MDEV-4011 Added per thread memory counting and usage

Base code and idea from a patch from by plinux at Taobao.

The idea is that we mark all memory that are thread specific with MY_THREAD_SPECIFIC.
Memory counting is done per thread in the my_malloc_size_cb_func callback function from my_malloc().
There are plenty of new asserts to ensure that for a debug server the counting is correct.

Information_schema.processlist gets two new columns: MEMORY_USED and EXAMINED_ROWS.
- The later is there mainly to show how query is progressing.

The following changes in interfaces was needed to get this to work:
- init_alloc_root() amd init_sql_alloc() has extra option so that one can mark memory with MY_THREAD_SPECIFIC
- One now have to use alloc_root_set_min_malloc() to set min memory to be allocated by alloc_root()
- my_init_dynamic_array()  has extra option so that one can mark memory with MY_THREAD_SPECIFIC
- my_net_init() has extra option so that one can mark memory with MY_THREAD_SPECIFIC
- Added flag for hash_init() so that one can mark hash table to be thread specific.
- Added flags to init_tree() so that one can mark tree to be thread specific.
- Removed with_delete option to init_tree(). Now one should instead use MY_TREE_WITH_DELETE_FLAG.
- Added flag to Warning_info::Warning_info() if the structure should be fully initialized.
- String elements can now be marked as thread specific.
- Internal HEAP tables are now marking it's memory as MY_THREAD_SPECIFIC.
- Changed type of myf from int to ulong, as this is always a set of bit flags.

Other things:
- Removed calls to net_end() and thd->cleanup() as these are now done in ~THD()
- We now also show EXAMINED_ROWS in SHOW PROCESSLIST
- Added new variable 'memory_used'
- Fixed bug where kill_threads_for_user() was using the wrong mem_root to allocate memory.
- Removed calls to the obsoleted function init_dynamic_array()
- Use set_current_thd() instead of my_pthread_setspecific_ptr(THR_THD,...)


