kfile.file >= 0)		/* May only be false on windows */
  {
    switch (lock_type) {
    case F_UNLCK:
      maria_ftparser_call_deinitializer(info);
      if (info->lock_type == F_RDLCK)
      {
	count= --share->r_locks;
        if (share->lock_restore_status)
          (*share->lock_restore_status)(info);
      }
      else
      {
	count= --share->w_locks;
        if (share->lock.update_status)
          _ma_update_status_with_lock(info);
      }
      --share->tot_locks;
      if (info->lock_type == F_WRLCK && !share->w_locks)
      {
        /* pages of transactional tables get flushed at Checkpoint */
        if (!share->base.born_transactional && !share->temporary &&
            _ma_flush_table_files(info,
                                  share->delay_key_write ? MARIA_FLUSH_DATA :
                                  MARIA_FLUSH_DATA | MARIA_FLUSH_INDEX,
                                  FLUSH_KEEP, FLUSH_KEEP))
          error= my_errno;
      }
      if (info->opt_flag & (READ_CACHE_USED | WRITE_CACHE_USED))
      {
	if (end_io_cache(&info->rec_cache))
	{
	  error= my_errno;
          _ma_set_fatal_error(share, error);
	}
      }
      if (!count)
      {
	DBUG_PRINT("info",("changed: %u  w_locks: %u",
			   (uint) share->changed, share->w_locks));
	if (share->changed && !share->w_locks)
	{
#ifdef HAVE_MMAP
          if ((share->mmaped_length !=
               share->state.state.data_file_length) &&
              (share->nonmmaped_inserts > MAX_NONMAPPED_INSERTS))
          {
            if (share->lock_key_trees)
              rw_wrlock(&share->mmap_lock);
            _ma_remap_file(info, share->state.state.data_file_length);
            share->nonmmaped_inserts= 0;
            if (share->lock_key_trees)
              rw_unlock(&share->mmap_lock);
          }
#endif
#ifdef EXTERNAL_LOCKING
	  share->state.process= share->last_process=share->this_process;
	  share->state.unique=   info->last_unique=  info->this_unique;
	  share->state.update_count= info->last_loop= ++info->this_loop;
#endif
          /* transactional tables rather flush their state at Checkpoint */
          if (!share->base.born_transactional)
          {
            if (_ma_state_info_write_sub(share->kfile.file, &share->state,
                                         MA_STATE_INFO_WRITE_DONT_MOVE_OFFSET))
              error= my_errno;
            else
            {
              /* A value of 0 means below means "state flushed" */
              share->changed= 0;
            }
          }
	  if (maria_flush)
	  {
            if (_ma_sync_table_files(info))
	      error= my_errno;
	  }
	  else
	    share->not_flushed=1;
	  if (error)
            _ma_set_fatal_error(share, error);
	}
      }
      info->opt_flag&= ~(READ_CACHE_USED | WRITE_CACHE_USED);
      info->lock_type= F_UNLCK;
      break;
    case F_RDLCK:
      if (info->lock_type == F_WRLCK)
      {
        /*
          Change RW to READONLY

          mysqld does not turn write locks to read locks,
          so we're never here in mysqld.
        */
	share->w_locks--;
	share->r_locks++;
	info->lock_type=lock_type;
	break;
      }
#ifdef MARIA_EXTERNAL_LOCKING
      if (!share->r_locks && !share->w_locks)
      {
        /* note that a transactional table should not do this */
	if (_ma_state_info_read_dsk(share->kfile.file, &share->state))
	{
	  error=my_errno;
	  break;
	}
      }
#endif
      VOID(_ma_test_if_changed(info));
      share->r_locks++;
      share->tot_locks++;
      info->lock_type=lock_type;
      break;
    case F_WRLCK:
      if (info->lock_type == F_RDLCK)
      {						/* Change READONLY to RW */
	if (share->r_locks == 1)
	{
	  share->r_locks--;
	  share->w_locks++;
	  info->lock_type=lock_type;
	  break;
	}
      }
#ifdef MARIA_EXTERNAL_LOCKING
      if (!(share->options & HA_OPTION_READ_ONLY_DATA))
      {
	if (!share->w_locks)
	{
	  if (!share->r_locks)
	  {
            /*
              Note that transactional tables should not do this.
              If we enabled this code, we should make sure to skip it if
              born_transactional is true. We should not test
              now_transactional to decide if we can call
              _ma_state_info_read_dsk(), because it can temporarily be 0
              (TRUNCATE on a partitioned table) and thus it would make a state
              modification below without mutex, confusing a concurrent
              checkpoint running.
              Even if this code was enabled only for non-transactional tables:
              in scenario LOCK TABLE t1 WRITE; INSERT INTO t1; DELETE FROM t1;
              state on disk read by DELETE is obsolete as it was not flushed
              at the end of INSERT. MyISAM same. It however causes no issue as
              maria_delete_all_rows() calls _ma_reset_status() thus is not
              influenced by the obsolete read values.
            */
	    if (_ma_state_info_read_dsk(share->kfile.file, &share->state))
	    {
	      error=my_errno;
	      break;
	    }
	  }
	}
      }
#endif /* defined(MARIA_EXTERNAL_LOCKING) */
      VOID(_ma_test_if_changed(info));

