(svn r14258) -Codechange: rework the way to query the vehicle hash to make sure it always results in the same irregardless of the order of the hash-linked-list.

-Fix: desync in PBS reservation following, vehicle flooding and road vehicle overtake/follow code.

1 files changed, 14 insertions, 16 deletions

diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 42e1d02ff..328c39e88 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -1694,24 +1694,22 @@ static Vehicle *TrainApproachingCrossingEnum(Vehicle *v, void *data)
 /**
  * Finds a vehicle approaching rail-road crossing
  * @param tile tile to test
- * @return pointer to vehicle approaching the crossing
+ * @return true if a vehicle is approaching the crossing
  * @pre tile is a rail-road crossing
  */
-static Vehicle *TrainApproachingCrossing(TileIndex tile)
+static bool TrainApproachingCrossing(TileIndex tile)
 {
 	assert(IsLevelCrossingTile(tile));
 
 	DiagDirection dir = AxisToDiagDir(GetCrossingRailAxis(tile));
 	TileIndex tile_from = tile + TileOffsByDiagDir(dir);
 
-	Vehicle *v = VehicleFromPos(tile_from, &tile, &TrainApproachingCrossingEnum);
-
-	if (v != NULL) return v;
+	if (HasVehicleOnPos(tile_from, &tile, &TrainApproachingCrossingEnum)) return true;
 
 	dir = ReverseDiagDir(dir);
 	tile_from = tile + TileOffsByDiagDir(dir);
 
-	return VehicleFromPos(tile_from, &tile, &TrainApproachingCrossingEnum);
+	return HasVehicleOnPos(tile_from, &tile, &TrainApproachingCrossingEnum);
 }
 
 
@@ -1726,7 +1724,7 @@ void UpdateLevelCrossing(TileIndex tile, bool sound)
 	assert(IsLevelCrossingTile(tile));
 
 	/* train on crossing || train approaching crossing || reserved */
-	bool new_state = VehicleFromPos(tile, NULL, &TrainOnTileEnum) != NULL || TrainApproachingCrossing(tile) || GetCrossingReservation(tile);
+	bool new_state = HasVehicleOnPos(tile, NULL, &TrainOnTileEnum) || TrainApproachingCrossing(tile) || GetCrossingReservation(tile);
 
 	if (new_state != IsCrossingBarred(tile)) {
 		if (new_state && sound) {
@@ -3028,7 +3026,7 @@ bool TryPathReserve(Vehicle *v, bool mark_as_stuck, bool first_tile_okay)
 		}
 	}
 
-	Vehicle *other_train = NULL;
+	bool other_train = false;
 	PBSTileInfo origin = FollowTrainReservation(v, &other_train);
 	/* If we have a reserved path and the path ends at a safe tile, we are finished already. */
 	if (origin.okay && (v->tile != origin.tile || first_tile_okay)) {
@@ -3041,7 +3039,7 @@ bool TryPathReserve(Vehicle *v, bool mark_as_stuck, bool first_tile_okay)
 	 * This can only happen when tracks and signals are changed. A crash
 	 * is probably imminent, don't do any further reservation because
 	 * it might cause stale reservations. */
-	if (other_train != NULL && v->tile != origin.tile) {
+	if (other_train && v->tile != origin.tile) {
 		if (mark_as_stuck) MarkTrainAsStuck(v);
 		return false;
 	}
@@ -3518,10 +3516,10 @@ static void CheckTrainCollision(Vehicle *v)
 
 	/* find colliding vehicles */
 	if (v->u.rail.track == TRACK_BIT_WORMHOLE) {
-		VehicleFromPos(v->tile, &tcc, FindTrainCollideEnum);
-		VehicleFromPos(GetOtherTunnelBridgeEnd(v->tile), &tcc, FindTrainCollideEnum);
+		FindVehicleOnPos(v->tile, &tcc, FindTrainCollideEnum);
+		FindVehicleOnPos(GetOtherTunnelBridgeEnd(v->tile), &tcc, FindTrainCollideEnum);
 	} else {
-		VehicleFromPosXY(v->x_pos, v->y_pos, &tcc, FindTrainCollideEnum);
+		FindVehicleOnPosXY(v->x_pos, v->y_pos, &tcc, FindTrainCollideEnum);
 	}
 
 	/* any dead -> no crash */
@@ -3652,7 +3650,7 @@ static void TrainController(Vehicle *v, Vehicle *nomove, bool update_image)
 								exitdir = ReverseDiagDir(exitdir);
 
 								/* check if a train is waiting on the other side */
-								if (VehicleFromPos(o_tile, &exitdir, &CheckVehicleAtSignal) == NULL) return;
+								if (!HasVehicleOnPos(o_tile, &exitdir, &CheckVehicleAtSignal)) return;
 							}
 						}
 
@@ -3819,9 +3817,9 @@ reverse_train_direction:
 }
 
 /** Collect trackbits of all crashed train vehicles on a tile
- * @param v Vehicle passed from VehicleFromPos()
+ * @param v Vehicle passed from Find/HasVehicleOnPos()
  * @param data trackdirbits for the result
- * @return NULL to not abort VehicleFromPos()
+ * @return NULL to iterate over all vehicles on the tile.
  */
 static Vehicle *CollectTrackbitsFromCrashedVehiclesEnum(Vehicle *v, void *data)
 {
@@ -3894,7 +3892,7 @@ static void DeleteLastWagon(Vehicle *v)
 
 		/* If there are still crashed vehicles on the tile, give the track reservation to them */
 		TrackBits remaining_trackbits = TRACK_BIT_NONE;
-		VehicleFromPos(tile, &remaining_trackbits, CollectTrackbitsFromCrashedVehiclesEnum);
+		FindVehicleOnPos(tile, &remaining_trackbits, CollectTrackbitsFromCrashedVehiclesEnum);
 
 		/* It is important that these two are the first in the loop, as reservation cannot deal with every trackbit combination */
 		assert(TRACK_BEGIN == TRACK_X && TRACK_Y == TRACK_BEGIN + 1);