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/*
 * Copyright © 2017 Cask Data, Inc.
 *
 * 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. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package io.cdap.cdap.internal.app.runtime;

import com.google.common.base.Throwables;
import com.google.common.util.concurrent.Service;
import io.cdap.cdap.app.runtime.ProgramController;
import io.cdap.cdap.common.conf.Constants;
import io.cdap.cdap.common.logging.Loggers;
import io.cdap.cdap.proto.id.ProgramRunId;
import org.apache.twill.common.Threads;
import org.apache.twill.internal.ServiceListenerAdapter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A {@link ProgramController} implementation that control a guava Service.
 * The Service must execute Listeners in the order they were added to the Service, otherwise
 * there may be race conditions if the thread that stops the controller is different than the thread
 * that runs the service. Any Service that extends AbstractService meets this criteria.
 */
public class ProgramControllerServiceAdapter extends AbstractProgramController {

  private static final Logger LOG = LoggerFactory.getLogger(ProgramControllerServiceAdapter.class);
  private static final Logger USER_LOG = Loggers.mdcWrapper(LOG, Constants.Logging.EVENT_TYPE_TAG,
                                                            Constants.Logging.USER_LOG_TAG_VALUE);

  private final Service service;
  private volatile boolean stopRequested;

  public ProgramControllerServiceAdapter(Service service, ProgramRunId programRunId) {
    super(programRunId);
    this.service = service;
    listenToRuntimeState(service);
  }

  @Override
  protected void doSuspend() {
    // no-op
  }

  @Override
  protected void doResume() {
    // no-op
  }

  @Override
  protected void doStop() throws Exception {
    LOG.debug("Stopping controller service for program {}.", getProgramRunId());
    stopRequested = true;
    long gracefulTimeoutMillis = getGracefulTimeoutMillis();
    if (gracefulTimeoutMillis < 0) {
      service.stopAndWait();
    } else {
      gracefulStop(gracefulTimeoutMillis);
    }
    LOG.debug("Controller service for program {} finished running listener hooks.", getProgramRunId());
  }

  /**
   * Requests a graceful shutdown of the service with a timeout. Subclass can override this if it supports
   * graceful termination with timeout.
   */
  protected void gracefulStop(long gracefulTimeoutMillis) {
    service.stopAndWait();
  }

  @Override
  protected void doCommand(String name, Object value) throws Exception {
    // no-op
  }

  private void listenToRuntimeState(Service service) {
    service.addListener(new ServiceListenerAdapter() {
      @Override
      public void running() {
        started();
      }

      @Override
      public void failed(Service.State from, Throwable failure) {
        Throwable rootCause = Throwables.getRootCause(failure);
        LOG.error("{} Program '{}' failed.", getProgramRunId().getType(), getProgramRunId().getProgram(), failure);
        USER_LOG.error("{} program '{}' failed with error: {}. Please check the system logs for more details.",
                       getProgramRunId().getType(), getProgramRunId().getProgram(), rootCause.getMessage(), rootCause);
        error(failure);
      }

      @Override
      public void terminated(Service.State from) {
        if (from != Service.State.STOPPING) {
          // Service completed by itself. Simply signal the state change of this controller.
          complete();
        } else if (!stopRequested) {
          // Otherwise, if the Service was stopped not through this ProgramController.doStop() method,
          // call stop() to transit this controller state to KILLED.
          stop();
        }
      }
    }, Threads.SAME_THREAD_EXECUTOR);
  }
}