MDEV-18983 WIP 2

Author: ParadoxV5

mysql-test/main/mysqld--help.result

@@ -1282,9 +1282,14 @@ The following specify which files/extra groups are read (specified before remain
  replication in the master
  --rpl-semi-sync-master-trace-level=# 
  The tracing level for semi-sync replication
+ --rpl-semi-sync-master-wait-for-slave-count=# 
+ The number of slaves that need to acknowledge that they
+ have received a transaction before the transaction can
+ complete on the master
  --rpl-semi-sync-master-wait-no-slave 
- Wait until timeout when no semi-synchronous replication
- slave is available
+ Wait until timeout when less than
+ `rpl_semi_sync_master_wait_for_slave_count`
+ semi-synchronous replication slaves are available
  (Defaults to on; use --skip-rpl-semi-sync-master-wait-no-slave to disable.)
  --rpl-semi-sync-master-wait-point=name 
  Should transaction wait for semi-sync ack after having
@@ -1991,6 +1996,7 @@ rowid-merge-buff-size 8388608
 rpl-semi-sync-master-enabled FALSE
 rpl-semi-sync-master-timeout 10000
 rpl-semi-sync-master-trace-level 32
+rpl-semi-sync-master-wait-for-slave-count 1
 rpl-semi-sync-master-wait-no-slave TRUE
 rpl-semi-sync-master-wait-point AFTER_COMMIT
 rpl-semi-sync-slave-delay-master FALSE

sql/semisync_master.cc

@@ -679,17 +679,14 @@ int Repl_semi_sync_master::report_reply_binlog(uint32 server_id,
 
   if (need_copy_send_pos)
   {
-    DBUG_ASSERT(m_active_tranxs);
-    Tranx_node *entry=
-      m_active_tranxs->get_tranx_node(log_file_name, log_file_pos);
-    DBUG_ASSERT(entry);
+    Tranx_node *entry;
+    strmake_buf(m_reply_file_name, log_file_name);
+    m_reply_file_pos = log_file_pos;
+    m_reply_file_name_inited = true;
 
-    if (++(entry->acks) >= rpl_semi_sync_master_wait_for_slave_count)
+    entry= m_active_tranxs->get_tranx_node(log_file_name, log_file_pos);
+    if (entry && ++(entry->acks) >= rpl_semi_sync_master_wait_for_slave_count)
     {
-      strmake_buf(m_reply_file_name, log_file_name);
-      m_reply_file_pos = log_file_pos;
-      m_reply_file_name_inited = true;
-
       /* Remove all active transaction nodes before this point. */
       m_active_tranxs->clear_active_tranx_nodes(log_file_name, log_file_pos,
                                                 signal_waiting_transaction);

sql/semisync_master.h

@@ -130,6 +130,7 @@ class Tranx_node_allocator
     trx_node->log_pos= 0;
     trx_node->next= 0;
     trx_node->hash_next= 0;
+    trx_node->acks= 0;
     return trx_node;
   }