MDEV-26: Global transaction ID. First alpha release.

Merge of 10.0-mdev26 feature tree into 10.0-base.

Global transaction ID is prepended to each event group in the binlog.

Slave connect can request to start from GTID position instead of specifying
file name/offset of master binlog. This facilitates easy switch to a new
master.

Slave GTID state is stored in a table mysql.rpl_slave_state, which can be
InnoDB to get crash-safe slave state.

GTID includes a replication domain ID, allowing to keep track of distinct
positions for each of multiple masters.

1 files changed, 40 insertions, 0 deletions

diff --git a/sql/sys_vars.h b/sql/sys_vars.h
index 31764aa82a4..b04e3817406 100644
--- a/sql/sys_vars.h
+++ b/sql/sys_vars.h
@@ -2020,3 +2020,43 @@ public:
   }
 };
 
+
+/**
+  Class for @@global.gtid_pos.
+*/
+class Sys_var_gtid_pos: public sys_var
+{
+public:
+  Sys_var_gtid_pos(const char *name_arg,
+          const char *comment, int flag_args, ptrdiff_t off, size_t size,
+          CMD_LINE getopt)
+    : sys_var(&all_sys_vars, name_arg, comment, flag_args, off, getopt.id,
+              getopt.arg_type, SHOW_CHAR, 0, NULL, VARIABLE_NOT_IN_BINLOG,
+              NULL, NULL, NULL)
+  {
+    option.var_type= GET_STR;
+  }
+  bool do_check(THD *thd, set_var *var);
+  bool session_update(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool global_update(THD *thd, set_var *var);
+  bool check_update_type(Item_result type) { return type != STRING_RESULT; }
+  void session_save_default(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+  }
+  void global_save_default(THD *thd, set_var *var)
+  {
+    /* Record the attempt to use default so we can error. */
+    var->value= 0;
+  }
+  uchar *session_value_ptr(THD *thd, LEX_STRING *base)
+  {
+    DBUG_ASSERT(false);
+    return NULL;
+  }
+  uchar *global_value_ptr(THD *thd, LEX_STRING *base);
+};