Commit 3ea2ee35 authored by svoj@mysql.com/april.(none)'s avatar svoj@mysql.com/april.(none)
Browse files

BUG#25712 - insert delayed and check table run together report crashed 

            tables

In case system doesn't have native pread/pwrite calls (e.g. Windows)
and there is CHECK TABLE runs concurrently with another statement that
reads from a table, the table may be reported as crashed.

This is fixed by locking file descriptor when my_seek is executed on
MyISAM index file and emulated pread/pwrite may be executed concurrently.

Affects MyISAM tables on platforms that do not have native
pread/pwrite calls (e.g. Windows).

No deterministic test case for this bug.
parent 0c7631e7

myisam/mi_check.c

+7 −6
Original line number Diff line number Diff line
@@ -336,7 +336,7 @@ int chk_size(MI_CHECK *param, register MI_INFO *info) 
  flush_key_blocks(info->s->key_cache,

		   info->s->kfile, FLUSH_FORCE_WRITE);



  size=my_seek(info->s->kfile,0L,MY_SEEK_END,MYF(0));

  size= my_seek(info->s->kfile, 0L, MY_SEEK_END, MYF(MY_THREADSAFE));

  if ((skr=(my_off_t) info->state->key_file_length) != size)

  {

    if (skr > size)
@@ -595,7 +595,8 @@ static int chk_index_down(MI_CHECK *param, MI_INFO *info, MI_KEYDEF *keyinfo, 
  {

    /* purecov: begin tested */

    /* Give it a chance to fit in the real file size. */

    my_off_t max_length= my_seek(info->s->kfile, 0L, MY_SEEK_END, MYF(0));

    my_off_t max_length= my_seek(info->s->kfile, 0L, MY_SEEK_END,

                                 MYF(MY_THREADSAFE));

    mi_check_print_error(param, "Invalid key block position: %s  "

                         "key block size: %u  file_length: %s",

                         llstr(page, llbuff), keyinfo->block_length,
@@ -4039,10 +4040,10 @@ int test_if_almost_full(MI_INFO *info) 
{

  if (info->s->options & HA_OPTION_COMPRESS_RECORD)

    return 0;

  return (my_seek(info->s->kfile,0L,MY_SEEK_END,MYF(0))/10*9 >

	  (my_off_t) (info->s->base.max_key_file_length) ||

  return my_seek(info->s->kfile, 0L, MY_SEEK_END, MYF(MY_THREADSAFE)) / 10 * 9 >

         (my_off_t) info->s->base.max_key_file_length ||

         my_seek(info->dfile, 0L, MY_SEEK_END, MYF(0)) / 10 * 9 >

	  (my_off_t) info->s->base.max_data_file_length);

         (my_off_t) info->s->base.max_data_file_length;

}



	/* Recreate table with bigger more alloced record-data */

mysys/my_seek.c

+13 −2
Original line number Diff line number Diff line
@@ -24,7 +24,9 @@ 
  my_off_t pos     The expected position (absolute or relative)

  int whence       A direction parameter and one of 

                   {SEEK_SET, SEEK_CUR, SEEK_END}

  myf MyFlags      Not used.

  myf MyFlags      MY_THREADSAFE must be set in case my_seek may be mixed

                   with my_pread/my_pwrite calls and fd is shared among

                   threads.



  DESCRIPTION

    The my_seek  function  is a wrapper around the system call lseek and
@@ -51,6 +53,15 @@ my_off_t my_seek(File fd, my_off_t pos, int whence, 
		   whence, MyFlags));

  DBUG_ASSERT(pos != MY_FILEPOS_ERROR);		/* safety check */



#if defined(THREAD) && !defined(HAVE_PREAD)

  if (MyFlags & MY_THREADSAFE)

  {

    pthread_mutex_lock(&my_file_info[fd].mutex);

    newpos= lseek(fd, pos, whence);

    pthread_mutex_lock(&my_file_info[fd].mutex);

  }

  else

#endif

    newpos= lseek(fd, pos, whence);

  if (newpos == (os_off_t) -1)

  {