MDEV-14788 System versioning cannot be based on local timestamps, as it is now

use system time, not @@timestamp

mysql-test/suite/versioning/r/insert.result

@@ -343,3 +343,15 @@ drop procedure test_02;
 drop procedure test_03;
 drop procedure test_04;
 drop procedure test_05;
+set timestamp=1000000019;
+select now() < sysdate();
+now() < sysdate()
+1
+create table t1 (a int) with system versioning;
+insert t1 values (1);
+select * from t1 for system_time as of now(6);
+a
+select * from t1 for system_time as of sysdate(6);
+a
+1
+drop table t1;

mysql-test/suite/versioning/t/insert.test

@@ -240,3 +240,14 @@ drop procedure test_04;
 drop procedure test_05;
 
 -- source suite/versioning/common_finish.inc
+
+#
+# MDEV-14788 System versioning cannot be based on local timestamps, as it is now
+#
+set timestamp=1000000019;
+select now() < sysdate();
+create table t1 (a int) with system versioning;
+insert t1 values (1);
+select * from t1 for system_time as of now(6);
+select * from t1 for system_time as of sysdate(6);
+drop table t1;

sql/sql_class.h

@@ -2358,6 +2358,8 @@ class THD :public Statement,
   // track down slow pthread_create
   ulonglong  prior_thr_create_utime, thr_create_utime;
   ulonglong  utime_after_query;
+  my_time_t  system_time;
+  ulong      system_time_sec_part;
 
   // Process indicator
   struct {
@@ -3377,36 +3379,37 @@ class THD :public Statement,
   MYSQL_TIME query_start_TIME();
 
 private:
-  void start_time_inc()
+  bool system_time_ge(my_time_t secs, ulong usecs)
   {
-    ++start_time_sec_part;
-    if (start_time_sec_part == HRTIME_RESOLUTION)
-    {
-      ++start_time;
-      start_time_sec_part= 0;
-    }
-  }
-
-  bool start_time_ge(my_time_t secs, ulong usecs)
-  {
-    return (start_time == secs && start_time_sec_part >= usecs) ||
-        start_time > secs;
+    return (system_time == secs && system_time_sec_part >= usecs) ||
+        system_time > secs;
   }
 
-  void set_current_time()
+  void set_system_time()
   {
     my_hrtime_t hrtime= my_hrtime();
     my_time_t secs= hrtime_to_my_time(hrtime);
     ulong usecs= hrtime_sec_part(hrtime);
-    if (start_time_ge(secs, usecs))
+    if (system_time_ge(secs, usecs))
     {
-      start_time_inc();
+      if (++system_time_sec_part == HRTIME_RESOLUTION)
+      {
+        ++system_time;
+        system_time_sec_part= 0;
+      }
     }
     else
     {
-      start_time= secs;
-      start_time_sec_part= usecs;
+      system_time= secs;
+      system_time_sec_part= usecs;
+    }
   }
+
+  void set_current_time()
+  {
+    set_system_time();
+    start_time= system_time;
+    start_time_sec_part= system_time_sec_part;
     PSI_CALL_set_thread_start_time(start_time);
   }
 
@@ -3415,6 +3418,7 @@ class THD :public Statement,
   {
     if (user_time.val)
     {
+      set_system_time();
       start_time= hrtime_to_my_time(user_time);
       start_time_sec_part= hrtime_sec_part(user_time);
       PSI_CALL_set_thread_start_time(start_time);

sql/table.cc

@@ -7768,7 +7768,9 @@ void TABLE::vers_update_fields()
   {
     if (!vers_write)
       return;
-    if (vers_start_field()->set_time())
+    vers_start_field()->set_notnull();
+    if (vers_start_field()->store_timestamp(in_use->system_time,
+                                            in_use->system_time_sec_part))
       DBUG_ASSERT(0);
   }
   else
@@ -8620,9 +8622,9 @@ bool TR_table::update(ulonglong start_id, ulonglong end_id)
   if (!table && open())
     return true;
 
-  timeval start_time= {thd->start_time, long(thd->start_time_sec_part)};
+  timeval start_time= {thd->system_time, long(thd->system_time_sec_part)};
   thd->set_start_time();
-  timeval end_time= {thd->start_time, long(thd->start_time_sec_part)};
+  timeval end_time= {thd->system_time, long(thd->system_time_sec_part)};
   store(FLD_TRX_ID, start_id);
   store(FLD_COMMIT_ID, end_id);
   store(FLD_BEGIN_TS, start_time);