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.runners.dataflow.worker.status;
  
  import java.io.PrintWriter;
  import java.util.concurrent.atomic.AtomicReference;
  
  /** Capture the last exception thrown during processing, and display that on the statusz page. */
  public class LastExceptionDataProvider implements StatusDataProvider {
  
    private static final AtomicReference<Throwable> lastException = new AtomicReference<>();
  
    /** Report an exception to the exception data provider. */
    public static void reportException(Throwable t) {
      lastException.set(t);
    }
  
    @Override
    public void appendSummaryHtml(PrintWriter writer) {
      Throwable t = lastException.get();
      if (t == null) {
        writer.println("None<br>");
      } else {
        writer.println("<pre>");
        t.printStackTrace(writer);
        writer.println("</pre>");
      }
    }
  }
  