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MDEV-37602: Phase 1 & 2 - Session-scoped rgi and Master_info registration in index #5159

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MDEV-37602: Phase 1 & 2 - Session-scoped rgi and Master_info registration in index #5159

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90 changes: 47 additions & 43 deletions sql/sql_binlog.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include "rpl_mi.h"
#include "slave.h"
#include "log_event.h"
#include <cstdio>


/**
Expand Down Expand Up @@ -163,14 +164,7 @@ int save_restore_context_apply_event(Log_event *ev, rpl_group_info *rgi)

THD *thd= rgi->thd;
Relay_log_info *rli= thd->rli_fake;
DBUG_ASSERT(!rli->mi);
LEX_CSTRING connection_name= { STRING_WITH_LEN("BINLOG_BASE64_EVENT") };

if (!(rli->mi= new Master_info(&connection_name, false)))
{
my_error(ER_OUT_OF_RESOURCES, MYF(0));
return -1;
}
DBUG_ASSERT(rli->mi);

sql_digest_state *m_digest= thd->m_digest;
PSI_statement_locker *m_statement_psi= thd->m_statement_psi;;
Expand All @@ -189,8 +183,6 @@ int save_restore_context_apply_event(Log_event *ev, rpl_group_info *rgi)
thd->m_statement_psi= m_statement_psi;
thd->variables.pseudo_thread_id= m_thread_id;
thd->reset_db(&save_db);
delete rli->mi;
rli->mi= NULL;

return err;
}
Expand Down Expand Up @@ -234,28 +226,55 @@ void mysql_client_binlog_statement(THD* thd)

int err;
Relay_log_info *rli;
rpl_group_info *rgi;
rpl_group_info *rgi= thd->rgi_fake;
uchar *buf= NULL;
size_t coded_len= 0, decoded_len= 0;

rli= thd->rli_fake;
if (!rli && (rli= thd->rli_fake= new Relay_log_info(FALSE, "BINLOG_BASE64_EVENT")))
rli->sql_driver_thd= thd;
if (!(rgi= thd->rgi_fake))
rgi= thd->rgi_fake= new rpl_group_info(rli);
rgi->thd= thd;
const char *error= 0;
Log_event *ev = 0;
Log_event *ev= 0;
my_bool is_fragmented= FALSE;
my_bool keep_rgi= false;
/*
Out of memory check
*/
if (!(rli))

rli= thd->rli_fake;
if (!rli)
{
my_error(ER_OUTOFMEMORY, MYF(ME_FATAL), 1); /* needed 1 bytes */
goto end;
/*
Create a session-scoped Master_info. Its embedded Relay_log_info
serves as rli_fake for the connection, eliminating throwaway
Master_info creation per Query event in save_restore_context_apply_event().
Register it in master_info_index for visibility in SHOW SLAVE STATUS.
*/
char conn_name_buf[64];
int len= snprintf(conn_name_buf, sizeof(conn_name_buf),
"binlog_replay_%llu",
(unsigned long long)thd->thread_id);
LEX_CSTRING connection_name= { conn_name_buf, (size_t)len };

Master_info *mi= new Master_info(&connection_name, false);
if (!mi || mi->error())
{
delete mi;
my_error(ER_OUTOFMEMORY, MYF(ME_FATAL), 1);
goto end;
}
mi->rli.mi= mi;
mi->rli.sql_driver_thd= thd;

/*
Register in master_info_index so it appears in monitoring queries.
Pass write_to_file=FALSE since binlog_replay connections are ephemeral.
*/
if (master_info_index->add_master_info(mi, FALSE))
{
delete mi;
my_error(ER_OUTOFMEMORY, MYF(ME_FATAL), 1);
goto end;
}
Comment on lines +265 to +270
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@gemini-code-assist gemini-code-assist Bot Jun 1, 2026

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critical

The global master_info_index can be NULL on standalone servers where replication is not initialized or disabled. Dereferencing it directly will cause a server crash when executing BINLOG statements. Additionally, modifying master_info_index requires holding the LOCK_active_mi mutex to prevent race conditions with other threads (e.g., concurrent SHOW STATUS or administrative commands).

