improve performance of triangle counting (#48)

include/scea/algo/tc.hpp

@@ -21,18 +21,16 @@ class TriangleCounting : public Algo {
 
     galois::do_all(galois::iterate((uint64_t)0, g.size()),
                    [&](uint64_t const& v0) {
+                     g.sort_edges(v0);
                      g.for_each_edge(v0, [&](uint64_t const& v1) {
                        if (v0 >= v1)
                          return;
                        g.for_each_edge(v1, [&](uint64_t const& v2) {
                          // Check (v0, v2) exists?
                          if (v1 >= v2)
                            return;
-                         g.for_each_edge(v0, [&](uint64_t const& v0_neighbor) {
-                           if (v0_neighbor == v2)
-                             numTriangles += 1;
-                           return;
-                         });
+                         if (g.find_edge_sorted(v0, v2))
+                           numTriangles += 1;
                        });
                      });
                    });

include/scea/graph/adj.hpp

@@ -33,6 +33,14 @@ class AdjGraph : public MutableGraph {
     for (auto const& dst : edges[src])
       callback(dst);
   }
+
+  void sort_edges(uint64_t src) {
+    std::sort(edges[src].begin(), edges[src].end());
+  }
+
+  bool find_edge_sorted(uint64_t src, uint64_t dst) {
+    return std::binary_search(edges[src].begin(), edges[src].end(), dst);
+  }
 };
 
 } // namespace scea::graph

include/scea/graph/csr.hpp

@@ -45,6 +45,11 @@ class LC_CSR : public MutableGraph {
     for (auto const& edge : m_graph->edges(src))
       callback(m_graph->getEdgeDst(edge));
   }
+
+  void sort_edges(uint64_t src) override { m_graph->sortEdgesByDst(src); }
+  bool find_edge_sorted(uint64_t src, uint64_t dst) override {
+    return m_graph->findEdgeSortedByDst(src, dst) != m_graph->edge_end(src);
+  }
 };
 
 } // namespace scea::graph

include/scea/graph/lscsr.hpp

@@ -40,6 +40,12 @@ class LS_CSR : public MutableGraph {
     for (auto const& edge : graph.edges(src))
       callback(graph.getEdgeDst(edge));
   }
+
+  void sort_edges(uint64_t src) override { graph.sortEdges(src); }
+
+  bool find_edge_sorted(uint64_t src, uint64_t dst) override {
+    return graph.findEdgeSorted(src, dst);
+  }
 };
 
 } // namespace scea::graph

include/scea/graph/morph.hpp

@@ -42,6 +42,15 @@ class MorphGraph : public MutableGraph {
     for (auto const& edge : graph.edges(vertices[src]))
       callback(graph.getData(graph.getEdgeDst(edge)));
   }
+
+  void sort_edges(uint64_t src) override {
+    graph.sortEdgesByDst(vertices[src]);
+  }
+
+  bool find_edge_sorted(uint64_t src, uint64_t dst) override {
+    return graph.findEdgeSortedByDst(vertices[src], vertices[dst]) !=
+           graph.edge_end(vertices[src]);
+  }
 };
 
 } // namespace scea::graph

include/scea/graph/mutable_graph_interface.hpp

@@ -19,6 +19,8 @@ class MutableGraph {
   virtual void post_ingest()                                                = 0;
   virtual void for_each_edge(uint64_t src,
                              std::function<void(uint64_t const&)> callback) = 0;
+  virtual void sort_edges(uint64_t src)                                     = 0;
+  virtual bool find_edge_sorted(uint64_t src, uint64_t dst)                 = 0;
 };
 
 } // namespace scea::graph