gobblin.metrics.GobblinMetricsRegistry Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of gobblin-core Show documentation
Gobblin Ingestion Framework
There is a newer version: 0.8.0
/*
 * Copyright (C) 2014-2016 LinkedIn Corp. 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.
 */

package gobblin.metrics;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;

import com.google.common.base.Optional;
import com.google.common.base.Throwables;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;


/**
 * Registry that stores instances of {@link GobblinMetrics} identified by an arbitrary string id. The static method
 * {@link #getInstance()} provides a static instance of this this class that should be considered the global registry of
 * metrics.
 *
 * 
 *   An application could also instantiate one or more registries to, for example, separate instances of
 *   {@link GobblinMetrics} into different scopes.
 * 
 */
public class GobblinMetricsRegistry {

  private static final GobblinMetricsRegistry GLOBAL_INSTANCE = new GobblinMetricsRegistry();

  private final Cache metricsCache = CacheBuilder.newBuilder().softValues().build();

  private GobblinMetricsRegistry() {
    // Do nothing
  }

  /**
   * Associate a {@link GobblinMetrics} instance with a given ID if the ID is
   * not already associated with a {@link GobblinMetrics} instance.
   *
   * @param id the given {@link GobblinMetrics} ID
   * @param gobblinMetrics the {@link GobblinMetrics} instance to be associated with the given ID
   * @return the previous {@link GobblinMetrics} instance associated with the ID or {@code null}
   *         if there's no previous {@link GobblinMetrics} instance associated with the ID
   */
  public GobblinMetrics putIfAbsent(String id, GobblinMetrics gobblinMetrics) {
    return this.metricsCache.asMap().putIfAbsent(id, gobblinMetrics);
  }

  /**
   * Get the {@link GobblinMetrics} instance associated with a given ID.
   *
   * @param id the given {@link GobblinMetrics} ID
   * @return the {@link GobblinMetrics} instance associated with the ID, wrapped in an {@link Optional} or
   *         {@link Optional#absent()} if no {@link GobblinMetrics} instance for the given ID is found
   */
  public Optional get(String id) {
    return Optional.fromNullable(this.metricsCache.getIfPresent(id));
  }

  /**
   * Get the {@link GobblinMetrics} instance associated with a given ID. If the ID is not found this method returns the
   * {@link GobblinMetrics} returned by the given {@link Callable}, and creates a mapping between the specified ID
   * and the {@link GobblinMetrics} instance returned by the {@link Callable}.
   *
   * @param id the given {@link GobblinMetrics} ID
   * @param valueLoader a {@link Callable} that returns a {@link GobblinMetrics}, the {@link Callable} is only invoked
   *                    if the given id is not found
   *
   * @return a {@link GobblinMetrics} instance associated with the id
   */
  public GobblinMetrics getOrDefault(String id, Callable valueLoader) {
    try {
      return this.metricsCache.get(id, valueLoader);
    } catch (ExecutionException ee) {
      throw Throwables.propagate(ee);
    }
  }

  /**
   * Remove the {@link GobblinMetrics} instance with a given ID.
   *
   * @param id the given {@link GobblinMetrics} ID
   * @return removed {@link GobblinMetrics} instance or {@code null} if no
   *         {@link GobblinMetrics} instance for the given ID is found
   */
  public GobblinMetrics remove(String id) {
    return this.metricsCache.asMap().remove(id);
  }

  /**
   * Get an instance of {@link GobblinMetricsRegistry}.
   *
   * @return an instance of {@link GobblinMetricsRegistry}
   */
  public static GobblinMetricsRegistry getInstance() {
    return GLOBAL_INSTANCE;
  }
}