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Bug#15669

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"Test case 'csv' produces incorrect result on OpenBSD"
  mmapped pages were not being invalidated when writes occurred to the
  file vi a fd i/o operation. 
  Force explicit invalidation and not rely on implicit invalidation.
This commit is contained in:
acurtis/antony@xiphis.org/ltantony.xiphis.org 2006-08-01 09:36:34 -07:00
parent 0dab0516af
commit a1936d28a6
1 changed files with 56 additions and 8 deletions
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64
sql/examples/ha_tina.cc
View file

@ -101,13 +101,34 @@ static byte* tina_get_key(TINA_SHARE *share,uint *length,
return (byte*) share->table_name;
}
int free_mmap(TINA_SHARE *share)
{
DBUG_ENTER("ha_tina::free_mmap");
if (share->mapped_file)
{
/*
Invalidate the mapped in pages. Some operating systems (eg OpenBSD)
would reuse already cached pages even if the file has been altered
using fd based I/O. This may be optimized by perhaps only invalidating
the last page but optimization of deprecated code is not important.
*/
msync(share->mapped_file, 0, MS_INVALIDATE);
if (munmap(share->mapped_file, share->file_stat.st_size))
DBUG_RETURN(1);
}
share->mapped_file= NULL;
DBUG_RETURN(0);
}
/*
Reloads the mmap file.
*/
int get_mmap(TINA_SHARE *share, int write)
{
DBUG_ENTER("ha_tina::get_mmap");
if (share->mapped_file && munmap(share->mapped_file, share->file_stat.st_size))
if (free_mmap(share))
DBUG_RETURN(1);
if (my_fstat(share->data_file, &share->file_stat, MYF(MY_WME)) == -1)
@ -230,8 +251,7 @@ static int free_share(TINA_SHARE *share)
int result_code= 0;
if (!--share->use_count){
/* Drop the mapped file */
if (share->mapped_file)
munmap(share->mapped_file, share->file_stat.st_size);
free_mmap(share);
result_code= my_close(share->data_file,MYF(0));
hash_delete(&tina_open_tables, (byte*) share);
thr_lock_delete(&share->lock);
@ -493,6 +513,13 @@ int ha_tina::write_row(byte * buf)
size= encode_quote(buf);
/*
we are going to alter the file so we must invalidate the in memory pages
otherwise we risk a race between the in memory pages and the disk pages.
*/
if (free_mmap(share))
DBUG_RETURN(-1);
if (my_write(share->data_file, buffer.ptr(), size, MYF(MY_WME | MY_NABP)))
DBUG_RETURN(-1);
@ -534,8 +561,26 @@ int ha_tina::update_row(const byte * old_data, byte * new_data)
if (chain_append())
DBUG_RETURN(-1);
/*
we are going to alter the file so we must invalidate the in memory pages
otherwise we risk a race between the in memory pages and the disk pages.
*/
if (free_mmap(share))
DBUG_RETURN(-1);
if (my_write(share->data_file, buffer.ptr(), size, MYF(MY_WME | MY_NABP)))
DBUG_RETURN(-1);
/*
Ok, this is means that we will be doing potentially bad things
during a bulk update on some OS'es. Ideally, we should extend the length
of the file, redo the mmap and then write all the updated rows. Upon
finishing the bulk update, truncate the file length to the final length.
Since this code is all being deprecated, not point now to optimize.
*/
if (get_mmap(share, 0) > 0)
DBUG_RETURN(-1);
DBUG_RETURN(0);
}
@ -812,15 +857,14 @@ int ha_tina::rnd_end()
length= length - (size_t)(ptr->end - ptr->begin);
}
/* Invalidate all cached mmap pages */
if (free_mmap(share))
DBUG_RETURN(-1);
/* Truncate the file to the new size */
if (my_chsize(share->data_file, length, 0, MYF(MY_WME)))
DBUG_RETURN(-1);
if (munmap(share->mapped_file, length))
DBUG_RETURN(-1);
/* We set it to null so that get_mmap() won't try to unmap it */
share->mapped_file= NULL;
if (get_mmap(share, 0) > 0)
DBUG_RETURN(-1);
}
@ -838,6 +882,10 @@ int ha_tina::delete_all_rows()
if (!records_is_known)
return (my_errno=HA_ERR_WRONG_COMMAND);
/* Invalidate all cached mmap pages */
if (free_mmap(share))
DBUG_RETURN(-1);
int rc= my_chsize(share->data_file, 0, 0, MYF(MY_WME));
if (get_mmap(share, 0) > 0)