webindex/modules/core/src/main/java/webindex/core/models/UriInfo.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 webindex.core.models;

import java.io.Serializable;
import java.util.Optional;

import com.google.common.base.Preconditions;

/**
 * Used by URI collision free map
 */
public class UriInfo implements Serializable {

  private static final long serialVersionUID = 1L;

  public static final UriInfo ZERO = new UriInfo(0, 0);

  // the numbers of documents that link to this URI
  public long linksTo;

  // the number of documents with this URI. Should be 0 or 1
  public int docs;

  public UriInfo() {}

  public UriInfo(long linksTo, int docs) {
    this.linksTo = linksTo;
    this.docs = docs;
  }

  public void add(UriInfo other) {
    Preconditions.checkArgument(this != ZERO);
    this.linksTo += other.linksTo;
    this.docs += other.docs;
  }

  @Override
  public String toString() {
    return linksTo + " " + docs;
  }

  @Override
  public boolean equals(Object o) {
    if (o instanceof UriInfo) {
      UriInfo oui = (UriInfo) o;
      return linksTo == oui.linksTo && docs == oui.docs;
    }
    return false;
  }

  @Override
  public int hashCode() {
    return docs + (int) linksTo;
  }

  public static UriInfo merge(UriInfo u1, UriInfo u2) {
    UriInfo total = new UriInfo(0, 0);
    total.add(u1);
    total.add(u2);
    return total;
  }

  public static Optional<UriInfo> reduce(Iterable<UriInfo> uriInfos) {
    UriInfo sum = new UriInfo();
    for (UriInfo uriInfo : uriInfos) {
      sum.add(uriInfo);
    }
    return sum.equals(ZERO) ? Optional.empty() : Optional.of(sum);
  }
}