geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/rebalance/SatisfyRedundancy.java

/*
 * 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.geode.internal.cache.partitioned.rebalance;

import org.apache.logging.log4j.Logger;

import org.apache.geode.internal.cache.partitioned.rebalance.model.BucketRollup;
import org.apache.geode.internal.cache.partitioned.rebalance.model.Move;
import org.apache.geode.internal.cache.partitioned.rebalance.model.PartitionedRegionLoadModel;
import org.apache.geode.internal.logging.LogService;

/**
 * A director to create redundant copies for buckets that are low in redundancy level. This is most
 * commonly used as an element of the composite director.
 *
 */
public class SatisfyRedundancy extends RebalanceDirectorAdapter {

  private static final Logger logger = LogService.getLogger();

  private PartitionedRegionLoadModel model;


  @Override
  public void initialize(PartitionedRegionLoadModel model) {
    this.model = model;

  }

  @Override
  public void membershipChanged(PartitionedRegionLoadModel model) {
    initialize(model);
  }

  @Override
  public boolean nextStep() {
    if (satisfyRedundancy()) {
      return true;
    } else {
      model.waitForOperations();
      return satisfyRedundancy();
    }
  }

  /**
   * Try to satisfy redundancy for a single bucket.
   *
   * @return true if we actually created a bucket somewhere.
   */
  private boolean satisfyRedundancy() {
    Move bestMove = null;
    BucketRollup first = null;
    while (bestMove == null) {
      if (model.getLowRedundancyBuckets().isEmpty()) {
        return false;
      }

      first = model.getLowRedundancyBuckets().first();
      bestMove = model.findBestTarget(first, true);
      if (bestMove == null && !model.enforceUniqueZones()) {
        bestMove = model.findBestTarget(first, false);
      }
      if (bestMove == null) {
        if (logger.isDebugEnabled()) {
          logger.debug("Skipping low redundancy bucket {} because no member will accept it", first);
        }
        model.ignoreLowRedundancyBucket(first);
      }
    }

    model.createRedundantBucket(first, bestMove.getTarget());

    return true;
  }



}