From 89e8560cd288aaf949252783ee025f9ad0cc515b Mon Sep 17 00:00:00 2001
From: Tim Felgentreff <timfelgentreff@gmail.com>
Date: Fri, 24 Jun 2022 20:18:27 +0200
Subject: [PATCH] make max iterations for astar configurable

---
 src/include/pathfinder.h             |  2 ++
 src/pathfinder/astar.cpp             | 11 +++++------
 src/pathfinder/script_pathfinder.cpp |  9 +++++++++
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/include/pathfinder.h b/src/include/pathfinder.h
index 1bdcb86e9..16843c177 100644
--- a/src/include/pathfinder.h
+++ b/src/include/pathfinder.h
@@ -199,6 +199,8 @@ extern int AStarMovingUnitCrossingCost;
 extern bool AStarKnowUnseenTerrain;
 /// Cost of using a square we haven't seen before.
 extern int AStarUnknownTerrainCost;
+/// Maximum number of iterations of A* before giving up.
+extern int AStarMaxSearchIterations;
 
 //
 //  Convert heading into direction.
diff --git a/src/pathfinder/astar.cpp b/src/pathfinder/astar.cpp
index 2cfc3fc6f..90a71b77c 100644
--- a/src/pathfinder/astar.cpp
+++ b/src/pathfinder/astar.cpp
@@ -96,6 +96,7 @@ static int AStarMatrixSize;
 /// see pathfinder.h
 int AStarFixedUnitCrossingCost;// = MaxMapWidth * MaxMapHeight;
 int AStarMovingUnitCrossingCost = 5;
+int AStarMaxSearchIterations = INT_MAX;
 bool AStarKnowUnseenTerrain = false;
 int AStarUnknownTerrainCost = 2;
 /// Used to temporary make enemy units unpassable (needs for correct path lenght calculating for automatic targeting alorithm)
@@ -935,6 +936,8 @@ int AStarFindPath(const Vec2i &startPos, const Vec2i &goalPos, int gw, int gh,
 	}
 	Vec2i endPos;
 
+	int counter = AStarMaxSearchIterations;
+
 	//  Begin search
 	while (1) {
 		// Find the best node of from the open set
@@ -952,17 +955,13 @@ int AStarFindPath(const Vec2i &startPos, const Vec2i &goalPos, int gw, int gh,
 			break;
 		}
 
-#if 0
 		// If we have looked too long, then exit.
 		if (!counter--) {
-			// FIXME: Select a "good" point from the open set.
-			// Nearest point to goal.
+			// TODO: Select a "good" point from the open set.
 			AstarDebugPrint("way too long\n");
-			ret = PF_FAILED;
 			ProfileEnd("AStarFindPath");
-			return ret;
+			return PF_UNREACHABLE;
 		}
-#endif
 
 		// Generate successors of this node.
 
diff --git a/src/pathfinder/script_pathfinder.cpp b/src/pathfinder/script_pathfinder.cpp
index 316a32191..6e19e5c35 100644
--- a/src/pathfinder/script_pathfinder.cpp
+++ b/src/pathfinder/script_pathfinder.cpp
@@ -93,6 +93,15 @@ static int CclAStar(lua_State *l)
 			} else {
 				AStarUnknownTerrainCost = i;
 			}
+		} else if (!strcmp(value, "max-search-iterations")) {
+			++j;
+			i = LuaToNumber(l, j + 1);
+			if (i <= 0) {
+				PrintFunction();
+				fprintf(stdout, "Max A* search iterations must be strictly > 0\n");
+			} else {
+				AStarMaxSearchIterations = i;
+			}
 		} else {
 			LuaError(l, "Unsupported tag: %s" _C_ value);
 		}