Merge pull request #9463 from vnickolov/articulation-points

articulation points

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPoints.java

@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import com.carrotsearch.hppc.BitSet;
+import org.neo4j.gds.Algorithm;
+import org.neo4j.gds.api.Graph;
+import org.neo4j.gds.collections.ha.HugeLongArray;
+import org.neo4j.gds.collections.ha.HugeObjectArray;
+import org.neo4j.gds.core.utils.progress.tasks.ProgressTracker;
+
+public class ArticulationPoints extends Algorithm<BitSet> {
+    private final Graph graph;
+
+    private final BitSet visited;
+    private final HugeLongArray tin;
+    private final HugeLongArray low;
+    private final HugeLongArray children;
+    private long timer;
+    private long stackIndex = -1;
+
+    private final BitSet articulationPoints;
+
+    public ArticulationPoints(Graph graph, ProgressTracker progressTracker) {
+        super(progressTracker);
+
+        this.graph = graph;
+
+        this.visited = new BitSet(graph.nodeCount());
+        this.tin = HugeLongArray.newArray(graph.nodeCount());
+        this.low = HugeLongArray.newArray(graph.nodeCount());
+        this.children = HugeLongArray.newArray(graph.nodeCount());
+
+        this.articulationPoints = new BitSet(graph.nodeCount());
+    }
+
+    @Override
+    public BitSet compute() {
+        timer = 0;
+        visited.clear();
+        tin.setAll(__ -> -1);
+        low.setAll(__ -> -1);
+        progressTracker.beginSubTask("ArticulationPoints");
+        //each edge may have at most one event to the stack at the same time
+        var stack = HugeObjectArray.newArray(StackEvent.class, graph.relationshipCount());
+
+        var n = graph.nodeCount();
+        for (int i = 0; i < n; ++i) {
+            if (!visited.get(i)) {
+                dfs(i, stack);
+            }
+        }
+        progressTracker.endSubTask("ArticulationPoints");
+        return this.articulationPoints;
+    }
+
+    private void dfs(long node, HugeObjectArray<StackEvent> stack) {
+        stack.set(++stackIndex, StackEvent.upcomingVisit(node,-1));
+        while (stackIndex >= 0) {
+            var stackEvent = stack.get(stackIndex--);
+            visitEvent(stackEvent, stack);
+        }
+        if (children.get(node) > 1) {
+            articulationPoints.set(node);
+        } else {
+            articulationPoints.clear(node);
+        }
+        progressTracker.logProgress();
+    }
+
+    private void visitEvent(StackEvent event, HugeObjectArray<StackEvent> stack) {
+        if (event.lastVisit()) {
+            var to = event.eventNode();
+            var v = event.triggerNode();
+            var lowV = low.get(v);
+            var lowTo = low.get(to);
+            low.set(v, Math.min(lowV, lowTo));
+            var tinV = tin.get(v);
+            if (lowTo >= tinV) {
+                articulationPoints.set(v);
+            }
+            children.addTo(v, 1);
+            progressTracker.logProgress();
+            return;
+        }
+
+        if (!visited.get(event.eventNode())) {
+            var v = event.eventNode();
+            visited.set(v);
+            children.set(v, 0);
+            var p = event.triggerNode();
+            tin.set(v, timer);
+            low.set(v, timer++);
+            ///add post event (Should be before everything)
+            if (p != -1) {
+                stack.set(++stackIndex, StackEvent.lastVisit(v, p));
+            }
+            graph.forEachRelationship(v, (s, to) -> {
+                if (to == p) {
+                    return true;
+                }
+                stack.set(++stackIndex,  StackEvent.upcomingVisit(to, v));
+
+                return true;
+            });
+
+        } else {
+            long v = event.triggerNode();
+            long to = event.eventNode();
+            var lowV = low.get(v);
+            var tinTo = tin.get(to);
+            low.set(v, Math.min(lowV, tinTo));
+        }
+    }
+
+
+    record StackEvent(long eventNode, long triggerNode, boolean lastVisit) {
+        static StackEvent upcomingVisit(long node, long triggerNode) {
+            return new StackEvent(node, triggerNode, false);
+        }
+
+        static StackEvent lastVisit(long node, long triggerNode) {
+            return new StackEvent(node, triggerNode, true);
+        }
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsBaseConfig.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.NodeLabel;
+import org.neo4j.gds.RelationshipType;
+import org.neo4j.gds.annotation.Configuration;
+import org.neo4j.gds.api.GraphStore;
+import org.neo4j.gds.config.AlgoBaseConfig;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.neo4j.gds.utils.StringFormatting.formatWithLocale;
+
