Backport of:

----------------------------------------------------------
revno: 2617.69.20
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-4284-1-assert
timestamp: Thu 2009-08-13 18:29:55 +0400
message:
  WL#4284 "Transactional DDL locking"
  A review fix.
  Since WL#4284 implementation separated MDL_request and MDL_ticket,
  MDL_request becamse a utility object necessary only to get a ticket.
  Store it by-value in TABLE_LIST with the intent to merge
  MDL_request::key with table_list->table_name and table_list->db
  in future.
  Change the MDL subsystem to not require MDL_requests to
  stay around till close_thread_tables().
  Remove the list of requests from the MDL context.
  Requests for shared metadata locks acquired in open_tables()
  are only used as a list in recover_from_failed_open_table_attempt(),
  which calls mdl_context.wait_for_locks() for this list.
  To keep such list for recover_from_failed_open_table_attempt(),
  introduce a context class (Open_table_context), that collects
  all requests.
  A lot of minor cleanups and simplications that became possible
  with this change.


sql/event_db_repository.cc:
  Remove alloc_mdl_requests(). Now MDL_request instance is a member
  of TABLE_LIST, and init_one_table() initializes it.
sql/ha_ndbcluster_binlog.cc:
  Remove now unnecessary declaration and initialization
  of binlog_mdl_request.
sql/lock.cc:
  No need to allocate MDL requests in lock_table_names() now.
sql/log.cc:
  Use init_one_table() method, remove alloc_mdl_requests(),
  which is now unnecessary.
sql/log_event.cc:
  No need to allocate mdl_request separately now.
  Use init_one_table() method.
sql/log_event_old.cc:
  Update to the new signature of close_tables_for_reopen().
sql/mdl.cc:
  Update try_acquire_exclusive_lock() to be more easy to use.
  Function lock_table_name_if_not_cached() has been removed.
  Make acquire_shared_lock() signature consistent with
  try_acquire_exclusive_lock() signature.
  Remove methods that are no longer used.
  Update comments.
sql/mdl.h:
  Implement an assignment operator that doesn't
  copy MDL_key (MDL_key::operator= is private and
  should remain private).
  This is a hack to work-around assignment of TABLE_LIST
  by value in several places. Such assignments violate
  encapsulation, since only perform a shallow copy.
  In most cases these assignments are a hack on their own.
sql/mysql_priv.h:
  Update signatures of close_thread_tables() and close_tables_for_reopen().
sql/sp.cc:
  Allocate TABLE_LIST in thd->mem_root.
  Use init_one_table().
sql/sp_head.cc:
  Use init_one_table().
  Remove thd->locked_tables_root, it's no longer needed.
sql/sql_acl.cc:
  Use init_mdl_requests() and init_one_table().
sql/sql_base.cc:
  Update to new signatures of try_acquire_shared_lock() and
  try_acquire_exclusive_lock().
  Remove lock_table_name_if_not_cached().
  Fix a bug in open_ltable() that would not return ER_LOCK_DEADLOCK
  in case of a failed lock_tables() and a multi-statement
  transaction.
  Fix a bug in open_and_lock_tables_derived() that would
  not return ER_LOCK_DEADLOCK in case of a multi-statement
  transaction and a failure of lock_tables().
  Move assignment of enum_open_table_action to a method of Open_table_context, a new class that maintains information
  for backoff actions.
  Minor rearrangements of the code.
  Remove alloc_mdl_requests() in functions that work with system
  tables: instead the patch ensures that callers always initialize
  TABLE_LIST argument.
sql/sql_class.cc:
  THD::locked_tables_root is no more.
sql/sql_class.h:
  THD::locked_tables_root is no more.
  Add a declaration for Open_table_context class.
sql/sql_delete.cc:
  Update to use the simplified MDL API.
sql/sql_handler.cc:
  TABLE_LIST::mdl_request is stored by-value now.
  Ensure that mdl_request.ticket is NULL for every request
  that is passed into MDL, to satisfy MDL asserts.
  @ sql/sql_help.cc
  Function open_system_tables_for_read() no longer initializes
  mdl_requests.
  Move TABLE_LIST::mdl_request initialization closer to
  TABLE_LIST initialization.
sql/sql_help.cc:
  Function open_system_tables_for_read() no longer initializes
  mdl_requests.
  Move TABLE_LIST::mdl_request initialization closer to
  TABLE_LIST initialization.
sql/sql_insert.cc:
  Remove assignment by-value of TABLE_LIST in
  TABLEOP_HOOKS. We can't carry over a granted
  MDL ticket from one table list to another.
sql/sql_parse.cc:
  Change alloc_mdl_requests() -> init_mdl_requests().
  @todo We can remove init_mdl_requests() altogether
  in some places: all places that call add_table_to_list()
  already have mdl requests initialized.
sql/sql_plugin.cc:
  Use init_one_table().
  THD::locked_tables_root is no more.
sql/sql_servers.cc:
  Use init_one_table().
sql/sql_show.cc:
  Update acquire_high_priority_shared_lock() to use
  TABLE_LIST::mdl_request rather than allocate an own.
  Fix get_trigger_table_impl() to use init_one_table(),
  check for out of memory, follow the coding style.
sql/sql_table.cc:
  Update to work with TABLE_LIST::mdl_request by-value.
  Remove lock_table_name_if_not_cached().
  The code that used to delegate to it is quite simple and
  concise without it now.
sql/sql_udf.cc:
  Use init_one_table().
sql/sql_update.cc:
  Update to use the new signature of close_tables_for_reopen().
sql/table.cc:
  Move re-setting of mdl_requests for prepared statements
  and stored procedures from close_thread_tables() to
  reinit_stmt_before_use().
  Change alloc_mdl_requests() to init_mdl_requests().
  init_mdl_requests() is a hack that can't be deleted
  until we don't have a list-aware TABLE_LIST constructor.
  Hopefully its use will be minimal
sql/table.h:
  Change alloc_mdl_requests() to init_mdl_requests()
  TABLE_LIST::mdl_request is stored by value.
sql/tztime.cc:
  We no longer initialize mdl requests in open_system_tables_for*()
  functions. Move this initialization closer to initialization
  of the rest of TABLE_LIST members.
storage/myisammrg/ha_myisammrg.cc:
  Simplify mdl_request initialization.

