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/*
 * Copyright © 2021-present Arcade Data Ltd ([email protected])
 *
 * Licensed 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.
 *
 * SPDX-FileCopyrightText: 2021-present Arcade Data Ltd ([email protected])
 * SPDX-License-Identifier: Apache-2.0
 */
package com.arcadedb.database.bucketselectionstrategy;

import com.arcadedb.database.Document;
import com.arcadedb.schema.LocalDocumentType;

/**
 * Default round-robin implementation that uses all the available buckets. For async execution, the thread selection strategy is used.
 *
 * @author Luca Garulli
 */
public class RoundRobinBucketSelectionStrategy extends ThreadBucketSelectionStrategy {
  public static final String NAME    = "round-robin";
  private volatile    int    current = -1;

  @Override
  public BucketSelectionStrategy copy() {
    final RoundRobinBucketSelectionStrategy copy = new RoundRobinBucketSelectionStrategy();
    copy.total = total;
    copy.current = current;
    return copy;
  }

  @Override
  public void setType(final LocalDocumentType type) {
    this.total = type.getBuckets(false).size();
    synchronized (this) {
      if (current >= total)
        // RESET IT
        current = -1;
    }
  }

  @Override
  public int getBucketIdByRecord(final Document record, final boolean async) {
    if (async)
      return super.getBucketIdByRecord(record, async);

    synchronized (this) {
      // COPY THE VALUE ON THE HEAP FOR MULTI-THREAD ACCESS
      int bucketIndex = ++current;
      if (bucketIndex >= total) {
        current = 0;
        bucketIndex = 0;
      }
      return bucketIndex;
    }
  }

  @Override
  public String getName() {
    return NAME;
  }
}