Sven, hello.
Yesterday I did not recognize the problem, but this morning I
understood your point with great help of Kostja.
> Hi Andrei!
>
> I think there is a problem with this patch. It introduces a way for
> the assignment operator and the copy constructor to fail. The copy
> constructor is never used, but the assignment operator is used in one
> place in the server (namely, in sql_class.cc, at the top of
> THD::reset_sub_statement_state). This place does not check for the
> failure:
>
> if (rpl_master_erroneous_autoinc(this))
> {
> backup->auto_inc_intervals_forced= auto_inc_intervals_forced;
> auto_inc_intervals_forced.empty();
> }
yes, that's right.
>
> It looks as if it is actually not necessary to allocate more dynamic
> memory at this point. So I'd suggest to just copy the list pointers
> from auto_inc_intervals_forced to backup->auto_inc_intervals_forced,
> then call auto_inc_intervals_forces.empty_no_free(). Copy the list
> pointers should be done by a new member function.
agreed.
>
> After that, I think we can throw away the copy constructor and
> assignment operator, since they have the problem that they can fail
> (which is quite unexpected for an assignment) and since they are not
> used any more.
I removed unused _copy() and the copy constructor.
>
>
> Andrei Elkin wrote:
>> #At file:///home/andrei/MySQL/BZR/FIXES/bug36443-slave_crash_insert_trigger/
>>
>> 2656 Andrei Elkin 2008-06-17
>> Bug #36443 Server crashes when executing insert when insert trigger on
> table
>> The crash appeared to be a result of allocating an
>> instance of Discrete_interval automatically whereas it meant
>> to be dynamical.
>> Fixed with correcting the allocation introduced by
>> bug@33029;
>> added simulation code that forces executing those fixes of bug@33029 that
> targeted
>> at master-and-slave having incompatible bug33029-prone versions.
>> added:
>> mysql-test/suite/bugs/r/rpl_bug33029.result
>> mysql-test/suite/bugs/t/rpl_bug33029.test
>> modified:
>> sql/slave.cc
>> sql/structs.h
>>
>> per-file messages:
>> mysql-test/suite/bugs/r/rpl_bug33029.result
>> new results file
>> mysql-test/suite/bugs/t/rpl_bug33029.test
>> test merely checks no crash happens on slave.
>> sql/slave.cc
>> forcing to execute special logics implemented for bug#33029 if
>> simulate_bug33029 the debug option is set.
>> sql/structs.h
>> converting automatic allocation of a being appended item to Discrete_interval
> to dynamic.
>> === added file 'mysql-test/suite/bugs/r/rpl_bug33029.result'
>> --- a/mysql-test/suite/bugs/r/rpl_bug33029.result 1970-01-01 00:00:00 +0000
>> +++ b/mysql-test/suite/bugs/r/rpl_bug33029.result 2008-06-17 15:32:36 +0000
>> @@ -0,0 +1,15 @@
>> +stop slave;
>> +drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
>> +reset master;
>> +reset slave;
>> +drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
>> +start slave;
>> +create table `t1` (`id` int not null auto_increment primary key);
>> +create trigger `trg` before insert on `t1` for each row begin end;
>> +set @@global.debug="+d,simulate_bug33029";
>> +stop slave;
>> +start slave;
>> +insert into `t1` values ();
>> +select * from t1;
>> +id
>> +1
>>
>> === added file 'mysql-test/suite/bugs/t/rpl_bug33029.test'
>> --- a/mysql-test/suite/bugs/t/rpl_bug33029.test 1970-01-01 00:00:00 +0000
>> +++ b/mysql-test/suite/bugs/t/rpl_bug33029.test 2008-06-17 15:32:36 +0000
>> @@ -0,0 +1,25 @@
>> +#
>> +# Bug #36443 Server crashes when executing insert when insert trigger on table
>> +#
>> +# Emulating the former bug#33029 situation to see that there is no crash
> anymore.
>> +# +
>> +
>> +source include/master-slave.inc;
>> +
>> +create table `t1` (`id` int not null auto_increment primary key);
>> +create trigger `trg` before insert on `t1` for each row begin end;
>> +
>> +sync_slave_with_master;
>> +set @@global.debug="+d,simulate_bug33029";
>> +
>> +stop slave;
>> +start slave;
>> +
>> +connection master;
>> +
>> +insert into `t1` values ();
>> +
>> +sync_slave_with_master;
>> +select * from t1;
>> +
>>
>> === modified file 'sql/slave.cc'
>> --- a/sql/slave.cc 2008-03-31 08:57:18 +0000
>> +++ b/sql/slave.cc 2008-06-17 15:32:36 +0000
>> @@ -4136,6 +4136,7 @@ bool rpl_master_erroneous_autoinc(THD *t
>> if (active_mi && active_mi->rli.sql_thd == thd)
>> {
>> Relay_log_info *rli= &active_mi->rli;
>> + DBUG_EXECUTE_IF("simulate_bug33029", return TRUE;);
>> return rpl_master_has_bug(rli, 33029, FALSE);
>> }
>> return FALSE;
>>
>> === modified file 'sql/structs.h'
>> --- a/sql/structs.h 2008-03-14 03:35:41 +0000
>> +++ b/sql/structs.h 2008-06-17 15:32:36 +0000
>> @@ -315,13 +315,24 @@ private:
>> Discrete_interval *current;
>> uint elements; // number of elements
>> - /* helper function for copy construct and assignment operator */
>> + /* + helper function for copy construct and assignment
>> operator
>> + @note if dynamic allocation fails the target list is nullified
>> + */
>> void copy_(const Discrete_intervals_list& from)
>> {
>> for (Discrete_interval *i= from.head; i; i= i->next)
>> {
>> - Discrete_interval j= *i;
>> - append(&j);
>> + Discrete_interval *j= new Discrete_interval(*i);
>> + if (j == NULL)
>> + {
>> + empty();
>> + break;
>> + }
>> + else
>> + {
>> + append(j);
>> + }
>> }
>> }
>> public:
>>
>>
A new patch has been committed.
cheers,
Andrei
