budget: Avoid unnecessary work

Ship, plane and land unit repairs depend on and change the state of
the sector.  To predict repairs, we need to predict the state of the
sector before repairs.  The obvious way to do that is to simulate the
sector update and all ship, plane and land unit updates there in the
correct order.

Until recently, we simulated only own sectors, ships, planes and land
units.  Wrong when foreign sectors, ships, planes or land units are
involved.  The fix (commit 70f6964) makes budget simulate all
countries.  Correct, but does much more work than necessary.  With a
little effort, we can track what needs to be simulated.

Use the bp map for tracking.  We need to mark the player's sectors and
all sectors where he has ships, planes or land units.  Do the former
in bp_alloc(), and the latter in prep_ships(), prep_planes(),
prep_lands().

Skip sectors not so marked.  This requires delaying prepare_sects()
until after prep_ships(), prep_planes(), prep_lands().  Their order
doesn't actually matter: prep_ships() & friends only spend money, and
nothing in preparation depends on whether the country is still
solvent.

Skip ships, planes and land units in sectors not so marked.

This speeds up budget by around a third in my testing, more for small
countries.  Roughly 15% slower than before the fix for repairs abroad.
The update has to do a bit more work than before, but the performance
difference is lost in the noise.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

src/lib/update/bp.c

@@ -41,8 +41,12 @@
 #include <config.h>
 
 #include <stdlib.h>
+#include "empobj.h"
 #include "optlist.h"
+#include "player.h"
+#include "prototypes.h"
 #include "update.h"
+#include "xy.h"
 
 /* Item types we want to track. */
 enum bp_item_idx {
@@ -51,6 +55,12 @@ enum bp_item_idx {
     BP_MAX = BP_HCM
 };
 
+enum bp_status {
+    BP_UNUSED,			/* not tracked, values are invalid */
+    BP_WANTED,			/* tracked, values are still invalid */
+    BP_USED			/* tracked, values are valid */
+};
+
 /*
  * Stuff to track for a sector.
  * A bp map is an array of these.
@@ -58,7 +68,7 @@ enum bp_item_idx {
 struct bp {
     short bp_item[BP_MAX + 1];
     short bp_avail;
-    unsigned char bp_tracked;
+    unsigned char bp_status;
 };
 
 /* Map i_type to enum bp_item_idx. */
@@ -68,6 +78,33 @@ static enum bp_item_idx bud_key[I_MAX + 1] = {
     BP_LCM, BP_HCM, BP_NONE, BP_NONE
 };
 
+/* Return true when @bp doesn't track @sp. */
+int
+bp_skip_sect(struct bp *bp, struct sctstr *sp)
+{
+    return bp && bp[sp->sct_uid].bp_status == BP_UNUSED;
+}
+
+/* Return true when @bp doesn't track @unit's sector. */
+int
+bp_skip_unit(struct bp *bp, struct empobj *unit)
+{
+    return bp && bp[XYOFFSET(unit->x, unit->y)].bp_status == BP_UNUSED;
+}
+
+/* If @unit belongs to the player, start tracking its sector in @bp. */
+void
+bp_consider_unit(struct bp *bp, struct empobj *unit)
+{
+    int id;
+
+    if (!bp || unit->own != player->cnum)
+	return;
+    id = XYOFFSET(unit->x, unit->y);
+    if (bp[id].bp_status == BP_UNUSED)
+	bp[id].bp_status = BP_WANTED;
+}
+
 /* Set the values tracked in @bp for sector @sp to the values in @sp. */
 void
 bp_set_from_sect(struct bp *bp, struct sctstr *sp)
@@ -83,11 +120,11 @@ bp_set_from_sect(struct bp *bp, struct sctstr *sp)
 	    bp[sp->sct_uid].bp_item[idx] = sp->sct_item[i];
     }
     bp[sp->sct_uid].bp_avail = sp->sct_avail;
-    bp[sp->sct_uid].bp_tracked = 1;
+    bp[sp->sct_uid].bp_status = BP_USED;
 }
 
 /*
- * Copy the values tracked in @bp for sector @sp back to @sp.
+ * Copy the values tracked in @bp for sector @sp back to it.
  * Values must have been set with bp_set_from_sect().
  */
 void
@@ -96,7 +133,7 @@ bp_to_sect(struct bp *bp, struct sctstr *sp)
     i_type i;
     enum bp_item_idx idx;
 
-    if (CANT_HAPPEN(!bp[sp->sct_uid].bp_tracked))
+    if (CANT_HAPPEN(bp[sp->sct_uid].bp_status != BP_USED))
 	return;
 
     for (i = I_NONE + 1; i <= I_MAX; i++) {
@@ -110,6 +147,7 @@ bp_to_sect(struct bp *bp, struct sctstr *sp)
 /*
  * Return a new bp map.
  * Caller should pass it to free() when done with it.
+ * The map initially tracks the sectors belonging to the player.
  */
 struct bp *
 bp_alloc(void)
@@ -119,6 +157,8 @@ bp_alloc(void)
     int i;
 
     for (i = 0; i < n; i++)
-	bp[i].bp_tracked = 0;
+	bp[i].bp_status = getsectid(i)->sct_own == player->cnum
+	    ? BP_WANTED : BP_UNUSED;
+
     return bp;
 }

src/lib/update/land.c

@@ -53,7 +53,7 @@ static void landrepair(struct lndstr *, struct natstr *, struct bp *,
 		       int, struct budget *);
 static int feed_land(struct lndstr *, int);
 