1 files changed, 9 insertions, 17 deletions

diff --git a/sql/sql_udf.cc b/sql/sql_udf.cc
index 7e557c3ce68..d27473c1959 100644
--- a/sql/sql_udf.cc
+++ b/sql/sql_udf.cc
@@ -138,11 +138,7 @@ void udf_init()
   lex_start(new_thd);
   new_thd->set_db(db, sizeof(db)-1);
 
-  bzero((uchar*) &tables,sizeof(tables));
-  tables.alias= tables.table_name= (char*) "func";
-  tables.lock_type = TL_READ;
-  tables.db= db;
-  alloc_mdl_requests(&tables, new_thd->mem_root);
+  tables.init_one_table(db, sizeof(db)-1, "func", 4, "func", TL_READ);
 
   if (simple_open_n_lock_tables(new_thd, &tables))
   {
@@ -483,10 +479,7 @@ int mysql_create_function(THD *thd,udf_func *udf)
 
   /* create entry in mysql.func table */
 
-  bzero((char*) &tables,sizeof(tables));
-  tables.db= (char*) "mysql";
-  tables.table_name= tables.alias= (char*) "func";
-  alloc_mdl_requests(&tables, thd->mem_root);
+  tables.init_one_table("mysql", 5, "func", 4, "func", TL_WRITE);
   /* Allow creation of functions even if we can't open func table */
   if (!(table = open_ltable(thd, &tables, TL_WRITE, 0)))
     goto err;
@@ -562,10 +555,8 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
   if (udf->dlhandle && !find_udf_dl(udf->dl))
     dlclose(udf->dlhandle);
 
-  bzero((char*) &tables,sizeof(tables));
-  tables.db=(char*) "mysql";
-  tables.table_name= tables.alias= (char*) "func";
-  alloc_mdl_requests(&tables, thd->mem_root);
+  tables.init_one_table("mysql", 5, "func", 4, "func", TL_WRITE);
+
   if (!(table = open_ltable(thd, &tables, TL_WRITE, 0)))
     goto err;
   table->use_all_columns();
@@ -579,15 +570,16 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
     if ((error = table->file->ha_delete_row(table->record[0])))
       table->file->print_error(error, MYF(0));
   }
-  close_thread_tables(thd);
-
   rw_unlock(&THR_LOCK_udf);
 
-  /* Binlog the drop function. */
+  /*
+    Binlog the drop function. Keep the table open and locked
+    while binlogging, to avoid binlog inconsistency.
+  */
   write_bin_log(thd, TRUE, thd->query(), thd->query_length());
 
   DBUG_RETURN(0);
- err:
+err:
   rw_unlock(&THR_LOCK_udf);
   DBUG_RETURN(1);
 }