refactor: remove legacy two-hop implementation

KaHIP · Nov 14, 2024 · c9e4d52 · c9e4d52
1 parent e5efcee
commit c9e4d52
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Showing 6 changed files with 6 additions and 77 deletions.
diff --git a/kaminpar-dist/coarsening/clustering/lp/global_lp_clusterer.h b/kaminpar-dist/coarsening/clustering/lp/global_lp_clusterer.h
@@ -12,6 +12,7 @@
 #include "kaminpar-dist/datastructures/distributed_graph.h"
 
 namespace kaminpar::dist {
+
 class GlobalLPClusterer : public Clusterer {
 public:
   explicit GlobalLPClusterer(const Context &ctx);
@@ -31,4 +32,5 @@ class GlobalLPClusterer : public Clusterer {
 private:
   std::unique_ptr<class GlobalLPClusteringImplWrapper> _impl;
 };
+
 } // namespace kaminpar::dist
diff --git a/kaminpar-shm/coarsening/clustering/lp_clusterer.cc b/kaminpar-shm/coarsening/clustering/lp_clusterer.cc
@@ -122,9 +122,6 @@ class LPClusteringImpl final
     case TwoHopStrategy::CLUSTER_THREADWISE:
       Base::cluster_two_hop_nodes_threadwise();
       break;
-    case TwoHopStrategy::LEGACY:
-      handle_two_hop_clustering_legacy();
-      break;
     case TwoHopStrategy::DISABLE:
       break;
     }
@@ -160,76 +157,6 @@ class LPClusteringImpl final
     return (1.0 - 1.0 * _current_num_clusters / _graph->n()) <= _lp_ctx.two_hop_threshold;
   }
 
-  // @todo: old implementation that should no longer be used
-  void handle_two_hop_clustering_legacy() {
-    // Reset _favored_clusters entries for nodes that are not considered for
-    // 2-hop clustering, i.e., nodes that are already clustered with at least one other node or
-    // nodes that have more weight than max_weight/2.
-    // Set _favored_clusters to dummy entry _graph->n() for isolated nodes
-    tbb::parallel_for<NodeID>(0, _graph->n(), [&](const NodeID u) {
-      if (u != cluster(u)) {
-        Base::_favored_clusters[u] = u;
-      } else {
-        const auto initial_weight = initial_cluster_weight(u);
-        const auto current_weight = ClusterWeightBase::cluster_weight(u);
-        const auto max_weight = max_cluster_weight(u);
-        if (current_weight != initial_weight || current_weight > max_weight / 2) {
-          Base::_favored_clusters[u] = u;
-        }
-      }
-    });
-
-    tbb::parallel_for<NodeID>(0, _graph->n(), [&](const NodeID u) {
-      // Abort once we have merged enough clusters to achieve the configured minimum shrink factor
-      if (Base::should_stop()) {
-        return;
-      }
-
-      // Skip nodes that should not be considered during 2-hop clustering
-      const NodeID favored_leader = Base::_favored_clusters[u];
-      if (favored_leader == u) {
-        return;
-      }
-
-      do {
-        // If this works, we set ourself as clustering partners for nodes that have the same favored
-        // cluster we have
-        NodeID expected_value = favored_leader;
-        if (__atomic_compare_exchange_n(
-                &Base::_favored_clusters[favored_leader],
-                &expected_value,
-                u,
-                false,
-                __ATOMIC_SEQ_CST,
-                __ATOMIC_SEQ_CST
-            )) {
-          break;
-        }
-
-        // If this did not work, there is another node that has the same favored cluster
-        // Try to join the cluster of that node
-        const NodeID partner = expected_value;
-        if (__atomic_compare_exchange_n(
-                &Base::_favored_clusters[favored_leader],
-                &expected_value,
-                favored_leader,
-                false,
-                __ATOMIC_SEQ_CST,
-                __ATOMIC_SEQ_CST
-            )) {
-          if (ClusterWeightBase::move_cluster_weight(
-                  u, partner, ClusterWeightBase::cluster_weight(u), max_cluster_weight(partner)
-              )) {
-            move_node(u, partner);
-            --_current_num_clusters;
-          }
-
-          break;
-        }
-      } while (true);
-    });
-  }
-
 public:
   [[nodiscard]] NodeID initial_cluster(const NodeID u) {
     return u;

diff --git a/kaminpar-shm/coarsening/clustering/noop_clusterer.h b/kaminpar-shm/coarsening/clustering/noop_clusterer.h
@@ -14,6 +14,7 @@
 #include "kaminpar-common/datastructures/static_array.h"
 
 namespace kaminpar::shm {
+
 class NoopClusterer : public Clusterer {
 public:
   NoopClusterer() = default;
@@ -43,4 +44,5 @@ class NoopClusterer : public Clusterer {
     tbb::parallel_for<NodeID>(0, graph.n(), [&](const NodeID i) { clustering[i] = i; });
   }
 };
+
 } // namespace kaminpar::shm
diff --git a/kaminpar-shm/context_io.cc b/kaminpar-shm/context_io.cc
@@ -303,8 +303,6 @@ std::ostream &operator<<(std::ostream &out, const TwoHopStrategy strategy) {
     return out << "cluster";
   case TwoHopStrategy::CLUSTER_THREADWISE:
     return out << "cluster-threadwise";
-  case TwoHopStrategy::LEGACY:
-    return out << "legacy";
   }
 
   return out << "<invalid>";
@@ -317,7 +315,6 @@ std::unordered_map<std::string, TwoHopStrategy> get_two_hop_strategies() {
       {"match-threadwise", TwoHopStrategy::MATCH_THREADWISE},
       {"cluster", TwoHopStrategy::CLUSTER},
       {"cluster-threadwise", TwoHopStrategy::CLUSTER_THREADWISE},
-      {"legacy", TwoHopStrategy::LEGACY},
   };
 }
 

diff --git a/kaminpar-shm/kaminpar.h b/kaminpar-shm/kaminpar.h
@@ -124,7 +124,6 @@ enum class TwoHopStrategy {
   MATCH_THREADWISE,
   CLUSTER,
   CLUSTER_THREADWISE,
-  LEGACY,
 };
 
 enum class IsolatedNodesClusteringStrategy {

diff --git a/kaminpar-shm/label_propagation.h b/kaminpar-shm/label_propagation.h
@@ -32,6 +32,7 @@
 #include "kaminpar-common/timer.h"
 
 namespace kaminpar {
+
 struct LabelPropagationConfig {
   // Data structures used to accumulate edge weights for gain value calculation
   using RatingMap = ::kaminpar::RatingMap<shm::EdgeWeight, shm::NodeID>;
@@ -2302,4 +2303,5 @@ class OwnedRelaxedTwoLevelClusterWeightVector {
 private:
   TwoLevelClusterWeightVector _cluster_weights;
 };
+
 } // namespace kaminpar