Monitor recursion depth and abort if too deep

onthegomap · Nov 7, 2024 · 4bb3b49 · 4bb3b49
1 parent 46a42da
commit 4bb3b49
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Showing 2 changed files with 22 additions and 7 deletions.
diff --git a/...ler-benchmarks/src/main/java/com/onthegomap/planetiler/benchmarks/BenchmarkLineMerge.java b/...ler-benchmarks/src/main/java/com/onthegomap/planetiler/benchmarks/BenchmarkLineMerge.java
@@ -48,13 +48,13 @@ public static void main(String[] args) throws Exception {
         lm.add(geom);
         return lm.getMergedLineStrings();
       });
-      // time("loop(20.0)", geom -> {
-      //   var lm = new LoopLineMerger();
-      //   lm.setLoopMinLength(20.0);
-      //   lm.setMinLength(0.1);
-      //   lm.add(geom);
-      //   return lm.getMergedLineStrings();
-      // });
+      time("loop(20.0)", geom -> {
+        var lm = new LoopLineMerger();
+        lm.setLoopMinLength(20.0);
+        lm.setMinLength(0.1);
+        lm.add(geom);
+        return lm.getMergedLineStrings();
+      });
     }
     System.err.println(numLines);
   }

diff --git a/planetiler-core/src/main/java/com/onthegomap/planetiler/util/LoopLineMerger.java b/planetiler-core/src/main/java/com/onthegomap/planetiler/util/LoopLineMerger.java
@@ -105,6 +105,11 @@ private void removeLoops() {
             }
           }
         }
+        else {
+          // MAX_RECURSION_DEPTH was reached. On other edges of the graph the same
+          // will happen. Abort merging loops...
+          return;
+        }
       }
     }
   }
@@ -119,7 +124,17 @@ List<List<Edge>> findAllPaths(Node start, Node end, double maxLength) {
       }
     }
 
+    var MAX_RECURSION_DEPTH = 1e6;
+    var currentDepth = 0;
+
     while (!queue.isEmpty()) {
+
+      currentDepth += 1;
+      if (currentDepth > MAX_RECURSION_DEPTH) {
+        System.out.println("Warning: max recursion depth reached. Unable to perform loop merging...");
+        return new ArrayList<>();
+      }
+
       List<Edge> currentPath = queue.poll();
       Node currentPoint = currentPath.getLast().to;