      info->lock_type=lock_type;
      info->invalidator=share->invalidator;
      share->w_locks++;
      share->tot_locks++;
      break;
    default:
      DBUG_ASSERT(0);
      break;				/* Impossible */
    }
  }
#ifdef __WIN__
  else
  {
    /*
       Check for bad file descriptors if this table is part
       of a merge union. Failing to capture this may cause
       a crash on windows if the table is renamed and
       later on referenced by the merge table.
     */
    if( info->owned_by_merge && (info->s)->kfile.file < 0 )
    {
      error = HA_ERR_NO_SUCH_TABLE;
    }
  }
#endif
  pthread_mutex_unlock(&share->intern_lock);
  DBUG_RETURN(error);
} /* maria_lock_database */


/****************************************************************************
 ** functions to read / write the state
****************************************************************************/

int _ma_readinfo(register MARIA_HA *info __attribute__ ((unused)),
                 int lock_type __attribute__ ((unused)),
                 int check_keybuffer __attribute__ ((unused)))
{
#ifdef MARIA_EXTERNAL_LOCKING
  DBUG_ENTER("_ma_readinfo");

  if (info->lock_type == F_UNLCK)
  {
    MARIA_SHARE *share= info->s;
    if (!share->tot_locks)
    {
      /* should not be done for transactional tables */
      if (_ma_state_info_read_dsk(share->kfile.file, &share->state))
      {
        if (!my_errno)
          my_errno= HA_ERR_FILE_TOO_SHORT;
	DBUG_RETURN(1);
      }
    }
    if (check_keybuffer)
      VOID(_ma_test_if_changed(info));
    info->invalidator=share->invalidator;
  }
  else if (lock_type == F_WRLCK && info->lock_type == F_RDLCK)
  {
    my_errno=EACCES;				/* Not allowed to change */
    DBUG_RETURN(-1);				/* when have read_lock() */
  }
  DBUG_RETURN(0);
#else
  return 0;
#endif /* defined(MARIA_EXTERNAL_LOCKING) */
} /* _ma_readinfo */


/*
  Every isam-function that uppdates the isam-database MUST end with this
  request

  NOTES
    my_errno is not changed if this succeeds!
*/

int _ma_writeinfo(register MARIA_HA *info, uint operation)
{
  int error,olderror;
  MARIA_SHARE *share= info->s;
  DBUG_ENTER("_ma_writeinfo");
  DBUG_PRINT("info",("operation: %u  tot_locks: %u", operation,
		     share->tot_locks));

  error=0;
  if (share->tot_locks == 0 && !share->base.born_transactional)
  {
    /* transactional tables flush their state at Checkpoint */
    if (operation)
    {					/* Two threads can't be here */
      olderror= my_errno;               /* Remember last error */

#ifdef EXTERNAL_LOCKING
      /*
        The following only makes sense if we want to be allow two different
        processes access the same table at the same time
      */
      share->state.process= share->last_process=   share->this_process;
      share->state.unique=  info->last_unique=	   info->this_unique;
      share->state.update_count= info->last_loop= ++info->this_loop;
#endif

      if ((error=
           _ma_state_info_write_sub(share->kfile.file,
                                    &share->state,
                                    MA_STATE_INFO_WRITE_DONT_MOVE_OFFSET)))
	olderror=my_errno;
#ifdef __WIN__
      if (maria_flush)
      {
	_commit(share->kfile.file);
	_commit(info->dfile.file);
      }
#endif
      my_errno=olderror;
    }
  }
  else if (operation)
    share->changed= 1;			/* Mark keyfile changed */
  DBUG_RETURN(error);
} /* _ma_writeinfo */