client/completion_hash.cc:
  Updated call to init_alloc_root()
client/mysql.cc:
  Updated call to init_alloc_root()
client/mysqlbinlog.cc:
  init_dynamic_array() -> my_init_dynamic_array()
  Updated call to init_alloc_root()
client/mysqlcheck.c:
  Updated call to my_init_dynamic_array()
client/mysqldump.c:
  Updated call to init_alloc_root()
client/mysqltest.cc:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
  Fixed compiler warnings
extra/comp_err.c:
  Updated call to my_init_dynamic_array()
extra/resolve_stack_dump.c:
  Updated call to my_init_dynamic_array()
include/hash.h:
  Added HASH_THREAD_SPECIFIC
include/heap.h:
  Added flag is internal temporary table.
include/my_dir.h:
  Safety fix: Ensure that MY_DONT_SORT and MY_WANT_STAT don't interfer with other mysys flags
include/my_global.h:
  Changed type of myf from int to ulong, as this is always a set of bit flags.
include/my_sys.h:
  Added MY_THREAD_SPECIFIC and MY_THREAD_MOVE
  Added malloc_flags to DYNAMIC_ARRAY
  Added extra mysys flag argument to my_init_dynamic_array()
  Removed deprecated functions init_dynamic_array() and my_init_dynamic_array.._ci
  Updated paramaters for init_alloc_root()
include/my_tree.h:
  Added my_flags to allow one to use MY_THREAD_SPECIFIC with hash tables.
  Removed with_delete. One should now instead use MY_TREE_WITH_DELETE_FLAG
  Updated parameters to init_tree()
include/myisamchk.h:
  Added malloc_flags to allow one to use MY_THREAD_SPECIFIC for checks.
include/mysql.h:
  Added MYSQL_THREAD_SPECIFIC_MALLOC
  Used 'unused1' to mark memory as thread specific.
include/mysql.h.pp:
  Updated file
include/mysql_com.h:
  Used 'unused1' to mark memory as thread specific.
  Updated parameters for my_net_init()
libmysql/libmysql.c:
  Updated call to init_alloc_root() to mark memory thread specific.
libmysqld/emb_qcache.cc:
  Updated call to init_alloc_root()
libmysqld/lib_sql.cc:
  Updated call to init_alloc_root()
mysql-test/r/create.result:
  Updated results
mysql-test/r/user_var.result:
  Updated results
mysql-test/suite/funcs_1/datadict/processlist_priv.inc:
  Update to handle new format of SHOW PROCESSLIST
mysql-test/suite/funcs_1/datadict/processlist_val.inc:
  Update to handle new format of SHOW PROCESSLIST
mysql-test/suite/funcs_1/r/is_columns_is.result:
  Update to handle new format of SHOW PROCESSLIST
mysql-test/suite/funcs_1/r/processlist_priv_no_prot.result:
  Updated results
mysql-test/suite/funcs_1/r/processlist_val_no_prot.result:
  Updated results
mysql-test/t/show_explain.test:
  Fixed usage of debug variable so that one can run test with --debug
mysql-test/t/user_var.test:
  Added test of memory_usage variable.
mysys/array.c:
  Added extra my_flags option to init_dynamic_array() and init_dynamic_array2() so that one can mark memory with MY_THREAD_SPECIFIC
  All allocated memory is marked with the given my_flags.
  Removed obsolete function init_dynamic_array()
mysys/default.c:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
mysys/hash.c:
  Updated call to my_init_dynamic_array_ci().
  Allocated memory is marked with MY_THREAD_SPECIFIC if HASH_THREAD_SPECIFIC is used.
mysys/ma_dyncol.c:
  init_dynamic_array() -> my_init_dynamic_array()
  Added #if to get rid of compiler warnings
mysys/mf_tempdir.c:
  Updated call to my_init_dynamic_array()
mysys/my_alloc.c:
  Added extra parameter to init_alloc_root() so that one can mark memory with MY_THREAD_SPECIFIC
  Extend MEM_ROOT with a flag if memory is thread specific.
  This is stored in block_size, to keep the size of the MEM_ROOT object identical as before.
  Allocated memory is marked with MY_THREAD_SPECIFIC if used with init_alloc_root()
mysys/my_chmod.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_chsize.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_copy.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_create.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_delete.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_error.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_fopen.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_fstream.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_getwd.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_lib.c:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
  Updated DBUG_PRINT because of change of myf type
mysys/my_lock.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_malloc.c:
  Store at start of each allocated memory block the size of the block and if the block is thread specific.
  Call malloc_size_cb_func, if set, with the memory allocated/freed.
  Updated DBUG_PRINT because of change of myf type
mysys/my_open.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_pread.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_read.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_redel.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_rename.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_seek.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_sync.c:
  Updated DBUG_PRINT because of change of myf type
mysys/my_thr_init.c:
  Ensure that one can call my_thread_dbug_id() even if thread is not properly initialized.
mysys/my_write.c:
  Updated DBUG_PRINT because of change of myf type
mysys/mysys_priv.h:
  Updated parameters to sf_malloc and sf_realloc()
mysys/safemalloc.c:
  Added checking that for memory marked with MY_THREAD_SPECIFIC that it's the same thread that is allocation and freeing the memory.
  Added sf_malloc_dbug_id() to allow MariaDB to specify which THD is handling the memory.
  Added my_flags arguments to sf_malloc() and sf_realloc() to be able to mark memory with MY_THREAD_SPECIFIC.
  Added sf_report_leaked_memory() to get list of memory not freed by a thread.
mysys/tree.c:
  Added flags to init_tree() so that one can mark tree to be thread specific.
