java/com/google/gerrit/server/logging/MutableTags.java

// Copyright (C) 2018 The Android Open Source Project
//
// 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.

package com.google.gerrit.server.logging;

import static java.util.Objects.requireNonNull;

import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.SetMultimap;
import com.google.common.flogger.backend.Tags;

public class MutableTags {
  private final SetMultimap<String, String> tagMap =
      MultimapBuilder.hashKeys().hashSetValues().build();
  private Tags tags = Tags.empty();

  public Tags getTags() {
    return tags;
  }

  /**
   * Adds a tag if a tag with the same name and value doesn't exist yet.
   *
   * @param name the name of the tag
   * @param value the value of the tag
   * @return {@code true} if the tag was added, {@code false} if the tag was not added because it
   *     already exists
   */
  public boolean add(String name, String value) {
    requireNonNull(name, "tag name is required");
    requireNonNull(value, "tag value is required");
    boolean ret = tagMap.put(name, value);
    if (ret) {
      buildTags();
    }
    return ret;
  }

  /**
   * Removes the tag with the given name and value.
   *
   * @param name the name of the tag
   * @param value the value of the tag
   */
  public void remove(String name, String value) {
    requireNonNull(name, "tag name is required");
    requireNonNull(value, "tag value is required");
    if (tagMap.remove(name, value)) {
      buildTags();
    }
  }

  /**
   * Checks if the contained tag map is empty.
   *
   * @return {@code true} if there are no tags, otherwise {@code false}
   */
  public boolean isEmpty() {
    return tagMap.isEmpty();
  }

  /** Clears all tags. */
  public void clear() {
    tagMap.clear();
    tags = Tags.empty();
  }

  /**
   * Returns the tags as Multimap.
   *
   * @return the tags as Multimap
   */
  public ImmutableSetMultimap<String, String> asMap() {
    return ImmutableSetMultimap.copyOf(tagMap);
  }

  /**
   * Replaces the existing tags with the provided tags.
   *
   * @param tags the tags that should be set.
   */
  void set(ImmutableSetMultimap<String, String> tags) {
    tagMap.clear();
    tags.forEach(tagMap::put);
    buildTags();
  }

  private void buildTags() {
    if (tagMap.isEmpty()) {
      if (tags.isEmpty()) {
        return;
      }
      tags = Tags.empty();
      return;
    }

    Tags.Builder tagsBuilder = Tags.builder();
    tagMap.forEach(tagsBuilder::addTag);
    tags = tagsBuilder.build();
  }

  @Override
  public String toString() {
    buildTags();
    return MoreObjects.toStringHelper(this).add("tags", tags).toString();
  }
}