/*
  Test if an external process has changed the database
  (Should be called after readinfo)
*/

int _ma_test_if_changed(register MARIA_HA *info)
{
#ifdef EXTERNAL_LOCKING
  MARIA_SHARE *share= info->s;
  if (share->state.process != share->last_process ||
      share->state.unique  != info->last_unique ||
      share->state.update_count != info->last_loop)
  {						/* Keyfile has changed */
    DBUG_PRINT("info",("index file changed"));
    if (share->state.process != share->this_process)
      VOID(flush_pagecache_blocks(share->pagecache, &share->kfile,
                                  FLUSH_RELEASE));
    share->last_process=share->state.process;
    info->last_unique=	share->state.unique;
    info->last_loop=	share->state.update_count;
    info->update|=	HA_STATE_WRITTEN;	/* Must use file on next */
    info->data_changed= 1;			/* For maria_is_changed */
    return 1;
  }
#endif
  return (!(info->update & HA_STATE_AKTIV) ||
	  (info->update & (HA_STATE_WRITTEN | HA_STATE_DELETED |
			   HA_STATE_KEY_CHANGED)));
} /* _ma_test_if_changed */


/*
  Put a mark in the .MAI file that someone is updating the table

  DOCUMENTATION
  state.open_count in the .MAI file is used the following way:
  - For the first change of the .MYI file in this process open_count is
    incremented by _ma_mark_file_changed(). (We have a write lock on the file
    when this happens)
  - In maria_close() it's decremented by _ma_decrement_open_count() if it
    was incremented in the same process.

  This mean that if we are the only process using the file, the open_count
  tells us if the MARIA file wasn't properly closed. (This is true if
  my_disable_locking is set).

  open_count is not maintained on disk for temporary tables.
*/

#define _MA_ALREADY_MARKED_FILE_CHANGED                                 \
  ((share->state.changed & STATE_CHANGED) && share->global_changed)

int _ma_mark_file_changed(register MARIA_SHARE *share)
{
  if (!share->base.born_transactional)
  {
    if (!_MA_ALREADY_MARKED_FILE_CHANGED)
      return _ma_mark_file_changed_now(share);
  }
  else
  {
    /*
      For transactional tables, the table is marked changed when the first page
      is written. Here we just mark the state to be updated so that caller
      can do 'anaylze table' and find that is has changed before any pages
      are written.
    */
    if (! test_all_bits(share->state.changed,
                        (STATE_CHANGED | STATE_NOT_ANALYZED |
                         STATE_NOT_OPTIMIZED_KEYS)))
    {
      pthread_mutex_lock(&share->intern_lock);    
      share->state.changed|=(STATE_CHANGED | STATE_NOT_ANALYZED |
                             STATE_NOT_OPTIMIZED_KEYS);
      pthread_mutex_unlock(&share->intern_lock);    
    }
  }
  return 0;
}

int _ma_mark_file_changed_now(register MARIA_SHARE *share)
{
  uchar buff[3];
  int error= 1;
  DBUG_ENTER("_ma_mark_file_changed_now");

  if (_MA_ALREADY_MARKED_FILE_CHANGED)
    DBUG_RETURN(0);
  pthread_mutex_lock(&share->intern_lock); /* recheck under mutex */
  if (! _MA_ALREADY_MARKED_FILE_CHANGED)
  {
    share->state.changed|=(STATE_CHANGED | STATE_NOT_ANALYZED |
			   STATE_NOT_OPTIMIZED_KEYS);
    if (!share->global_changed)
    {
      share->changed= share->global_changed= 1;
      share->state.open_count++;
    }
    /*
      Temp tables don't need an open_count as they are removed on crash.
      In theory transactional tables are fixed by log-based recovery, so don't
      need an open_count either, but if recovery has failed and logs have been
      removed (by maria-force-start-after-recovery-failures), we still need to
      detect dubious tables.
      If we didn't maintain open_count on disk for a table, after a crash
      we wouldn't know if it was closed at crash time (thus does not need a
      check) or not. So we would have to check all tables: overkill.
    */
    if (!share->temporary)
    {
      mi_int2store(buff,share->state.open_count);
      buff[2]=1;				/* Mark that it's changed */
      if (my_pwrite(share->kfile.file, buff, sizeof(buff),
                    sizeof(share->state.header) +
                    MARIA_FILE_OPEN_COUNT_OFFSET,
                    MYF(MY_NABP)))
        goto err;
    }
    /* Set uuid of file if not yet set (zerofilled file) */
    if (share->base.born_transactional &&
        !(share->state.changed & STATE_NOT_MOVABLE))
    {
      /* Lock table to current installation */
      if (_ma_set_uuid(share, 0) ||
          (share->state.create_rename_lsn == LSN_NEEDS_NEW_STATE_LSNS &&
           _ma_update_state_lsns_sub(share, LSN_IMPOSSIBLE,
                                     trnman_get_min_trid(),
                                     TRUE, TRUE)))
        goto err;
      share->state.changed|= STATE_NOT_MOVABLE;
    }
  }
  error= 0;
err:
  pthread_mutex_unlock(&share->intern_lock);
  DBUG_RETURN(error);
#undef _MA_ALREADY_MARKED_FILE_CHANGED
}

