Re: bzr commit into mysql-5.1 branch (aelkin:2656) Bug#36443, Bug#33029

[Andrei Elkin]

Mats,

> Hi Andrei,
>
> You still didn't make the copy assignment operator and the copy
> constructor private, which was the reason for replacing it with an
> explicit function instead.

That's my omission. Recommitting.

>
> I also find your definition of the swap operator quite strange, even
> though it is correct.
>
> You also introduced a number of member functions that were not needed
> and which violates the encapsuling.
>
> All I asked you to do is make the copy assignment operator and the copy
> constructor private and replace that with an explicit method.  I
> suggested that you implement a swap() operator instead of a
> shallow_copy(), since that avoid the problem with resource leaks.

But there is `swap' as you are confirming above, it's not instead.
Why can it be defined through copy_shallow()?


>
> I'll approve the patch, since it does not contain any obvious flaws, but
> I would advice you to make the two functions mentioned above private.
>

You mean the = op and the copy constructor, don't you?
It's been done.

cheers,

Andrei


> Just my few cents,
> Mats Kindahl
>
> Andrei Elkin wrote:
>> #At file:///home/andrei/MySQL/BZR/FIXES/bug36443-slave_crash_insert_trigger/
>> 
>>  2656 Andrei Elkin	2008-06-19
>>       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 that that was referred in out-of-declaration scope.
>>                         
>>       Fixed with correcting backing up and restoring scheme of
>>       auto_inc_intervals_forced, introduced by bug#33029, by means of shallow
> copying;
>>       added simulation code that forces executing those fixes of the former bug
> that
>>       targeted at master-and-slave having incompatible bug#33029-prone versions.
>> added:
>>   mysql-test/suite/bugs/r/rpl_bug33029.result
>>   mysql-test/suite/bugs/t/rpl_bug33029.test
>> modified:
>>   sql/slave.cc
>>   sql/sql_class.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/sql_class.cc
>>     swaps of backed and the actual auto_inc_intervals_forced basing on shallow
> coping.
>>   sql/structs.h
>>     Removing the deep _copy() and methods associated with it;
>>     adding methods to Discrete_intervals_list:
>>     
>>     private set_members();
>>     public  copy_shallow(), swap(), get_{head, tail, current}();
>>     empty_no_free() through set_members().
>> === 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	2008-06-19 14:04:11 +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	2008-06-19 14:04:11 +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	2008-06-19 14:04:11 +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/sql_class.cc'
>> --- a/sql/sql_class.cc	2008-05-20 07:38:17 +0000
>> +++ b/sql/sql_class.cc	2008-06-19 14:04:11 +0000
>> @@ -2882,8 +2882,8 @@ void THD::reset_sub_statement_state(Sub_
>>     */
>>    if (rpl_master_erroneous_autoinc(this))
>>    {
>> -    backup->auto_inc_intervals_forced= auto_inc_intervals_forced;
>> -    auto_inc_intervals_forced.empty();
>> +    DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
>> +    auto_inc_intervals_forced.swap(&backup->auto_inc_intervals_forced);
>>    }
>>  #endif
>>    
>> @@ -2931,8 +2931,8 @@ void THD::restore_sub_statement_state(Su
>>     */
>>    if (rpl_master_erroneous_autoinc(this))
>>    {
>> -    auto_inc_intervals_forced= backup->auto_inc_intervals_forced;
>> -    backup->auto_inc_intervals_forced.empty();
>> +    backup->auto_inc_intervals_forced.swap(&auto_inc_intervals_forced);
>> +    DBUG_ASSERT(backup->auto_inc_intervals_forced.nb_elements() == 0);
>>    }
>>  #endif
>>  
>> 
>> === modified file 'sql/structs.h'
>> --- a/sql/structs.h	2008-03-14 03:35:41 +0000
>> +++ b/sql/structs.h	2008-06-19 14:04:11 +0000
>> @@ -314,31 +314,20 @@ private:
>>    */
>>    Discrete_interval        *current;
>>    uint                  elements; // number of elements
>> -
>> -  /* helper function for copy construct and assignment operator */
>> -  void copy_(const Discrete_intervals_list& from)
>> -  {
>> -    for (Discrete_interval *i= from.head; i; i= i->next)
>> -    {
>> -      Discrete_interval j= *i;
>> -      append(&j);
>> -    }
>> +  void set_members(Discrete_interval *h, Discrete_interval *t,
>> +                   Discrete_interval *c, uint el)
>> +  {  
>> +    head= h;
>> +    tail= t;
>> +    current= c;
>> +    elements= el;
>>    }
>> +    
>>  public:
>>    Discrete_intervals_list() : head(NULL), current(NULL), elements(0) {};
>> -  Discrete_intervals_list(const Discrete_intervals_list& from)
>> -  {
>> -    copy_(from);
>> -  }
>> -  void operator=(const Discrete_intervals_list& from)
>> -  {
>> -    empty();
>> -    copy_(from);
>> -  }
>>    void empty_no_free()
>>    {
>> -    head= current= NULL;
>> -    elements= 0;
>> +    set_members(NULL, NULL, NULL, 0);
>>    }
>>    void empty()
>>    {
>> @@ -350,7 +339,24 @@ public:
>>      }
>>      empty_no_free();
>>    }
>> -
>> +  void copy_shallow(const Discrete_intervals_list * dli)
>> +  {
>> +    head= dli->get_head();
>> +    tail= dli->get_tail();
>> +    current= dli->get_current();
>> +    elements= dli->nb_elements();
>> +  }
>> +  void swap (Discrete_intervals_list * dli)
>> +  {
>> +    Discrete_interval *h, *t, *c;
>> +    uint el;
>> +    h= dli->get_head();
>> +    t= dli->get_tail();
>> +    c= dli->get_current();
>> +    el= dli->nb_elements();
>> +    dli->copy_shallow(this);
>> +    set_members(h, t, c, el);
>> +  }
>>    const Discrete_interval* get_next()
>>    {
>>      Discrete_interval *tmp= current;
>> @@ -364,4 +370,7 @@ public:
>>    ulonglong minimum()     const { return (head ? head->minimum() : 0); };
>>    ulonglong maximum()     const { return (head ? tail->maximum() : 0); };
>>    uint      nb_elements() const { return elements; }
>> +  Discrete_interval* get_head() const { return head; };
>> +  Discrete_interval* get_tail() const { return tail; };
>> +  Discrete_interval* get_current() const { return current; };
>>  };
>>