[Freeciv-Dev] Re: [FreeCiv-Cvs] per: Abort possibly infinite loop in ai_unit_rampage...

["Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>]

Skip that last comment ... my turn to think after finger press.

Cheers,
RossW
=====

>This may not work, since if punit has moves left the count is never
>decremented. Move --count test to the front of the while tests to 
>always be decremented.
>
>Cheers,
>RossW
>=====
>
>At 01:48 AM 02/12/09 +0000, Per I. Mathisen wrote:
>>
>>On Sun, 8 Dec 2002 freeciv@xxxxxxxxxxxxxxxxxxx wrote:
>>> Abort possibly infinite loop in ai_unit_rampage() when we are unable to
>>> move or attack our target.
>>>
>>> Patch by Jordi Negrevernis i Font <jorneg@xxxxxxxxxxx> with changes by
>>> me.
>>
>>Ooops. Investigating this more properly, I realize that this will give a
>>number of false positives because we can railroad into empty cities (no
>>movement spent).
>>
>>Still, a way to identify and break potential infinite loops in
>>ai_unit_rampage() is sorely needed. Suggestion pasted below.
>>
>>In any case, the proper fix for the current infinite loops is pasted
>>below. Will be committed.
>>
>>  - Per
>>
>>Index: ai/aitools.c
>>===================================================================
>>RCS file: /home/freeciv/CVS/freeciv/ai/aitools.c,v
>>retrieving revision 1.64
>>diff -u -r1.64 aitools.c
>>--- ai/aitools.c        8 Dec 2002 23:42:37 -0000       1.64
>>+++ ai/aitools.c        9 Dec 2002 01:43:51 -0000
>>@@ -279,6 +279,10 @@
>>   pmove.x = x;
>>   pmove.y = y;
>>   pmove.unid = punit->id;
>>+  if (punit->activity != ACTIVITY_IDLE
>>+      && punit->activity != ACTIVITY_GOTO) {
>>+    handle_unit_activity_request(punit, ACTIVITY_IDLE);
>>+  }
>>   handle_move_unit(unit_owner(punit), &pmove);
>>
>>   if (find_unit_by_id(sanity) && same_pos(x, y, punit->x, punit->y)) {
>>
>>Index: ai/aiunit.c
>>===================================================================
>>RCS file: /home/freeciv/CVS/freeciv/ai/aiunit.c,v
>>retrieving revision 1.235
>>diff -u -r1.235 aiunit.c
>>--- ai/aiunit.c 9 Dec 2002 00:32:12 -0000       1.235
>>+++ ai/aiunit.c 9 Dec 2002 01:46:59 -0000
>>@@ -1057,20 +1057,14 @@
>>
>>**************************************************************************/
>> static struct unit *ai_military_rampage(struct unit *punit, int
>>threshold)
>> {
>>-  int x, y, moves_left, id = punit->id;
>>+  int x, y, id = punit->id;
>>+  int count = punit->moves_left + 1; /* break any infinite loops */
>>
>>-  while (punit && punit->moves_left > 0
>>+  while (punit && punit->moves_left > 0 && count-- > 0
>>          && ai_military_findvictim(punit, &x, &y) >= threshold) {
>>     moves_left = punit->moves_left;
>>     ai_unit_attack(punit, x, y);
>>     punit = find_unit_by_id(id);
>>-    if (punit) {
>>-      if (moves_left == punit->moves_left) {
>>-        /* We were unable to move - avoid infinite loop! */
>>-        UNIT_LOG(LOG_ERROR, punit, "Unable to move/attack at (%d, %d)",
x, y);
>>-        return punit;
>>-      }
>>-    }
>>   }
>>   return punit;
>> }
>>
>>
>>
>>
>>