// Copyright (C) 2012 The Android Open Source Project
//
// 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 com.google.gerrit.server.config;

import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.google.gerrit.server.FanOutExecutor;
import com.google.gerrit.server.git.WorkQueue;
import com.google.inject.AbstractModule;
import com.google.inject.Provides;
import com.google.inject.Singleton;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.eclipse.jgit.lib.Config;

/**
 * Module providing the {@link ReceiveCommitsExecutor}.
 *
 * <p>This module is intended to be installed at the top level when creating a {@code sysInjector}
 * in {@code Daemon} or similar, not nested in another module. This ensures the module can be
 * swapped out for the googlesource.com implementation.
 */
public class SysExecutorModule extends AbstractModule {
  @Override
  protected void configure() {}

  @Provides
  @Singleton
  @ReceiveCommitsExecutor
  public ExecutorService createReceiveCommitsExecutor(
      @GerritServerConfig Config config, WorkQueue queues) {
    int poolSize =
        config.getInt(
            "receive", null, "threadPoolSize", Runtime.getRuntime().availableProcessors());
    return queues.createQueue(poolSize, "ReceiveCommits");
  }

  @Provides
  @Singleton
  @SendEmailExecutor
  public ExecutorService createSendEmailExecutor(
      @GerritServerConfig Config config, WorkQueue queues) {
    int poolSize = config.getInt("sendemail", null, "threadPoolSize", 1);
    if (poolSize == 0) {
      return MoreExecutors.newDirectExecutorService();
    }
    return queues.createQueue(poolSize, "SendEmail");
  }

  @Provides
  @Singleton
  @FanOutExecutor
  public ExecutorService createFanOutExecutor(@GerritServerConfig Config config, WorkQueue queues) {
    int poolSize = config.getInt("execution", null, "fanOutThreadPoolSize", 25);
    if (poolSize == 0) {
      return MoreExecutors.newDirectExecutorService();
    }
    return queues.createQueue(poolSize, "FanOut");
  }

  @Provides
  @Singleton
  @ChangeUpdateExecutor
  public ListeningExecutorService createChangeUpdateExecutor(@GerritServerConfig Config config) {
    int poolSize = config.getInt("receive", null, "changeUpdateThreads", 1);
    if (poolSize <= 1) {
      return MoreExecutors.newDirectExecutorService();
    }
    return MoreExecutors.listeningDecorator(
        MoreExecutors.getExitingExecutorService(
            new ThreadPoolExecutor(
                1,
                poolSize,
                10,
                TimeUnit.MINUTES,
                new ArrayBlockingQueue<Runnable>(poolSize),
                new ThreadFactoryBuilder().setNameFormat("ChangeUpdate-%d").setDaemon(true).build(),
                new ThreadPoolExecutor.CallerRunsPolicy())));
  }
}