Author: jtn
Date: Tue Nov 15 11:21:02 2016
New Revision: 34512
URL: http://svn.gna.org/viewcvs/freeciv?rev=34512&view=rev
Log:
Small optimisation to autoattack transport depth check.
See gna patch #7985.
Modified:
trunk/server/unittools.c
Modified: trunk/server/unittools.c
URL:
http://svn.gna.org/viewcvs/freeciv/trunk/server/unittools.c?rev=34512&r1=34511&r2=34512&view=diff
==============================================================================
--- trunk/server/unittools.c (original)
+++ trunk/server/unittools.c Tue Nov 15 11:21:02 2016
@@ -3040,9 +3040,9 @@
/**************************************************************************
This function is passed to autoattack_prob_list_sort() to sort a list of
units and action probabilities according to their win chance against the
- autoattack target modified by transportation relationships.
-
- The reason for making sure that a cargo unit is ahead of it
+ autoattack target, modified by transportation relationships.
+
+ The reason for making sure that a cargo unit is ahead of its
transporter(s) is to leave transports out of combat if at all possible.
(The transport could be destroyed during combat.)
**************************************************************************/
@@ -3053,19 +3053,35 @@
const struct unit *q1unit = game_unit_by_number((*q1)->unit_id);
/* Sort by transport depth first. This makes sure that no transport
- * attacks before its cargo does. */
- if (unit_transport_depth(p1unit) != unit_transport_depth(q1unit)) {
- /* The units have a different number of recursive transporters. */
- return unit_transport_depth(q1unit) - unit_transport_depth(p1unit);
- } else {
- /* Put the units with the highest probability of success first. The up
- * side of this is that units with bonuses against the victim attacks
- * before other units. The downside is that strong units can be lead
- * away by sacrificial units. */
- return (-1
- /* Assume the worst. */
- * action_prob_cmp_pessimist((*p1)->prob, (*q1)->prob));
- }
+ * attacks before its cargo does -- cargo sorts earlier in the list. */
+ {
+ const struct unit *p1trans = p1unit, *q1trans = q1unit;
+
+ /* Walk the transport stacks in parallel, so as to bail out as soon as
+ * one of them is empty (avoid walking deep stacks more often than
+ * necessary). */
+ while (p1trans && q1trans) {
+ p1trans = unit_transport_get(p1trans);
+ q1trans = unit_transport_get(q1trans);
+ }
+ if (!p1trans && q1trans) {
+ /* q1 is at greater depth (perhaps it's p1's cargo). It should sort
+ * earlier in the list (p1 > q1). */
+ return 1;
+ } else if (p1trans && !q1trans) {
+ /* p1 is at greater depth, so should sort earlier (p1 < q1). */
+ return -1;
+ }
+ /* else same depth, so move on to checking win chance: */
+ }
+
+ /* Put the units with the highest probability of success first. The up
+ * side of this is that units with bonuses against the victim attacks
+ * before other units. The downside is that strong units can be led
+ * away by sacrificial units. */
+ return (-1
+ /* Assume the worst. */
+ * action_prob_cmp_pessimist((*p1)->prob, (*q1)->prob));
}
/*****************************************************************
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