/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.channel.socket.nio;
  
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  import org.jboss.netty.util.ExternalResourceReleasable;
  import org.jboss.netty.util.internal.ExecutorUtil;
  
  import java.util.concurrent.Executor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  
  public abstract class AbstractNioBossPool<E extends Boss>
          implements BossPool<E>, ExternalResourceReleasable {
  
      /**
       * The boss pool raises an exception unless all boss threads start and run within this timeout (in seconds.)
       */
      private static final int INITIALIZATION_TIMEOUT = 10;
  
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(AbstractNioBossPool.class);
  
      private final Boss[] bosses;
      private final AtomicInteger bossIndex = new AtomicInteger();
      private final Executor bossExecutor;
      private final AtomicBoolean initialized = new AtomicBoolean(false);
  
      /**
       * Create a new instance
       *
       * @param bossExecutor the {@link Executor} to use for the {@link Boss}'s
       * @param bossCount the count of {@link Boss}'s to create
       */
      AbstractNioBossPool(Executor bossExecutor, int bossCount) {
          this(bossExecutor, bossCount, true);
      }
  
      AbstractNioBossPool(Executor bossExecutor, int bossCount, boolean autoInit) {
          if (bossExecutor == null) {
              throw new NullPointerException("bossExecutor");
          }
          if (bossCount <= 0) {
              throw new IllegalArgumentException(
                      "bossCount (" + bossCount + ") " +
                              "must be a positive integer.");
          }
          bosses = new Boss[bossCount];
          this.bossExecutor = bossExecutor;
          if (autoInit) {
              init();
          }
      }
  
      protected void init() {
          if (!initialized.compareAndSet(false, true)) {
              throw new IllegalStateException("initialized already");
          }
  
          for (int i = 0; i < bosses.length; i++) {
              bosses[i] = newBoss(bossExecutor);
          }
  
          waitForBossThreads();
      }
  
      private void waitForBossThreads() {
          long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(INITIALIZATION_TIMEOUT);
          boolean warn = false;
          for (Boss boss: bosses) {
              if (!(boss instanceof AbstractNioSelector)) {
                  continue;
              }
  
              AbstractNioSelector selector = (AbstractNioSelector) boss;
              long waitTime = deadline - System.nanoTime();
              try {
                  if (waitTime <= 0) {
                      if (selector.thread == null) {
                          warn = true;
                          break;
                      }
                  } else if (!selector.startupLatch.await(waitTime, TimeUnit.NANOSECONDS)) {
                      warn = true;
                      break;
                 }
             } catch (InterruptedException ignore) {
                 // Stop waiting for the boss threads and let someone else take care of the interruption.
                 Thread.currentThread().interrupt();
                 break;
             }
         }
 
         if (warn) {
             logger.warn(
                     "Failed to get all boss threads ready within " + INITIALIZATION_TIMEOUT + " second(s). " +
                     "Make sure to specify the executor which has more threads than the requested bossCount. " +
                     "If unsure, use Executors.newCachedThreadPool().");
         }
     }
 
     /**
      * Create a new {@link Boss} which uses the given {@link Executor} to service IO
      *
      *
      * @param executor the {@link Executor} to use
      * @return worker the new {@link Boss}
      */
     protected abstract E newBoss(Executor executor);
 
     @SuppressWarnings("unchecked")
     public E nextBoss() {
         return (E) bosses[Math.abs(bossIndex.getAndIncrement() % bosses.length)];
     }
 
     public void rebuildSelectors() {
         for (Boss boss: bosses) {
             boss.rebuildSelector();
         }
     }
 
     public void releaseExternalResources() {
         shutdown();
         ExecutorUtil.shutdownNow(bossExecutor);
     }
 
     public void shutdown() {
         for (Boss boss: bosses) {
             boss.shutdown();
         }
     }
 }