+public interface ArticulationPointsBaseConfig extends AlgoBaseConfig {
+
+    @Configuration.GraphStoreValidationCheck
+    default void requireUndirectedGraph(
+        GraphStore graphStore,
+        Collection<NodeLabel> ignored,
+        Collection<RelationshipType> selectedRelationshipTypes
+    ) {
+        if (!graphStore.schema().filterRelationshipTypes(Set.copyOf(selectedRelationshipTypes)).isUndirected()) {
+            throw new IllegalArgumentException(formatWithLocale(
+                "Articulation Points algorithm requires relationship projections to be UNDIRECTED. " +
+                    "Selected relationships `%s` are not all undirected.",
+                selectedRelationshipTypes.stream().map(RelationshipType::name).collect(Collectors.toSet())
+            ));
+        }
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsMemoryEstimateDefinition.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.bridges.Bridges;
+import org.neo4j.gds.collections.ha.HugeLongArray;
+import org.neo4j.gds.collections.ha.HugeObjectArray;
+import org.neo4j.gds.mem.Estimate;
+import org.neo4j.gds.mem.MemoryEstimateDefinition;
+import org.neo4j.gds.mem.MemoryEstimation;
+import org.neo4j.gds.mem.MemoryEstimations;
+import org.neo4j.gds.mem.MemoryRange;
+
+public class ArticulationPointsMemoryEstimateDefinition implements MemoryEstimateDefinition {
+    @Override
+    public MemoryEstimation memoryEstimation() {
+
+        var builder = MemoryEstimations.builder(Bridges.class);
+        builder
+            .perNode("tin", HugeLongArray::memoryEstimation)
+            .perNode("low", HugeLongArray::memoryEstimation)
+            .perNode("children", HugeLongArray::memoryEstimation)
+            .perNode("visited", Estimate::sizeOfBitset)
+            .perNode("articulationPoints", Estimate::sizeOfBitset);
+
+        builder.rangePerGraphDimension("stack", ((graphDimensions, concurrency) -> {
+            long relationshipCount = graphDimensions.relCountUpperBound();
+            return MemoryRange.of(
+                HugeObjectArray.memoryEstimation(relationshipCount, Estimate.sizeOfInstance(ArticulationPoints.StackEvent.class))
+            );
+
+
+        }));
+
+        return builder.build();
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsMutateConfig.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.annotation.Configuration;
+import org.neo4j.gds.config.MutateNodePropertyConfig;
+import org.neo4j.gds.core.CypherMapWrapper;
+
+import java.util.Map;
+
+@Configuration
+public interface ArticulationPointsMutateConfig extends ArticulationPointsBaseConfig, MutateNodePropertyConfig {
+    static ArticulationPointsMutateConfig of(CypherMapWrapper cypherMapWrapper) {
+        return new ArticulationPointsMutateConfigImpl(cypherMapWrapper);
+    }
+
+    static ArticulationPointsMutateConfig of(Map<String, Object> rawMapConfiguration) {
+        return of(CypherMapWrapper.create(rawMapConfiguration));
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsProgressTaskCreator.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.core.utils.progress.tasks.Task;
+import org.neo4j.gds.core.utils.progress.tasks.Tasks;
+
+public final class ArticulationPointsProgressTaskCreator {
+
+    private ArticulationPointsProgressTaskCreator() {}
+
+    public static Task progressTask(long nodeCount) {
+        return Tasks.leaf("ArticulationPoints", nodeCount);
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsStatsConfig.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.annotation.Configuration;
+import org.neo4j.gds.core.CypherMapWrapper;
+
+import java.util.Map;
+
+@Configuration
+public interface ArticulationPointsStatsConfig extends ArticulationPointsBaseConfig {
+    static ArticulationPointsStatsConfig of(CypherMapWrapper cypherMapWrapper) {
+        return new ArticulationPointsStatsConfigImpl(cypherMapWrapper);
+    }
+
+    static ArticulationPointsStatsConfig of(Map<String, Object> rawMapConfiguration) {
+        return of(CypherMapWrapper.create(rawMapConfiguration));
+    }
+}

algo/src/main/java/org/neo4j/gds/articulationpoints/ArticulationPointsStreamConfig.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gds.articulationpoints;
+
+import org.neo4j.gds.annotation.Configuration;
+import org.neo4j.gds.core.CypherMapWrapper;
+
+import java.util.Map;
+
+@Configuration
+public interface ArticulationPointsStreamConfig extends ArticulationPointsBaseConfig {
+    static ArticulationPointsStreamConfig of(CypherMapWrapper cypherMapWrapper) {
+        return new ArticulationPointsStreamConfigImpl(cypherMapWrapper);
+    }
+
+    static ArticulationPointsStreamConfig of(Map<String, Object> rawMapConfiguration) {
+        return of(CypherMapWrapper.create(rawMapConfiguration));
+    }
+}