Please add a NULL check for master_info_index and wrap the registration in LOCK_active_mi.

    if (master_info_index)
    {
      mysql_mutex_lock(&LOCK_active_mi);
      if (master_info_index->add_master_info(mi, FALSE))
      {
        mysql_mutex_unlock(&LOCK_active_mi);
        delete mi;
        my_error(ER_OUTOFMEMORY, MYF(ME_FATAL), 1);
        goto end;
      }
      mysql_mutex_unlock(&LOCK_active_mi);
    }


thd->mi_fake= mi;
thd->rli_fake= rli= &mi->rli;
}
if (!rgi)
rgi= thd->rgi_fake= new rpl_group_info(rli);
rgi->thd= thd;
Comment on lines +275 to +277
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@gemini-code-assist gemini-code-assist Bot Jun 1, 2026

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medium

If new rpl_group_info(rli) fails and returns NULL due to an out-of-memory condition, dereferencing rgi on the next line (rgi->thd = thd;) will cause a server crash. We should check if rgi is NULL and handle the error gracefully.

  if (!rgi)
  {
    if (!(rgi= thd->rgi_fake= new rpl_group_info(rli)))
    {
      my_error(ER_OUTOFMEMORY, MYF(ME_FATAL), 1);
      goto end;
    }
  }
  rgi->thd= thd;


DBUG_ASSERT(rli->belongs_to_client());

Expand Down Expand Up @@ -412,16 +431,6 @@ void mysql_client_binlog_statement(THD* thd)
*/
LEX *backup_lex;

/*
If we are re-assembling a Rows_log_event from a group of
Partial_rows_log_events, the rgi houses the assembler, so we need
it around while we are re-constructing the event.
*/
if (ev->get_type_code() == PARTIAL_ROW_DATA_EVENT &&
(((Partial_rows_log_event *) ev)->seq_no <
((Partial_rows_log_event *) ev)->total_fragments))
keep_rgi= true;

thd->backup_and_reset_current_lex(&backup_lex);
err= save_restore_context_apply_event(ev, rgi);
thd->restore_current_lex(backup_lex);
Expand Down Expand Up @@ -462,13 +471,8 @@ void mysql_client_binlog_statement(THD* thd)
if (unlikely(is_fragmented))
my_free(const_cast<char*>(thd->lex->comment.str));
thd->variables.option_bits= thd_options;
rgi->slave_close_thread_tables(thd);
if (rgi)
rgi->slave_close_thread_tables(thd);
my_free(buf);

if (!keep_rgi)
{
delete rgi;
rgi= thd->rgi_fake= NULL;
}
DBUG_VOID_RETURN;
}
28 changes: 25 additions & 3 deletions sql/sql_class.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
#include "sql_base.h"
#include "sql_handler.h" // mysql_ha_cleanup
#include "rpl_rli.h"
#include "rpl_mi.h"
#include "rpl_filter.h"
#include "rpl_record.h"
#include "slave.h"
Expand Down Expand Up @@ -714,7 +715,7 @@ const char *thd_where(THD *thd)
THD::THD(my_thread_id id, bool is_wsrep_applier)
:Statement(&main_lex, &main_mem_root, STMT_CONVENTIONAL_EXECUTION,
/* statement id */ 0),
rli_fake(0), rgi_fake(0), rgi_slave(NULL),
mi_fake(0), rli_fake(0), rgi_fake(0), rgi_slave(NULL),
protocol_text(this), protocol_binary(this), initial_status_var(0),
m_current_stage_key(0), m_psi(0), start_time(0), start_time_sec_part(0),
in_sub_stmt(0), log_all_errors(0),
Expand Down Expand Up @@ -1792,8 +1793,29 @@ void THD::free_connection()
net_end(&net);
delete(rgi_fake);
rgi_fake= NULL;
delete(rli_fake);
rli_fake= NULL;
if (mi_fake)
{
/*
When mi_fake is set, it's a session-scoped Master_info for BINLOG replay.
Deregister it from master_info_index before deleting.
The rli_fake points to the embedded Relay_log_info inside Master_info.
Deleting mi_fake destroys the RLI along with it.
*/
if (master_info_index)
{
mysql_mutex_lock(&LOCK_active_mi);
master_info_index->remove_master_info(mi_fake, FALSE);
mysql_mutex_unlock(&LOCK_active_mi);
}
delete mi_fake;
mi_fake= NULL;
rli_fake= NULL;
}
else
{
delete(rli_fake);
rli_fake= NULL;
}
#endif
if (!cleanup_done)
cleanup();
Expand Down
2 changes: 2 additions & 0 deletions sql/sql_class.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,7 @@ enum wsrep_consistency_check_mode {

class Reprepare_observer;
class Relay_log_info;
class Master_info;
struct rpl_group_info;
struct rpl_parallel_thread;
class Rpl_filter;
Expand Down Expand Up @@ -3195,6 +3196,7 @@ class THD: public THD_count, /* this must be first */
MDL_context mdl_context;

/* Used to execute base64 coded binlog events in MySQL server */
Master_info* mi_fake;
Relay_log_info* rli_fake;
rpl_group_info* rgi_fake;
/* Slave applier execution context */
Expand Down
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