com.google.api.ads.common.lib.utils.AdsUtilityRegistry Maven / Gradle / Ivy

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Client library for Java for accessing ads APIs including DFP. If you want to use this library, you must also include another Maven artifact to specify which framework you would like to use it with. For example, to use DFP with Axis, you should include the "dfp-axis" artifact.

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// Copyright 2016 Google Inc. All Rights Reserved.
//
// 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.api.ads.common.lib.utils;

import com.google.common.base.Preconditions;
import com.google.inject.Singleton;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.concurrent.ThreadSafe;

/** A thread-safe registry for usage of {@link AdsUtility ads utilities}. */
@ThreadSafe
@Singleton
public final class AdsUtilityRegistry {

  private volatile Set adsUtilities =
      Collections.newSetFromMap(new ConcurrentHashMap());

  private static final AdsUtilityRegistry INSTANCE = new AdsUtilityRegistry();

  /** Returns the singleton of this class. */
  public static AdsUtilityRegistry getInstance() {
    return INSTANCE;
  }

  // Private constructor to enforce singleton behavior.
  private AdsUtilityRegistry() { }

  /**
   * Adds the specified utility to the registry.
   *
   * Add is performed on a best efforts basis. It is possible that another thread will
   * subsequently remove the utility immediately after the add.
   *
   * @throws NullPointerException if {@code adsUtility == null}
   */
  public void addUtility(final AdsUtility adsUtility) {
    Preconditions.checkNotNull(adsUtility, "Null ads utility");
    adsUtilities.add(adsUtility);
  }

  /** Returns all utilities in the registry and clears the registry. */
  public Set popRegisteredUtilities() {
    // Detach and return, so we don't have to make a copy.
    Set result = Collections.unmodifiableSet(adsUtilities);
    adsUtilities = Collections.newSetFromMap(new ConcurrentHashMap());
    return result;
  }
}