Better approach for prelocking of tables for stored routines execution

and some SP-related cleanups.

- We don't have separate stage for calculation of list of tables
  to be prelocked and doing implicit LOCK/UNLOCK any more.
  Instead we calculate this list at open_tables() and do implicit
  LOCK in lock_tables() (and UNLOCK in close_thread_tables()).
  Also now we support cases when same table (with same alias) is
  used several times in the same query in SP.

- Cleaned up execution of SP. Moved all common code which handles
  LEX and does preparations before statement execution or complex
  expression evaluation to auxilary sp_lex_keeper class. Now 
  all statements in SP (and corresponding instructions) that
  evaluate expression which can contain subquery have their
  own LEX.

1 files changed, 4 insertions, 4 deletions

diff --git a/sql/sp_rcontext.cc b/sql/sp_rcontext.cc
index 0c6c8c5aa70..a2e2a38dfff 100644
--- a/sql/sp_rcontext.cc
+++ b/sql/sp_rcontext.cc
@@ -125,9 +125,9 @@ sp_rcontext::restore_variables(uint fp)
 }
 
 void
-sp_rcontext::push_cursor(LEX *lex)
+sp_rcontext::push_cursor(sp_lex_keeper *lex_keeper)
 {
-  m_cstack[m_ccount++]= new sp_cursor(lex);
+  m_cstack[m_ccount++]= new sp_cursor(lex_keeper);
 }
 
 void
@@ -148,7 +148,7 @@ sp_rcontext::pop_cursors(uint count)
 
 // We have split this in two to make it easy for sp_instr_copen
 // to reuse the sp_instr::exec_stmt() code.
-LEX *
+sp_lex_keeper*
 sp_cursor::pre_open(THD *thd)
 {
   if (m_isopen)
@@ -168,7 +168,7 @@ sp_cursor::pre_open(THD *thd)
 
   m_nseof= thd->net.no_send_eof;
   thd->net.no_send_eof= TRUE;
-  return m_lex;
+  return m_lex_keeper;
 }
 
 void