-void prep_lands(int etus)
+void prep_lands(int etus, struct bp *bp)
 {
     int mil, i;
     double mil_pay;
@@ -69,6 +69,7 @@ void prep_lands(int etus)
 	    continue;
 	}
 
+	bp_consider_unit(bp, (struct empobj *)lp);
 	mil = lp->lnd_item[I_MILIT];
 	mil_pay = mil * etus * money_mil;
 	nat_budget[lp->lnd_own].mil.count += mil;
@@ -87,6 +88,8 @@ prod_land(int etus, struct bp *bp, int build)
     for (i = 0; (lp = getlandp(i)); i++) {
 	if (lp->lnd_own == 0)
 	    continue;
+	if (bp_skip_unit(bp, (struct empobj *)lp))
+	    continue;
 	upd_land(lp, etus, bp, build);
     }
 }

src/lib/update/main.c

@@ -90,12 +90,12 @@ update_main(void)
 	nat_budget[n].start_money = nat_budget[n].money = np->nat_money;
     }
 
+    prep_ships(etu, NULL);
+    prep_planes(etu, NULL);
+    prep_lands(etu, NULL);
     logerror("preparing sectors...");
     prepare_sects(etu, NULL);
     logerror("done preparing sectors.");
-    prep_ships(etu);
-    prep_planes(etu);
-    prep_lands(etu);
     for (i = 0; i < MAXNOC; i++)
 	pay_reserve(getnatp(i), etu);
 

src/lib/update/plane.c

@@ -48,7 +48,7 @@ static void upd_plane(struct plnstr *, int, struct bp *, int);
 static void planerepair(struct plnstr *, struct natstr *, struct bp *,
 			int, struct budget *);
 
-void prep_planes(int etus)
+void prep_planes(int etus, struct bp *bp)
 {
     int mil, i;
     double mil_pay;
@@ -64,6 +64,7 @@ void prep_planes(int etus)
 	    continue;
 	}
 
+	bp_consider_unit(bp, (struct empobj *)pp);
 	mil = plchr[pp->pln_type].pl_mat[I_MILIT];
 	/* flight pay is 5x the pay received by other military */
 	mil_pay = mil * etus * money_mil * 5;
@@ -82,6 +83,8 @@ prod_plane(int etus, struct bp *bp, int buildem)
     for (i = 0; (pp = getplanep(i)); i++) {
 	if (pp->pln_own == 0)
 	    continue;
+	if (bp_skip_unit(bp, (struct empobj *)pp))
+	    continue;
 	upd_plane(pp, etus, bp, buildem);
     }
 }

src/lib/update/prepare.c

@@ -76,6 +76,8 @@ prepare_sects(int etu, struct bp *bp)
     }
 
     for (n = 0; NULL != (sp = getsectid(n)); n++) {
+	if (bp_skip_sect(bp, sp))
+	    continue;
 	bp_set_from_sect(bp, sp);
 	if (sp->sct_type == SCT_WATER || sp->sct_type == SCT_SANCT)
 	    continue;

src/lib/update/sect.c

@@ -233,6 +233,8 @@ produce_sect(int etu, struct bp *bp)
     double cost;
 
     for (n = 0; NULL != (sp = getsectid(n)); n++) {
+	if (bp_skip_sect(bp, sp))
+	    continue;
 	if (sp->sct_type == SCT_WATER || sp->sct_type == SCT_SANCT)
 	    continue;
 

src/lib/update/ship.c

@@ -56,7 +56,7 @@ static void shiprepair(struct shpstr *, struct natstr *, struct bp *,
 static void ship_produce(struct shpstr *, int, struct budget *);
 static int feed_ship(struct shpstr *, int);
 
-void prep_ships(int etus)
+void prep_ships(int etus, struct bp *bp)
 {
     int mil, i;
     double mil_pay;
@@ -72,6 +72,7 @@ void prep_ships(int etus)
 	    continue;
 	}
 
+	bp_consider_unit(bp, (struct empobj *)sp);
 	mil = sp->shp_item[I_MILIT];
 	mil_pay = mil * etus * money_mil;
 	nat_budget[sp->shp_own].mil.count += mil;
@@ -90,6 +91,8 @@ prod_ship(int etus, struct bp *bp, int build)
     for (i = 0; (sp = getshipp(i)); i++) {
 	if (sp->shp_own == 0)
 	    continue;
+	if (bp_skip_unit(bp, (struct empobj *)sp))
+	    continue;
 	upd_ship(sp, etus, bp, build);
     }
 }