fix for bug #17494 (The algorithm for calculating execution times is not fully correct)

This also should fix 17493 and 17346, and probably 16397 (not tested).
WL#1034 (Internal CRON)
(post-review commit)


mysql-test/r/events.result:
  update result
mysql-test/t/events.test:
  update test
sql/event.cc:
  seems we get a crash if we compile it this way. better let the worker thread do it,
  this increases the stability.
sql/event_executor.cc:
  kick in more often
sql/event_timed.cc:
  - don't NULLify last_executed
  - implement (fix) better get_next_time() which does not use last_executed as basis
    but STARTS. STARTS is used as basis and the next point of time which is before ENDS,
    if set, is being found. The point > now and (point-starts) % interval_expression == 0.
sql/item_timefunc.cc:
  move calc_time_diff to time.cc as it can be reused in other parts of the 
  server code (see event_timed.cc)
sql/mysql_priv.h:
  export calc_time_diff() moved to time.cc from item_timefunc.cc
sql/sql_show.cc:
  - fix presenting of LAST_EXECUTED
  - cleanup a bit
sql/time.cc:
  - move calc_time_diff() from item_timefunc.cc to here

1 files changed, 76 insertions, 0 deletions

diff --git a/sql/time.cc b/sql/time.cc
index efe1cbf1c09..3c654de23bb 100644
--- a/sql/time.cc
+++ b/sql/time.cc
@@ -833,4 +833,80 @@ invalid_date:
 }
 
 
+/*
+  Calculate difference between two datetime values as seconds + microseconds.
+
+  SYNOPSIS
+    calc_time_diff()
+      l_time1         - TIME/DATE/DATETIME value
+      l_time2         - TIME/DATE/DATETIME value
+      l_sign          - 1 absolute values are substracted,
+                        -1 absolute values are added.
+      seconds_out     - Out parameter where difference between
+                        l_time1 and l_time2 in seconds is stored.
+      microseconds_out- Out parameter where microsecond part of difference
+                        between l_time1 and l_time2 is stored.
+
+  NOTE
+    This function calculates difference between l_time1 and l_time2 absolute
+    values. So one should set l_sign and correct result if he want to take
+    signs into account (i.e. for TIME values).
+
+  RETURN VALUES
+    Returns sign of difference.
+    1 means negative result
+    0 means positive result
+
+*/
+
+bool
+calc_time_diff(TIME *l_time1, TIME *l_time2, int l_sign, longlong *seconds_out,
+               long *microseconds_out)
+{
+  long days;
+  bool neg;
+  longlong microseconds;
+
+  /*
+    We suppose that if first argument is MYSQL_TIMESTAMP_TIME
+    the second argument should be TIMESTAMP_TIME also.
+    We should check it before calc_time_diff call.
+  */
+  if (l_time1->time_type == MYSQL_TIMESTAMP_TIME)  // Time value
+    days= (long)l_time1->day - l_sign * (long)l_time2->day;
+  else
+  {
+    days= calc_daynr((uint) l_time1->year,
+		     (uint) l_time1->month,
+		     (uint) l_time1->day);
+    if (l_time2->time_type == MYSQL_TIMESTAMP_TIME)
+      days-= l_sign * (long)l_time2->day;
+    else
+      days-= l_sign*calc_daynr((uint) l_time2->year,
+			       (uint) l_time2->month,
+			       (uint) l_time2->day);
+  }
+
+  microseconds= ((longlong)days*LL(86400) +
+                 (longlong)(l_time1->hour*3600L +
+                            l_time1->minute*60L +
+                            l_time1->second) -
+                 l_sign*(longlong)(l_time2->hour*3600L +
+                                   l_time2->minute*60L +
+                                   l_time2->second)) * LL(1000000) +
+                (longlong)l_time1->second_part -
+                l_sign*(longlong)l_time2->second_part;
+
+  neg= 0;
+  if (microseconds < 0)
+  {
+    microseconds= -microseconds;
+    neg= 1;
+  }
+  *seconds_out= microseconds/1000000L;
+  *microseconds_out= (long) (microseconds%1000000L);
+  return neg;
+}
+
+
 #endif