[remove datanode] Load balancing for removing datanode

iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/balancer/region/IDestNodeSelector.java

@@ -0,0 +1,52 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.iotdb.confignode.manager.load.balancer.region;
+
+import org.apache.iotdb.common.rpc.thrift.TConsensusGroupId;
+import org.apache.iotdb.common.rpc.thrift.TDataNodeConfiguration;
+import org.apache.iotdb.common.rpc.thrift.TRegionReplicaSet;
+
+import java.util.List;
+import java.util.Map;
+
+public interface IDestNodeSelector {
+
+  /**
+   * Select the optimal DataNode to place the new replica on along with the remaining replica set.
+   *
+   * @param availableDataNodeMap DataNodes that can be used for allocation
+   * @param freeDiskSpaceMap The free disk space of the DataNodes
+   * @param allocatedRegionGroups Allocated RegionGroups
+   * @param databaseAllocatedRegionGroups Allocated RegionGroups within the same Database with the
+   *     replica set
+   * @param replicationFactor Replication factor of the replica set
+   * @param consensusGroupId TConsensusGroupId of the replica set
+   * @param remainReplicaSet the remaining replica set excluding the removed DataNodes
+   * @return The optimal DataNode to place the new replica on along with the remaining replica set
+   */
+  TDataNodeConfiguration selectDestDataNode(
+      Map<Integer, TDataNodeConfiguration> availableDataNodeMap,
+      Map<Integer, Double> freeDiskSpaceMap,
+      List<TRegionReplicaSet> allocatedRegionGroups,
+      List<TRegionReplicaSet> databaseAllocatedRegionGroups,
+      int replicationFactor,
+      TConsensusGroupId consensusGroupId,
+      TRegionReplicaSet remainReplicaSet);
+}

iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/load/balancer/region/PartiteGraphPlacementDestNodeSelector.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.iotdb.confignode.manager.load.balancer.region;
+
+import org.apache.iotdb.common.rpc.thrift.TConsensusGroupId;
+import org.apache.iotdb.common.rpc.thrift.TDataNodeConfiguration;
+import org.apache.iotdb.common.rpc.thrift.TDataNodeLocation;
+import org.apache.iotdb.common.rpc.thrift.TRegionReplicaSet;
+import org.apache.iotdb.confignode.manager.load.balancer.region.GreedyRegionGroupAllocator.DataNodeEntry;
+
+import org.apache.tsfile.utils.Pair;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.stream.Collectors;
+
+public class PartiteGraphPlacementDestNodeSelector implements IDestNodeSelector {
+  private int replicationFactor;
+
+  private int dataNodeNum;
+  // The number of allocated Regions in each DataNode
+  private int[] regionCounter;
+  // The number of edges in current cluster
+  private int[][] combinationCounter;
+  private Map<Integer, Integer> fakeToRealIdMap;
+  private Map<Integer, Integer> realToFakeIdMap;
+
+  private Set<Integer> remainDataNodesFakeId;
+
+  // Pair<combinationSum, RegionSum>
+  Pair<Integer, Integer> bestValue;
+
+  private Integer targetDataNode = -1;
+
+  @Override
+  public TDataNodeConfiguration selectDestDataNode(
+      Map<Integer, TDataNodeConfiguration> availableDataNodeMap,
+      Map<Integer, Double> freeDiskSpaceMap,
+      List<TRegionReplicaSet> allocatedRegionGroups,
+      List<TRegionReplicaSet> databaseAllocatedRegionGroups,
+      int replicationFactor,
+      TConsensusGroupId consensusGroupId,
+      TRegionReplicaSet remainReplicaSet) {
+    prepare(replicationFactor, availableDataNodeMap, allocatedRegionGroups, remainReplicaSet);
+
+    searchTargetDataNode(freeDiskSpaceMap);
+
+    return availableDataNodeMap.get(fakeToRealIdMap.get(targetDataNode));
+  }
+
+  private void prepare(
+      int replicationFactor,
+      Map<Integer, TDataNodeConfiguration> availableDataNodeMap,
+      List<TRegionReplicaSet> allocatedRegionGroups,
+      TRegionReplicaSet remainReplicaSet) {
+    this.replicationFactor = replicationFactor;
+    this.fakeToRealIdMap = new TreeMap<>();
+    this.realToFakeIdMap = new TreeMap<>();
+    this.dataNodeNum = availableDataNodeMap.size();
+    List<Integer> dataNodeIdList =
+        availableDataNodeMap.values().stream()
+            .map(c -> c.getLocation().getDataNodeId())
+            .collect(Collectors.toList());
+    for (int i = 0; i < dataNodeNum; i++) {
+      fakeToRealIdMap.put(i, dataNodeIdList.get(i));
+      realToFakeIdMap.put(dataNodeIdList.get(i), i);
+    }
+
+    remainDataNodesFakeId =
+        remainReplicaSet.dataNodeLocations.stream()
+            .map(TDataNodeLocation::getDataNodeId)
+            .map(realToFakeIdMap::get)
+            .collect(Collectors.toSet());
+
+    // Compute regionCounter and combinationCounter
+    this.regionCounter = new int[dataNodeNum];
+    Arrays.fill(regionCounter, 0);
+    this.combinationCounter = new int[dataNodeNum][dataNodeNum];
+    for (int i = 0; i < dataNodeNum; i++) {
+      Arrays.fill(combinationCounter[i], 0);
+    }
+    for (TRegionReplicaSet regionReplicaSet : allocatedRegionGroups) {
+      List<TDataNodeLocation> dataNodeLocations = regionReplicaSet.getDataNodeLocations();
+      for (int i = 0; i < dataNodeLocations.size(); i++) {
+        int fakeIId = realToFakeIdMap.get(dataNodeLocations.get(i).getDataNodeId());
+        regionCounter[fakeIId]++;
+        for (int j = i + 1; j < dataNodeLocations.size(); j++) {
+          int fakeJId = realToFakeIdMap.get(dataNodeLocations.get(j).getDataNodeId());
+          combinationCounter[fakeIId][fakeJId] = 1;
+          combinationCounter[fakeJId][fakeIId] = 1;
+        }
+      }
+    }
+
+    this.bestValue = new Pair<>(Integer.MAX_VALUE, Integer.MAX_VALUE);
+  }
+
+  private void searchTargetDataNode(Map<Integer, Double> freeDiskSpaceMap) {
+    List<DataNodeEntry> entryList = new ArrayList<>();
+
+    for (int i = 0; i < dataNodeNum; i++) {
+      if (remainDataNodesFakeId.contains(i)) {
+        continue;
+      }
+      entryList.add(
+          new DataNodeEntry(i, regionCounter[i], freeDiskSpaceMap.get(fakeToRealIdMap.get(i))));
+    }
+    Collections.sort(entryList);
+
+    int[] alternativeReplica = new int[replicationFactor];
+
+    int pos = 0;
+    for (Integer integer : remainDataNodesFakeId) {
+      if (pos >= replicationFactor) {
+        break;
+      }
+      alternativeReplica[pos] = integer;
+      pos++;
+    }
+
+    double minFreeDiskSpace = entryList.get(0).freeDiskSpace;
+    for (DataNodeEntry dataNodeEntry : entryList) {
+      if (dataNodeEntry.freeDiskSpace > minFreeDiskSpace) {
+        break;
+      }
+      alternativeReplica[replicationFactor - 1] = dataNodeEntry.dataNodeId;
+      Pair<Integer, Integer> currentValue = valuation(alternativeReplica);
+      if (currentValue.left < bestValue.left
+          || (currentValue.left.equals(bestValue.left) && currentValue.right < bestValue.right)) {
+        bestValue = currentValue;
+        targetDataNode = dataNodeEntry.dataNodeId;
+      }
+    }
+  }
+
+  private Pair<Integer, Integer> valuation(int[] nodes) {
+    int edgeSum = 0;
+    int regionSum = 0;
+    for (int iota : nodes) {
+      for (int kappa : nodes) {
+        edgeSum += combinationCounter[iota][kappa];
+      }
+      regionSum += regionCounter[iota];
+    }
+    return new Pair<>(edgeSum, regionSum);
+  }
+}