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.testutils.metrics;
  
  import org.apache.beam.sdk.metrics.Distribution;
  import org.apache.beam.sdk.metrics.Metrics;
  import org.apache.beam.sdk.transforms.DoFn;
  
  /**
   * Monitor that records processing time distribution in the pipeline.
   *
   * <p>To use: apply a monitor directly after each source and sink transform. This will capture a
   * distribution of element processing timestamps, which can be collected and queried using {@link
   * org.apache.beam.sdk.testutils.metrics.MetricsReader}.
   */
  public class TimeMonitor<T> extends DoFn<T, T> {
  
    private Distribution timeDistribution;
  
    public TimeMonitor(String namespace, String name) {
      this.timeDistribution = Metrics.distribution(namespace, name);
    }
  
    @ProcessElement
    public void processElement(ProcessContext c) {
      timeDistribution.update(System.currentTimeMillis());
      c.output(c.element());
    }
  }
  