Moved normal transaction xid to implicit_xid

Part of MDEV-7974 - backport fix for mysql bug#12161 (XA and binlog)

sql/handler.cc

@@ -1199,8 +1199,11 @@ void trans_register_ha(THD *thd, bool all, handlerton *ht_arg)
   ha_info->register_ha(trans, ht_arg);
 
   trans->no_2pc|=(ht_arg->prepare==0);
-  if (thd->transaction.xid_state.xid.is_null())
-    thd->transaction.xid_state.xid.set(thd->query_id);
+
+  /* Set implicit xid even if there's explicit XA, it will be ignored anyway. */
+  if (thd->transaction.implicit_xid.is_null())
+    thd->transaction.implicit_xid.set(thd->query_id);
+
   DBUG_VOID_RETURN;
 }
 
@@ -1541,7 +1544,10 @@ int ha_commit_trans(THD *thd, bool all)
 
   need_prepare_ordered= FALSE;
   need_commit_ordered= FALSE;
-  xid= thd->transaction.xid_state.xid.get_my_xid();
+  DBUG_ASSERT(thd->transaction.implicit_xid.get_my_xid() ==
+              thd->transaction.implicit_xid.quick_get_my_xid());
+  xid= thd->transaction.xid_state.is_explicit_XA() ? 0 :
+       thd->transaction.implicit_xid.quick_get_my_xid();
 
   for (Ha_trx_info *hi= ha_info; hi; hi= hi->next())
   {

sql/session_tracker.cc

@@ -1285,7 +1285,7 @@ bool Transaction_state_tracker::store(THD *thd, String *buf)
 
       if ((tx_curr_state & TX_EXPLICIT) && is_xa)
       {
-        XID *xid= &thd->transaction.xid_state.xid;
+        XID *xid= thd->transaction.xid_state.get_xid();
         long glen, blen;
 
         buf->append(STRING_WITH_LEN("XA START"));

sql/sql_class.cc

@@ -1159,10 +1159,12 @@ void thd_get_xid(const MYSQL_THD thd, MYSQL_XID *xid)
   if (!thd->wsrep_xid.is_null())
   {
     *xid = *(MYSQL_XID *) &thd->wsrep_xid;
+    return;
   }
-  else
 #endif /* WITH_WSREP */
-  *xid = *(MYSQL_XID *) &thd->transaction.xid_state.xid;
+  *xid= thd->transaction.xid_state.is_explicit_XA() ?
+        *(MYSQL_XID *) thd->transaction.xid_state.get_xid() :
+        *(MYSQL_XID *) &thd->transaction.implicit_xid;
 }
 
 
@@ -1386,7 +1388,7 @@ void THD::init_for_queries()
                       variables.trans_alloc_block_size,
                       variables.trans_prealloc_size);
   DBUG_ASSERT(!transaction.xid_state.is_explicit_XA());
-  DBUG_ASSERT(transaction.xid_state.xid.is_null());
+  DBUG_ASSERT(transaction.implicit_xid.is_null());
 }
 
 

sql/sql_class.h

@@ -2582,6 +2582,7 @@ class THD: public THD_count, /* this must be first */
     THD_TRANS stmt;			// Trans for current statement
     bool on;                            // see ha_enable_transaction()
     XID_STATE xid_state;
+    XID implicit_xid;
     WT_THD wt;                          ///< for deadlock detection
     Rows_log_event *m_pending_rows_event;
 
@@ -2606,9 +2607,7 @@ class THD: public THD_count, /* this must be first */
       DBUG_ENTER("THD::st_transactions::cleanup");
       changed_tables= 0;
       savepoints= 0;
-      /* xid_cache_delete() resets xid of explicitly started XA transaction */
-      if (!xid_state.is_explicit_XA())
-        xid_state.xid.null();
+      implicit_xid.null();
       free_root(&mem_root,MYF(MY_KEEP_PREALLOC));
       DBUG_VOID_RETURN;
     }
@@ -2620,6 +2619,7 @@ class THD: public THD_count, /* this must be first */
     {
       bzero((char*)this, sizeof(*this));
       xid_state.xid.null();
+      implicit_xid.null();
       init_sql_alloc(&mem_root, "THD::transactions",
                      ALLOC_ROOT_MIN_BLOCK_SIZE, 0,
                      MYF(MY_THREAD_SPECIFIC));

sql/wsrep_applier.cc

@@ -184,12 +184,6 @@ int wsrep_apply_events(THD*        thd,
     thd->set_server_id(ev->server_id);
     thd->set_time();                            // time the query
     thd->transaction.start_time.reset(thd);
-    //#define mariadb_10_4_0
-#ifdef mariadb_10_4_0
-    wsrep_xid_init(&thd->transaction.xid_state.xid,
-                   thd->wsrep_trx_meta.gtid.uuid,
-                   thd->wsrep_trx_meta.gtid.seqno);
-#endif
     thd->lex->current_select= 0;
     if (!ev->when)
     {

sql/xa.cc

@@ -188,6 +188,13 @@ bool XID_STATE::check_has_uncommitted_xa() const
 }
 
 
+XID *XID_STATE::get_xid() const
+{
+  DBUG_ASSERT(is_explicit_XA());
+  return const_cast<XID*>(&xid);
+}
+
+
 void xid_cache_init()
 {
   xid_cache_inited= true;

sql/xa.h

@@ -28,6 +28,7 @@ struct XID_STATE {
   bool is_explicit_XA() const { return xid_cache_element != 0; }
   void set_error(uint error);
   void er_xaer_rmfail() const;
+  XID *get_xid() const;
 };
 
 void xid_cache_init(void);