  Removed with_delete option to init_tree(). Now one should instead use MY_TREE_WITH_DELETE_FLAG.
  Updated call to init_alloc_root()
  All allocated memory is marked with the given malloc flags
mysys/waiting_threads.c:
  Updated call to my_init_dynamic_array()
sql-common/client.c:
  Updated call to init_alloc_root() and my_net_init() to mark memory thread specific.
  Updated call to my_init_dynamic_array().
  Added MYSQL_THREAD_SPECIFIC_MALLOC so that client can mark memory as MY_THREAD_SPECIFIC.
sql-common/client_plugin.c:
  Updated call to init_alloc_root()
sql/debug_sync.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/event_scheduler.cc:
  Removed calls to net_end() as this is now done in ~THD()
  Call set_current_thd() to ensure that memory is assigned to right thread.
sql/events.cc:
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/filesort.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/filesort_utils.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/ha_ndbcluster.cc:
  Updated call to init_alloc_root()
  Updated call to my_net_init()
  Removed calls to net_end() and thd->cleanup() as these are now done in ~THD()
sql/ha_ndbcluster_binlog.cc:
  Updated call to my_net_init()
  Updated call to init_sql_alloc()
  Removed calls to net_end() and thd->cleanup() as these are now done in ~THD()
sql/ha_partition.cc:
  Updated call to init_alloc_root()
sql/handler.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
  Added missing call to my_dir_end()
sql/item_func.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/item_subselect.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/item_sum.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/log.cc:
  More DBUG
  Updated call to init_alloc_root()
sql/mdl.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/mysqld.cc:
  Added total_memory_used
  Updated call to init_alloc_root()
  Move mysql_cond_broadcast() before my_thread_end()
  Added mariadb_dbug_id() to count memory per THD instead of per thread.
  Added my_malloc_size_cb_func() callback function for my_malloc() to count memory.
  Move initialization of mysqld_server_started and mysqld_server_initialized earlier.
  Updated call to my_init_dynamic_array().
  Updated call to my_net_init().
  Call my_pthread_setspecific_ptr(THR_THD,...) to ensure that memory is assigned to right thread.
  Added status variable 'memory_used'.
  Updated call to init_alloc_root()
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/mysqld.h:
  Added set_current_thd()
sql/net_serv.cc:
  Added new parameter to my_net_init() so that one can mark memory with MY_THREAD_SPECIFIC.
  Store in net->thread_specific_malloc if memory is thread specific.
  Mark memory to be thread specific if requested.
sql/opt_range.cc:
  Updated call to my_init_dynamic_array()
  Updated call to init_sql_alloc()
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/opt_subselect.cc:
  Updated call to init_sql_alloc() to mark memory thread specific.
sql/protocol.cc:
  Fixed compiler warning
sql/records.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/rpl_filter.cc:
  Updated call to my_init_dynamic_array()
sql/rpl_handler.cc:
  Updated call to my_init_dynamic_array2()
sql/rpl_handler.h:
  Updated call to init_sql_alloc()
sql/rpl_mi.cc:
  Updated call to my_init_dynamic_array()
sql/rpl_tblmap.cc:
  Updated call to init_alloc_root()
sql/rpl_utility.cc:
  Updated call to my_init_dynamic_array()
sql/slave.cc:
  Initialize things properly before calling functions that allocate memory.
  Removed calls to net_end() as this is now done in ~THD()
sql/sp_head.cc:
  Updated call to init_sql_alloc()
  Updated call to my_init_dynamic_array()
  Added parameter to warning_info() that it should be fully initialized.
sql/sp_pcontext.cc:
  Updated call to my_init_dynamic_array()
sql/sql_acl.cc:
  Updated call to init_sql_alloc()
  Updated call to my_init_dynamic_array()
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_admin.cc:
  Added parameter to warning_info() that it should be fully initialized.
sql/sql_analyse.h:
  Updated call to init_tree() to mark memory thread specific.
sql/sql_array.h:
  Updated call to my_init_dynamic_array() to mark memory thread specific.
sql/sql_audit.cc:
  Updated call to my_init_dynamic_array()
sql/sql_base.cc:
  Updated call to init_sql_alloc()
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_cache.cc:
  Updated comment
sql/sql_class.cc:
  Added parameter to warning_info() that not initialize it until THD is fully created.
  Updated call to init_sql_alloc()
  Mark THD::user_vars has to be thread specific.
  Updated call to my_init_dynamic_array()
  Ensure that memory allocated by THD is assigned to the THD.
  More DBUG
  Always acll net_end() in ~THD()
  Assert that all memory signed to this THD is really deleted at ~THD.
  Fixed set_status_var_init() to not reset memory_used.
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_class.h:
  Added MY_THREAD_SPECIFIC to allocated memory.
  Added malloc_size to THD to record allocated memory per THD.
sql/sql_delete.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/sql_error.cc:
  Added 'initialize' parameter to Warning_info() to say if should allocate memory for it's structures.
  This is used by THD::THD() to not allocate memory until THD is ready.
  Added Warning_info::free_memory()
sql/sql_error.h:
  Updated Warning_info() class.
sql/sql_handler.cc:
  Updated call to init_alloc_root() to mark memory thread specific.
sql/sql_insert.cc:
  More DBUG
sql/sql_join_cache.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/sql_lex.cc:
  Updated call to my_init_dynamic_array()
sql/sql_lex.h:
  Updated call to my_init_dynamic_array()
sql/sql_load.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/sql_parse.cc:
  Removed calls to net_end() and thd->cleanup() as these are now done in ~THD()
  Ensure that examined_row_count() is reset before query.
