MDEV-7974 XA trnasactions.

XID_STATE::registered_for_binlog is replaced with rw_trans flag
in ha_prepare().

sql/handler.cc

@@ -113,6 +113,10 @@ TYPELIB tx_isolation_typelib= {array_elements(tx_isolation_names)-1,"",
 static TYPELIB known_extensions= {0,"known_exts", NULL, NULL};
 uint known_extensions_id= 0;
 
+static
+uint
+ha_check_and_coalesce_trx_read_only(THD *thd, Ha_trx_info *ha_list,
+                                    bool all);
 static int commit_one_phase_2(THD *thd, bool all, THD_TRANS *trans,
                               bool is_real_trans);
 
@@ -1247,7 +1251,6 @@ int ha_prepare(THD *thd)
   Ha_trx_info *ha_info= trans->ha_list;
   DBUG_ENTER("ha_prepare");
 
-  thd->transaction.xid_state.registered_for_binlog= false;
   if (ha_info)
   {
     for (; ha_info; ha_info= ha_info->next())
@@ -1272,8 +1275,12 @@ int ha_prepare(THD *thd)
       }
     }
 
-    if (thd->transaction.xid_state.registered_for_binlog &&
-        unlikely(tc_log->log_xa_prepare(thd, all)))
+    uint rw_ha_count=
+      ha_check_and_coalesce_trx_read_only(thd,trans->ha_list, all);
+    bool rw_trans=
+      (rw_ha_count > (thd->is_current_stmt_binlog_disabled()?0U:1U));
+
+    if (rw_trans && tc_log->log_xa_prepare(thd, all))
     {
       ha_rollback_trans(thd, all);
       error=1;

sql/log.cc

@@ -1958,12 +1958,11 @@ binlog_truncate_trx_cache(THD *thd, binlog_cache_mngr *cache_mngr, bool all)
 static int binlog_prepare(handlerton *hton, THD *thd, bool all)
 {
   /*
-    Mark the XA for binlogging.
-    Transactions with no binlog handler registered like readonly ones,
-    should not go to the binlog.
-    Real work is done in MYSQL_BIN_LOG::log_xa_prepare()
+    do nothing.
+    just pretend we can do 2pc, so that MySQL won't
+    switch to 1pc.
+    real work is done in MYSQL_BIN_LOG::log_xa_prepare()
   */
-  thd->transaction.xid_state.registered_for_binlog= true;
   return 0;
 }
 

sql/sql_class.h

@@ -1296,7 +1296,6 @@ typedef struct st_xid_state {
     That can cause inconsistencies (shoud be fixed?).
   */
   bool is_binlogged;
-  bool registered_for_binlog;
 
   /**
     Check that XA transaction has an uncommitted work. Report an error