content: /*
   * 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 org.apache.beam.sdk.metrics;
  
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Joiner;
  
  /** Standard {@link org.apache.beam.sdk.io.Source} Metrics. */
  public class SourceMetrics {
  
    private static final String SOURCE_NAMESPACE = "source";
    private static final String SOURCE_SPLITS_NAMESPACE = "source.splits";
    private static final String SEPARATOR = ".";
  
    private static final String ELEMENTS_READ = "elements_read";
    private static final String BYTES_READ = "bytes_read";
    private static final String BACKLOG_BYTES = "backlog_bytes";
    private static final String BACKLOG_ELEMENTS = "backlog_elements";
  
    private static final Counter ELEMENTS_READ_COUNTER =
        Metrics.counter(SOURCE_NAMESPACE, ELEMENTS_READ);
    private static final Counter BYTES_READ_COUNTER = Metrics.counter(SOURCE_NAMESPACE, BYTES_READ);
    private static final Gauge BACKLOG_BYTES_GAUGE = Metrics.gauge(SOURCE_NAMESPACE, BACKLOG_BYTES);
    private static final Gauge BACKLOG_ELEMENTS_GAUGE =
        Metrics.gauge(SOURCE_NAMESPACE, BACKLOG_ELEMENTS);
  
    /** Counter of elements read by a source. */
    public static Counter elementsRead() {
      return ELEMENTS_READ_COUNTER;
    }
  
    /**
     * Counter of elements read by a source split.
     *
     * <p>Should only be used when there is a small, fixed set of split IDs so as not to overload
     * metrics backends.
     */
    public static Counter elementsReadBySplit(String splitId) {
      return Metrics.counter(SOURCE_SPLITS_NAMESPACE, renderName(splitId, ELEMENTS_READ));
    }
  
    /** Counter of bytes read by a source. */
    public static Counter bytesRead() {
      return BYTES_READ_COUNTER;
    }
  
    /**
     * Counter of bytes read by a source split.
     *
     * <p>Should only be used when there is a small, fixed set of split IDs so as not to overload
     * metrics backends.
     */
    public static Counter bytesReadBySplit(String splitId) {
      return Metrics.counter(SOURCE_SPLITS_NAMESPACE, renderName(splitId, BYTES_READ));
    }
  
    /** Gauge for source backlog in bytes. */
    public static Gauge backlogBytes() {
      return BACKLOG_BYTES_GAUGE;
    }
  
    /**
     * Gauge for source split backlog in bytes.
     *
     * <p>Should only be used when there is a small, fixed set of split IDs so as not to overload
     * metrics backends.
     */
    public static Gauge backlogBytesOfSplit(String splitId) {
      return Metrics.gauge(SOURCE_SPLITS_NAMESPACE, renderName(splitId, BACKLOG_BYTES));
    }
  
    /** Gauge for source backlog in elements. */
    public static Gauge backlogElements() {
      return BACKLOG_ELEMENTS_GAUGE;
    }
  
    /**
     * Gauge for source split backlog in elements.
     *
     * <p>Should only be used when there is a small, fixed set of split IDs so as not to overload
     * metrics backends.
     */
    public static Gauge backlogElementsOfSplit(String splitId) {
      return Metrics.gauge(SOURCE_SPLITS_NAMESPACE, renderName(splitId, BACKLOG_ELEMENTS));
    }
  
    private static String renderName(String... nameParts) {
      return Joiner.on(SEPARATOR).join(nameParts);
    }
  }
  