Linkgraph: Use an arena allocator for path objects.

Fixes leaks when job is aborted early.

src/linkgraph/flowmapper.cpp

@@ -60,10 +60,7 @@ void FlowMapper::Run(LinkGraphJob &job) const
 			}
 		}
 		/* Clear paths. */
-		PathList &paths = node.Paths();
-		for (PathList::iterator i = paths.begin(); i != paths.end(); ++i) {
-			delete *i;
-		}
-		paths.clear();
+		node.Paths().clear();
 	}
+	job.path_allocator.ResetArena();
 }

src/linkgraph/linkgraphjob.h

@@ -13,6 +13,7 @@
 #define LINKGRAPHJOB_H
 
 #include "../thread/thread.h"
+#include "../core/dyn_arena_alloc.hpp"
 #include "linkgraph.h"
 #include <list>
 #include <memory>
@@ -77,6 +78,8 @@ protected:
 
 public:
 
+	DynUniformArenaAllocator path_allocator; ///< Arena allocator used for paths
+
 	bool IsJobAborted() const;
 
 	/**

src/linkgraph/mcf.cpp

@@ -378,8 +378,11 @@ void MultiCommodityFlow::Dijkstra(NodeID source_node, PathVector &paths)
 	Tedge_iterator iter(this->job);
 	uint size = this->job.Size();
 	paths.resize(size, NULL);
+
+	this->job.path_allocator.SetParameters(sizeof(AnnosWrapper<Tannotation>), (8192 - 32) / sizeof(AnnosWrapper<Tannotation>));
+
 	for (NodeID node = 0; node < size; ++node) {
-		AnnosWrapper<Tannotation> *anno = new AnnosWrapper<Tannotation>(node, node == source_node);
+		AnnosWrapper<Tannotation> *anno = new (this->job.path_allocator.Allocate()) AnnosWrapper<Tannotation>(node, node == source_node);
 		anno->UpdateAnnotation();
 		anno->self_iter = annos.insert(AnnoSetItem<Tannotation>(anno)).first;
 		paths[node] = anno;
@@ -431,12 +434,12 @@ void MultiCommodityFlow::CleanupPaths(NodeID source_id, PathVector &paths)
 			path->Detach();
 			if (path->GetNumChildren() == 0) {
 				paths[path->GetNode()] = NULL;
-				delete path;
+				this->job.path_allocator.Free(path);
 			}
 			path = parent;
 		}
 	}
-	delete source;
+	this->job.path_allocator.Free(source);
 	paths.clear();
 }