  Fixed bug where kill_threads_for_user() was using the wrong mem_root to allocate memory.
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
  Don't restore thd->status_var.memory_used when restoring thd->status_var
sql/sql_plugin.cc:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
  Don't allocate THD on the stack, as this causes problems with valgrind when doing thd memory counting.
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_prepare.cc:
  Added parameter to warning_info() that it should be fully initialized.
  Updated call to init_sql_alloc() to mark memory thread specific.
sql/sql_reload.cc:
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_select.cc:
  Updated call to my_init_dynamic_array() and init_sql_alloc() to mark memory thread specific.
  Added MY_THREAD_SPECIFIC to allocated memory.
  More DBUG
sql/sql_servers.cc:
  Updated call to init_sql_alloc() to mark memory some memory thread specific.
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_show.cc:
  Updated call to my_init_dynamic_array()
  Mark my_dir() memory thread specific.
  Use my_pthread_setspecific_ptr(THR_THD,...) to mark that allocated memory should be allocated to calling thread.
  More DBUG.
  Added malloc_size and examined_row_count to SHOW PROCESSLIST.
  Added MY_THREAD_SPECIFIC to allocated memory.
  Updated call to init_sql_alloc()
  Added parameter to warning_info() that it should be fully initialized.
sql/sql_statistics.cc:
  Fixed compiler warning
sql/sql_string.cc:
  String elements can now be marked as thread specific.
sql/sql_string.h:
  String elements can now be marked as thread specific.
sql/sql_table.cc:
  Updated call to init_sql_alloc() and my_malloc() to mark memory thread specific
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
  Fixed compiler warning
sql/sql_test.cc:
  Updated call to my_init_dynamic_array() to mark memory thread specific.
sql/sql_trigger.cc:
  Updated call to init_sql_alloc()
sql/sql_udf.cc:
  Updated call to init_sql_alloc()
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/sql_update.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
sql/table.cc:
  Updated call to init_sql_alloc().
  Mark memory used by temporary tables, that are not for slave threads, as MY_THREAD_SPECIFIC
  Updated call to init_sql_alloc()
sql/thr_malloc.cc:
  Added my_flags argument to init_sql_alloc() to be able to mark memory as MY_THREAD_SPECIFIC.
sql/thr_malloc.h:
  Updated prototype for init_sql_alloc()
sql/tztime.cc:
  Updated call to init_sql_alloc()
  Updated call to init_alloc_root() to mark memory thread specific.
  my_pthread_setspecific_ptr(THR_THD,...) -> set_current_thd()
sql/uniques.cc:
  Updated calls to init_tree(), my_init_dynamic_array() and my_malloc() to mark memory thread specific.
sql/unireg.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
storage/csv/ha_tina.cc:
  Updated call to init_alloc_root()
storage/federated/ha_federated.cc:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
  Ensure that memory allocated by fedarated is registered for the system, not for the thread.
storage/federatedx/federatedx_io_mysql.cc:
  Updated call to my_init_dynamic_array()
storage/federatedx/ha_federatedx.cc:
  Updated call to init_alloc_root()
  Updated call to my_init_dynamic_array()
storage/heap/ha_heap.cc:
  Added MY_THREAD_SPECIFIC to allocated memory.
storage/heap/heapdef.h:
  Added parameter to hp_get_new_block() to be able to do thread specific memory tagging.
storage/heap/hp_block.c:
  Added parameter to hp_get_new_block() to be able to do thread specific memory tagging.
storage/heap/hp_create.c:
  - Internal HEAP tables are now marking it's memory as MY_THREAD_SPECIFIC.
  - Use MY_TREE_WITH_DELETE instead of removed option 'with_delete'.
storage/heap/hp_open.c:
  Internal HEAP tables are now marking it's memory as MY_THREAD_SPECIFIC.
storage/heap/hp_write.c:
  Added new parameter to hp_get_new_block()
storage/maria/ma_bitmap.c:
  Updated call to my_init_dynamic_array()
storage/maria/ma_blockrec.c:
  Updated call to my_init_dynamic_array()
storage/maria/ma_check.c:
  Updated call to init_alloc_root()
storage/maria/ma_ft_boolean_search.c:
  Updated calls to init_tree() and init_alloc_root()
storage/maria/ma_ft_nlq_search.c:
  Updated call to init_tree()
storage/maria/ma_ft_parser.c:
  Updated call to init_tree()
  Updated call to init_alloc_root()
storage/maria/ma_loghandler.c:
  Updated call to my_init_dynamic_array()
storage/maria/ma_open.c:
  Updated call to my_init_dynamic_array()
storage/maria/ma_sort.c:
  Updated call to my_init_dynamic_array()
storage/maria/ma_write.c:
  Updated calls to my_init_dynamic_array() and init_tree()
storage/maria/maria_pack.c:
  Updated call to init_tree()
storage/maria/unittest/sequence_storage.c:
  Updated call to my_init_dynamic_array()
storage/myisam/ft_boolean_search.c:
  Updated call to init_tree()
  Updated call to init_alloc_root()
storage/myisam/ft_nlq_search.c:
  Updated call to init_tree()
storage/myisam/ft_parser.c:
  Updated call to init_tree()
  Updated call to init_alloc_root()
storage/myisam/ft_stopwords.c:
  Updated call to init_tree()
storage/myisam/mi_check.c:
  Updated call to init_alloc_root()
storage/myisam/mi_write.c:
  Updated call to my_init_dynamic_array()
  Updated call to init_tree()
storage/myisam/myisamlog.c:
  Updated call to init_tree()
storage/myisam/myisampack.c:
  Updated call to init_tree()
storage/myisam/sort.c:
  Updated call to my_init_dynamic_array()
storage/myisammrg/ha_myisammrg.cc:
  Updated call to init_sql_alloc()
storage/perfschema/pfs_check.cc:
  Rest current_thd
storage/perfschema/pfs_instr.cc:
  Removed DBUG_ENTER/DBUG_VOID_RETURN as at this point my_thread_var is not allocated anymore, which can cause problems.
support-files/compiler_warnings.supp:
  Disable compiler warning from offsetof macro.

