1. 07 Mar, 2007 3 commits
    • kostja@bodhi.local's avatar
      Merge bodhi.local:/opt/local/work/mysql-5.0-26750 · ae978961
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.1-runtime
      ae978961
    • kostja@bodhi.local's avatar
      Merge bk-internal.mysql.com:/home/bk/mysql-5.0-runtime · c2e0e5af
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.0-26750
      c2e0e5af
    • kostja@bodhi.local's avatar
      A fix for Bug#26750 "valgrind leak in sp_head" (and post-review · 86f02cd3
      kostja@bodhi.local authored
      fixes).
      
      The legend: on a replication slave, in case a trigger creation
      was filtered out because of application of replicate-do-table/
      replicate-ignore-table rule, the parsed definition of a trigger was not 
      cleaned up properly. LEX::sphead member was left around and leaked 
      memory. Until the actual implementation of support of 
      replicate-ignore-table rules for triggers by the patch for Bug 24478 it 
      was never the case that "case SQLCOM_CREATE_TRIGGER"
      was not executed once a trigger was parsed,
      so the deletion of lex->sphead there worked and the memory did not leak.
      
      The fix: 
      
      The real cause of the bug is that there is no 1 or 2 places where
      we can clean up the main LEX after parse. And the reason we 
      can not have just one or two places where we clean up the LEX is
      asymmetric behaviour of MYSQLparse in case of success or error. 
      
      One of the root causes of this behaviour is the code in Item::Item()
      constructor. There, a newly created item adds itself to THD::free_list
      - a single-linked list of Items used in a statement. Yuck. This code
      is unaware that we may have more than one statement active at a time,
      and always assumes that the free_list of the current statement is
      located in THD::free_list. One day we need to be able to explicitly
      allocate an item in a given Query_arena.
      Thus, when parsing a definition of a stored procedure, like
      CREATE PROCEDURE p1() BEGIN SELECT a FROM t1; SELECT b FROM t1; END;
      we actually need to reset THD::mem_root, THD::free_list and THD::lex
      to parse the nested procedure statement (SELECT *).
      The actual reset and restore is implemented in semantic actions
      attached to sp_proc_stmt grammar rule.
      The problem is that in case of a parsing error inside a nested statement
      Bison generated parser would abort immediately, without executing the
      restore part of the semantic action. This would leave THD in an 
      in-the-middle-of-parsing state.
      This is why we couldn't have had a single place where we clean up the LEX
      after MYSQLparse - in case of an error we needed to do a clean up
      immediately, in case of success a clean up could have been delayed.
      This left the door open for a memory leak.
      
      One of the following possibilities were considered when working on a fix:
      - patch the replication logic to do the clean up. Rejected
      as breaks module borders, replication code should not need to know the
      gory details of clean up procedure after CREATE TRIGGER.
      - wrap MYSQLparse with a function that would do a clean up.
      Rejected as ideally we should fix the problem when it happens, not
      adjust for it outside of the problematic code.
      - make sure MYSQLparse cleans up after itself by invoking the clean up
      functionality in the appropriate places before return. Implemented in 
      this patch.
      - use %destructor rule for sp_proc_stmt to restore THD - cleaner
      than the prevoius approach, but rejected
      because needs a careful analysis of the side effects, and this patch is 
      for 5.0, and long term we need to use the next alternative anyway
      - make sure that sp_proc_stmt doesn't juggle with THD - this is a 
      large work that will affect many modules.
      
      Cleanup: move main_lex and main_mem_root from Statement to its
      only two descendants Prepared_statement and THD. This ensures that
      when a Statement instance was created for purposes of statement backup,
      we do not involve LEX constructor/destructor, which is fairly expensive.
      In order to track that the transformation produces equivalent 
      functionality please check the respective constructors and destructors
      of Statement, Prepared_statement and THD - these members were
      used only there.
      This cleanup is unrelated to the patch.
      86f02cd3
  2. 06 Mar, 2007 9 commits
    • malff/marcsql@weblab.(none)'s avatar
      Manual merge · 82c1c023
      malff/marcsql@weblab.(none) authored
      82c1c023
    • malff/marcsql@weblab.(none)'s avatar
      Merge malff@bk-internal.mysql.com:/home/bk/mysql-5.1-runtime · e648fb17
      malff/marcsql@weblab.(none) authored
      into  weblab.(none):/home/marcsql/TREE/mysql-5.1-8407-merge
      e648fb17
    • malff/marcsql@weblab.(none)'s avatar
      Manual merge · fedd1ae7
      malff/marcsql@weblab.(none) authored
      fedd1ae7
    • kostja@bodhi.local's avatar
      Post-merge fixes. · d0cc0355
      kostja@bodhi.local authored
      d0cc0355
    • malff/marcsql@weblab.(none)'s avatar
      Merge malff@bk-internal.mysql.com:/home/bk/mysql-5.0-runtime · 9f0b0df9
      malff/marcsql@weblab.(none) authored
      into  weblab.(none):/home/marcsql/TREE/mysql-5.0-8407_b
      9f0b0df9
    • malff/marcsql@weblab.(none)'s avatar
      Merge weblab.(none):/home/marcsql/TREE/mysql-5.0-8407_b · 8643745d
      malff/marcsql@weblab.(none) authored
      into  weblab.(none):/home/marcsql/TREE/mysql-5.1-8407-merge
      8643745d
    • kostja@bodhi.local's avatar
      Merge bodhi.local:/opt/local/work/mysql-5.0-runtime · 92b44016
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.1-runtime-merge
      92b44016
    • kostja@bodhi.local's avatar
      Merge bk-internal.mysql.com:/home/bk/mysql-5.1-new-rpl · 3d488d49
      kostja@bodhi.local authored
      into  bodhi.local:/opt/local/work/mysql-5.1-runtime-merge
      3d488d49
    • malff/marcsql@weblab.(none)'s avatar
      Bug#8407 (Stored functions/triggers ignore exception handler) · b216d959
      malff/marcsql@weblab.(none) authored
      Bug 18914 (Calling certain SPs from triggers fail)
      Bug 20713 (Functions will not not continue for SQLSTATE VALUE '42S02')
      Bug 21825 (Incorrect message error deleting records in a table with a
        trigger for inserting)
      Bug 22580 (DROP TABLE in nested stored procedure causes strange dependency
        error)
      Bug 25345 (Cursors from Functions)
      
