many changes to my_getsystime.c:

* my_getsystime() is only an interval timer. Its value can beused for calculating
  time intervals.
* renamed my_getsystime() to my_interval_timer(), to make the semantics
  clearer and let the compiler catch wrong usages of my_getsystime()
  (also future ones, that may come in merges).
* increased its granularity from 100ns to 1ns, old value was for UUID,
  but as UUID can no longer use it directly there is no need to downgrade
  the OS provided value
* fixed the UUID code to anchor the my_interval_timer() on the epoch, as
  required by the UUID standard. That is, this was only needed by UUID,
  and now I've moved it to UUID code from my_getsystime().
* fixed other wrong usages of my_getsystime() - e.g. in calculating
  times for pthread_cond_timedwait. It was buggy and could've caused
  long waits if OS clock would be changed.

5 files changed, 15 insertions, 15 deletions

diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index fd5c47d25cb..ef6bf611637 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -3446,6 +3446,8 @@ err:
 static struct rand_struct uuid_rand;
 static uint nanoseq;
 static ulonglong uuid_time=0;
+static longlong interval_timer_offset;
+
 static char clock_seq_and_node_str[]="-0000-000000000000";
 
 /**
@@ -3473,6 +3475,7 @@ static void set_clock_seq_str()
   uint16 clock_seq= ((uint)(my_rnd(&uuid_rand)*16383)) | UUID_VARIANT;
   tohex(clock_seq_and_node_str+1, clock_seq, 4);
   nanoseq= 0;
+  interval_timer_offset= my_hrtime().val * 10 - my_interval_timer()/100 + UUID_TIME_OFFSET;
 }
 
 String *Item_func_uuid::val_str(String *str)
@@ -3512,7 +3515,7 @@ String *Item_func_uuid::val_str(String *str)
     set_clock_seq_str();
   }
 
-  ulonglong tv= my_getsystime() + UUID_TIME_OFFSET + nanoseq;
+  ulonglong tv= my_interval_timer()/100 + interval_timer_offset + nanoseq;
 
   if (likely(tv > uuid_time))
   {
@@ -3564,7 +3567,7 @@ String *Item_func_uuid::val_str(String *str)
         irrelevant in the new numberspace.
       */
       set_clock_seq_str();
-      tv= my_getsystime() + UUID_TIME_OFFSET;
+      tv= my_interval_timer()/100 + interval_timer_offset;
       nanoseq= 0;
       DBUG_PRINT("uuid",("making new numberspace"));
     }
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 98cf221b679..07d76edcbbf 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -1947,7 +1947,7 @@ static bool cache_thread()
         this thread for handling of new THD object/connection.
       */
       thd->mysys_var->abort= 0;
-      thd->thr_create_utime= my_micro_time();
+      thd->thr_create_utime= microsecond_interval_timer();
       threads.append(thd);
       return(1);
     }
@@ -4907,7 +4907,7 @@ void handle_connection_in_main_thread(THD *thd)
   thread_cache_size=0;			// Safety
   threads.append(thd);
   pthread_mutex_unlock(&LOCK_thread_count);
-  thd->start_utime= my_micro_time();
+  thd->start_utime= microsecond_interval_timer();
   handle_one_connection(thd);
 }
 
@@ -4933,7 +4933,7 @@ void create_thread_to_handle_connection(THD *thd)
     thread_created++;
     threads.append(thd);
     DBUG_PRINT("info",(("creating thread %lu"), thd->thread_id));
-    thd->prior_thr_create_utime= thd->start_utime= my_micro_time();
+    thd->prior_thr_create_utime= thd->start_utime= microsecond_interval_timer();
     if ((error=pthread_create(&thd->real_id,&connection_attrib,
                               handle_one_connection,
                               (void*) thd)))
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 507b2902eda..9a0a9bc5b38 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -2028,17 +2028,14 @@ public:
     {
       start_time= hrtime_to_my_time(user_time);
       start_time_sec_part= hrtime_sec_part(user_time);
-      start_utime= utime_after_lock= my_micro_time();
     }
     else
     {
-      my_hrtime_t hrtime;
-      my_timediff_t timediff;
-      my_micro_and_hrtime(&timediff, &hrtime);
+      my_hrtime_t hrtime= my_hrtime();
       start_time= hrtime_to_my_time(hrtime);
       start_time_sec_part= hrtime_sec_part(hrtime);
-      utime_after_lock= start_utime= timediff.val;
     }
+    start_utime= utime_after_lock= microsecond_interval_timer();
   }
   inline void	set_current_time()
   {
@@ -2051,15 +2048,15 @@ public:
     user_time= t;
     start_time= hrtime_to_my_time(user_time);
     start_time_sec_part= hrtime_sec_part(user_time);
-    start_utime= utime_after_lock= my_micro_time();
+    start_utime= utime_after_lock= microsecond_interval_timer();
   }
   inline void	set_time(my_time_t t, ulong sec_part)
   {
     my_hrtime_t hrtime= { hrtime_from_time(t) + sec_part };
     set_time(hrtime);
   }
-  void set_time_after_lock()  { utime_after_lock= my_micro_time(); }
-  ulonglong current_utime()  { return my_micro_time(); }
+  void set_time_after_lock()  { utime_after_lock= microsecond_interval_timer(); }
+  ulonglong current_utime()  { return microsecond_interval_timer(); }
   inline ulonglong found_rows(void)
   {
     return limit_found_rows;
diff --git a/sql/sql_connect.cc b/sql/sql_connect.cc
index 28c1acc4716..a6e91b0f910 100644
--- a/sql/sql_connect.cc
+++ b/sql/sql_connect.cc
@@ -1084,7 +1084,7 @@ pthread_handler_t handle_one_connection(void *arg)
 {
   THD *thd= (THD*) arg;
 
-  thd->thr_create_utime= my_micro_time();
+  thd->thr_create_utime= microsecond_interval_timer();
 
   if (thread_scheduler.init_new_connection_thread())
   {
diff --git a/sql/sql_profile.cc b/sql/sql_profile.cc
index c661f3744aa..732e7431efc 100644
--- a/sql/sql_profile.cc
+++ b/sql/sql_profile.cc
@@ -221,7 +221,7 @@ void PROF_MEASUREMENT::set_label(const char *status_arg,
 */
 void PROF_MEASUREMENT::collect()
 {
-  time_usecs= (double) my_getsystime() / 10.0;  /* 1 sec was 1e7, now is 1e6 */
+  time_usecs= my_interval_timer() / 1e3;  /* ns to us */
 #ifdef HAVE_GETRUSAGE
   getrusage(RUSAGE_SELF, &rusage);
 #endif