1 files changed, 4 insertions, 4 deletions

diff --git a/mysys/my_fstream.c b/mysys/my_fstream.c
index e758609741b..de752fa149f 100644
--- a/mysys/my_fstream.c
+++ b/mysys/my_fstream.c
@@ -46,7 +46,7 @@ size_t my_fread(FILE *stream, uchar *Buffer, size_t Count, myf MyFlags)
 {
   size_t readbytes;
   DBUG_ENTER("my_fread");
-  DBUG_PRINT("my",("stream: 0x%lx  Buffer: 0x%lx  Count: %u  MyFlags: %d",
+  DBUG_PRINT("my",("stream: 0x%lx  Buffer: 0x%lx  Count: %u  MyFlags: %lu",
 		   (long) stream, (long) Buffer, (uint) Count, MyFlags));
 
   if ((readbytes= fread(Buffer, sizeof(char), Count, stream)) != Count)
@@ -94,7 +94,7 @@ size_t my_fwrite(FILE *stream, const uchar *Buffer, size_t Count, myf MyFlags)
   uint errors;
 #endif
   DBUG_ENTER("my_fwrite");
-  DBUG_PRINT("my",("stream: 0x%lx  Buffer: 0x%lx  Count: %u  MyFlags: %d",
+  DBUG_PRINT("my",("stream: 0x%lx  Buffer: 0x%lx  Count: %u  MyFlags: %lu",
 		   (long) stream, (long) Buffer, (uint) Count, MyFlags));
 
 #if !defined(NO_BACKGROUND) && defined(USE_MY_STREAM)
@@ -163,7 +163,7 @@ my_off_t my_fseek(FILE *stream, my_off_t pos, int whence,
 		  myf MyFlags __attribute__((unused)))
 {
   DBUG_ENTER("my_fseek");
-  DBUG_PRINT("my",("stream: 0x%lx  pos: %lu  whence: %d  MyFlags: %d",
+  DBUG_PRINT("my",("stream: 0x%lx  pos: %lu  whence: %d  MyFlags: %lu",
                    (long) stream, (long) pos, whence, MyFlags));
   DBUG_RETURN(fseek(stream, (off_t) pos, whence) ?
 	      MY_FILEPOS_ERROR : (my_off_t) ftell(stream));
@@ -176,7 +176,7 @@ my_off_t my_ftell(FILE *stream, myf MyFlags __attribute__((unused)))
 {
   off_t pos;
   DBUG_ENTER("my_ftell");
-  DBUG_PRINT("my",("stream: 0x%lx  MyFlags: %d", (long) stream, MyFlags));
+  DBUG_PRINT("my",("stream: 0x%lx  MyFlags: %lu", (long) stream, MyFlags));
   pos=ftell(stream);
   DBUG_PRINT("exit",("ftell: %lu",(ulong) pos));
   DBUG_RETURN((my_off_t) pos);