content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.thread;
  
  import alluxio.util.ExceptionUtils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.concurrent.atomic.AtomicReference;
  import javax.annotation.Nullable;
  
  /**
   * This thread is able to capture uncaught exceptions from {@code run()}
   * so other classes can check the status of the thread and know why it crashed.
   */
  public class AutopsyThread extends Thread {
    private static final Logger LOG = LoggerFactory.getLogger(AutopsyThread.class);
  
    /** If the thread meets an uncaught exception, this field will be set. */
    private final AtomicReference<Throwable> mThrowable = new AtomicReference<>(null);
  
    /**
     * Constructor.
     */
    public AutopsyThread() {
      setUncaughtExceptionHandler((thread, t) -> {
        onError(t);
      });
    }
  
    /**
     * Checks if the thread has crashed.
     *
     * @return true if the thread crashed due to an uncaught exception
     */
    public boolean crashed() {
      return mThrowable.get() != null;
    }
  
    /**
     * Sets the error before exiting.
     *
     * @param t the crashing error
     */
    public void setError(Throwable t) {
      mThrowable.set(t);
    }
  
    /**
     * Handles the uncaught error on thread crashing.
     * By default, just log the error for further analysis.
     *
     * @param t the crashing error
     */
    public void onError(Throwable t) {
      if (ExceptionUtils.containsInterruptedException(t)) {
        // Tolerate interruption when the master is failing over or closing
        // so we don't extra-crash
        LOG.warn("Thread {} interrupted, assume the master is failing over or shutting down",
            Thread.currentThread().getId());
        return;
      }
      LOG.error("Uncaught exception from thread {}", Thread.currentThread().getId(), t);
      setError(t);
    }
  
    /**
     * Gets the crashing error.
     *
     * @return the error
     */
    @Nullable
    public Throwable getError() {
      return mThrowable.get();
    }
  }
  