/*
  Check that a region is all zero

  SYNOPSIS
    check_if_zero()
    pos		Start of memory to check
    length	length of memory region

  NOTES
    Used mainly to detect rows with wrong extent information
*/

my_bool _ma_check_if_zero(uchar *pos, size_t length)
{
  uchar *end;
  for (end= pos+ length; pos != end ; pos++)
    if (pos[0] != 0)
      return 1;
  return 0;
}

/*
  This is only called by close or by extra(HA_FLUSH) if the OS has the pwrite()
  call.  In these context the following code should be safe!
 */

int _ma_decrement_open_count(MARIA_HA *info, my_bool lock_tables)
{
  uchar buff[2];
  register MARIA_SHARE *share= info->s;
  int lock_error=0,write_error=0;
  DBUG_ENTER("_ma_decrement_open_count");

  if (share->global_changed)
  {
    uint old_lock=info->lock_type;
    share->global_changed=0;
    lock_error= (my_disable_locking || ! lock_tables ? 0 :
                 maria_lock_database(info, F_WRLCK));
    /* Its not fatal even if we couldn't get the lock ! */
    if (share->state.open_count > 0)
    {
      share->state.open_count--;
      share->changed= 1;                        /* We have to update state */
      /*
        For temporary tables that will just be deleted, we don't have
        to decrement state. For transactional tables the state will be
        updated in maria_close().
      */

      if (!share->temporary && !share->now_transactional)
      {
        mi_int2store(buff,share->state.open_count);
        write_error= (int) my_pwrite(share->kfile.file, buff, sizeof(buff),
                                     sizeof(share->state.header) +
                                     MARIA_FILE_OPEN_COUNT_OFFSET,
                                     MYF(MY_NABP));
      }
    }
    if (!lock_error && !my_disable_locking && lock_tables)
      lock_error=maria_lock_database(info,old_lock);
  }
  DBUG_RETURN(test(lock_error || write_error));
}


/** @brief mark file as crashed */

void _ma_mark_file_crashed(MARIA_SHARE *share)
{
  uchar buff[2];
  DBUG_ENTER("_ma_mark_file_crashed");

  share->state.changed|= STATE_CRASHED;
  mi_int2store(buff, share->state.changed);
  /*
    We can ignore the errors, as if the mark failed, there isn't anything
    else we can do;  The user should already have got an error that the
    table was crashed.
  */
  (void) my_pwrite(share->kfile.file, buff, sizeof(buff),
                   sizeof(share->state.header) +
                   MARIA_FILE_CHANGED_OFFSET,
                   MYF(MY_NABP));
  DBUG_VOID_RETURN;
}

/*
  Handle a fatal error

  - Mark the table as crashed
  - Print an error message, if we had not issued an error message before
    that the table had been crashed.
  - set my_errno to error
  - If 'maria_assert_if_crashed_table is set, then assert.
*/

void _ma_set_fatal_error(MARIA_SHARE *share, int error)
{
  DBUG_PRINT("error", ("error: %d", error));
  maria_mark_crashed_share(share);
  if (!(share->state.changed & STATE_CRASHED_PRINTED))
  {
    share->state.changed|= STATE_CRASHED_PRINTED;
    maria_print_error(share, error);
  }
  my_errno= error;
  DBUG_ASSERT(!maria_assert_if_crashed_table);
}


/**
   @brief Set uuid of for a Maria file

   @fn _ma_set_uuid()
   @param share		Maria share
   @param reset_uuid    Instead of setting file to maria_uuid, set it to
			0 to mark it as movable
*/

my_bool _ma_set_uuid(MARIA_SHARE *share, my_bool reset_uuid)
{
  uchar buff[MY_UUID_SIZE], *uuid;

  uuid= maria_uuid;
  if (reset_uuid)
  {
    bzero(buff, sizeof(buff));
    uuid= buff;
  }
  return (my_bool) my_pwrite(share->kfile.file, uuid, MY_UUID_SIZE,
                             mi_uint2korr(share->state.header.base_pos),
                             MYF(MY_NABP));
}