src/main/java/org/apache/aurora/scheduler/async/AsyncModule.java

/**
 * 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 org.apache.aurora.scheduler.async;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;

import javax.inject.Inject;
import javax.inject.Qualifier;
import javax.inject.Singleton;

import com.beust.jcommander.Parameter;
import com.beust.jcommander.Parameters;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.AbstractIdleService;
import com.google.inject.AbstractModule;
import com.google.inject.PrivateModule;

import org.apache.aurora.common.stats.StatsProvider;
import org.apache.aurora.scheduler.SchedulerServicesModule;
import org.apache.aurora.scheduler.base.AsyncUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static java.util.Objects.requireNonNull;

/**
 * Binding module for async task management.
 */
public class AsyncModule extends AbstractModule {
  private static final Logger LOG = LoggerFactory.getLogger(AsyncModule.class);

  @Parameters(separators = "=")
  public static class Options {
    @Parameter(names = "-async_worker_threads",
        description = "The number of worker threads to process async task operations with.")
    public int asyncWorkerThreads = 8;
  }

  private final ScheduledThreadPoolExecutor afterTransaction;

  @Qualifier
  @Target({ FIELD, PARAMETER, METHOD }) @Retention(RUNTIME)
  public @interface AsyncExecutor { }

  public AsyncModule(Options options) {
    // Don't worry about clean shutdown, these can be daemon and cleanup-free.
    // TODO(wfarner): Should we use a bounded caching thread pool executor instead?
    this(AsyncUtil.loggingScheduledExecutor(
        options.asyncWorkerThreads,
        "AsyncProcessor-%d",
        LOG));
  }

  @VisibleForTesting
  public AsyncModule(ScheduledThreadPoolExecutor executor) {
    this.afterTransaction = requireNonNull(executor);
  }

  @Override
  protected void configure() {
    install(new PrivateModule() {
      @Override
      protected void configure() {
        bind(ScheduledThreadPoolExecutor.class).toInstance(afterTransaction);
        bind(RegisterGauges.class).in(Singleton.class);
        expose(RegisterGauges.class);
      }
    });
    SchedulerServicesModule.addAppStartupServiceBinding(binder()).to(RegisterGauges.class);

    bind(Executor.class).annotatedWith(AsyncExecutor.class).toInstance(afterTransaction);
    bind(ScheduledExecutorService.class).annotatedWith(AsyncExecutor.class)
        .toInstance(afterTransaction);
  }

  static class RegisterGauges extends AbstractIdleService {
    @VisibleForTesting
    static final String TIMEOUT_QUEUE_GAUGE = "timeout_queue_size";

    @VisibleForTesting
    static final String ASYNC_TASKS_GAUGE = "async_tasks_completed";

    private final StatsProvider statsProvider;
    private final ScheduledThreadPoolExecutor executor;

    @Inject
    RegisterGauges(StatsProvider statsProvider, ScheduledThreadPoolExecutor executor) {
      this.statsProvider = requireNonNull(statsProvider);
      this.executor = requireNonNull(executor);
    }

    @Override
    protected void startUp() {
      statsProvider.makeGauge(TIMEOUT_QUEUE_GAUGE, () -> executor.getQueue().size());
      statsProvider.makeGauge(ASYNC_TASKS_GAUGE, executor::getCompletedTaskCount);
    }

    @Override
    protected void shutDown() {
      // Nothing to do - await VM shutdown.
    }
  }
}