      
      This fix resolves a long standing issue originally reported with bug 8407,
      which affect the behavior of Stored Procedures, Stored Functions and Trigger
      in many different ways, causing symptoms reported by all the bugs listed.
      In all cases, the root cause of the problem traces back to 8407 and how the
      server locks tables involved with sub statements.
      
      Prior to this fix, the implementation of stored routines would:
      - compute the transitive closure of all the tables referenced by a top level
      statement
      - open and lock all the tables involved
      - execute the top level statement
      "transitive closure of tables" means collecting:
      - all the tables,
      - all the stored functions,
      - all the views,
      - all the table triggers
      - all the stored procedures
      involved, and recursively inspect these objects definition to find more
      references to more objects, until the list of every object referenced does
      not grow any more.
      This mechanism is known as "pre-locking" tables before execution.
      The motivation for locking all the tables (possibly) used at once is to
      prevent dead locks.
      
      One problem with this approach is that, if the execution path the code
      really takes during runtime does not use a given table, and if the table is
      missing, the server would not execute the statement.
      This in particular has a major impact on triggers, since a missing table
      referenced by an update/delete trigger would prevent an insert trigger to run.
      
      Another problem is that stored routines might define SQL exception handlers
      to deal with missing tables, but the server implementation would never give
      user code a chance to execute this logic, since the routine is never
      executed when a missing table cause the pre-locking code to fail.
      
      With this fix, the internal implementation of the pre-locking code has been
      relaxed of some constraints, so that failure to open a table does not
      necessarily prevent execution of a stored routine.
      
      In particular, the pre-locking mechanism is now behaving as follows:
      
      1) the first step, to compute the transitive closure of all the tables
      possibly referenced by a statement, is unchanged.
      
      2) the next step, which is to open all the tables involved, only attempts
      to open the tables added by the pre-locking code, but silently fails without
      reporting any error or invoking any exception handler is the table is not
      present. This is achieved by trapping internal errors with
      Prelock_error_handler
      
      3) the locking step only locks tables that were successfully opened.
      
      4) when executing sub statements, the list of tables used by each statements
      is evaluated as before. The tables needed by the sub statement are expected
      to be already opened and locked. Statement referencing tables that were not
      opened in step 2) will fail to find the table in the open list, and only at
      this point will execution of the user code fail.
      
      5) when a runtime exception is raised at 4), the instruction continuation
      destination (the next instruction to execute in case of SQL continue
      handlers) is evaluated.
      This is achieved with sp_instr::exec_open_and_lock_tables()
      
      6) if a user exception handler is present in the stored routine, that
      handler is invoked as usual, so that ER_NO_SUCH_TABLE exceptions can be
      trapped by stored routines. If no handler exists, then the runtime execution
      will fail as expected.
      
      With all these changes, a side effect is that view security is impacted, in
      two different ways.
      
      First, a view defined as "select stored_function()", where the stored
      function references a table that may not exist, is considered valid.
      The rationale is that, because the stored function might trap exceptions
      during execution and still return a valid result, there is no way to decide
      when the view is created if a missing table really cause the view to be invalid.
      
      Secondly, testing for existence of tables is now done later during
      execution. View security, which consist of trapping errors and return a
      generic ER_VIEW_INVALID (to prevent disclosing information) was only
      implemented at very specific phases covering *opening* tables, but not
      covering the runtime execution. Because of this existing limitation,
      errors that were previously trapped and converted into ER_VIEW_INVALID are
      not trapped, causing table names to be reported to the user.
      This change is exposing an existing problem, which is independent and will
      be resolved separately.
      b216d959
  3. 05 Mar, 2007 1 commit
  4. 02 Mar, 2007 9 commits
  5. 01 Mar, 2007 18 commits