Add GiveUp exception and include chrono

path_finding.cpp

@@ -415,6 +415,8 @@ boost::optional<linestring_type_fp> find_path(
     bg::append(result, path_surface->get_point_by_index(0));
     bg::reverse(result);
     return make_optional(result);
+  } catch (GiveUp g) {
+    return boost::none;
   }
   return boost::none;
 }

path_finding.hpp

@@ -9,6 +9,8 @@ namespace path_finding {
 
 class PathFindingSurface;
 
+struct GiveUp {};
+
 // Given a target location and a potential path length to get there, determine
 // if it still makes sense to follow the path.  Return true if it does,
 // otherwise false.

surface_vectorial.cpp

@@ -38,6 +38,8 @@ using std::vector;
 using std::cerr;
 using std::endl;
 
+#include <chrono>
+
 #include <utility>
 using std::pair;
 using std::make_pair;
@@ -324,8 +326,9 @@ optional<linestring_type_fp> do_milling(
   auto t1 = system_clock::now();
   path_finding::PathLimiter path_limiter =
       [&](const point_type_fp& waypoint, const coordinate_type_fp& length_so_far) -> bool {
+        tries++;
         if (system_clock::now() - t1 > seconds(1)) {
-          return true;
+          throw path_finding::GiveUp();
         }
         // Return true if this path needs to be clipped.  The distance from
         // a to target so far is length.  At best, we'll have a stright