/*
    * 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.internal.SystemPropertyUtil;
  
  import java.io.IOException;
  import java.nio.channels.CancelledKeyException;
  import java.nio.channels.Selector;
  import java.util.concurrent.TimeUnit;
  
  final class SelectorUtil {
      private static final InternalLogger logger =
          InternalLoggerFactory.getInstance(SelectorUtil.class);
  
      static final int DEFAULT_IO_THREADS = Runtime.getRuntime().availableProcessors() * 2;
      static final long DEFAULT_SELECT_TIMEOUT = 500;
      static final long SELECT_TIMEOUT =
              SystemPropertyUtil.getLong("org.jboss.netty.selectTimeout", DEFAULT_SELECT_TIMEOUT);
      static final long SELECT_TIMEOUT_NANOS = TimeUnit.MILLISECONDS.toNanos(SELECT_TIMEOUT);
      static final boolean EPOLL_BUG_WORKAROUND =
              SystemPropertyUtil.getBoolean("org.jboss.netty.epollBugWorkaround", false);
  
      // Workaround for JDK NIO bug.
      //
      // See:
      // - http://bugs.sun.com/view_bug.do?bug_id=6427854
      // - https://github.com/netty/netty/issues/203
      static {
          String key = "sun.nio.ch.bugLevel";
          try {
              String buglevel = System.getProperty(key);
              if (buglevel == null) {
                  System.setProperty(key, "");
              }
          } catch (SecurityException e) {
              if (logger.isDebugEnabled()) {
                  logger.debug("Unable to get/set System Property '" + key + '\'', e);
              }
          }
          if (logger.isDebugEnabled()) {
              logger.debug("Using select timeout of " + SELECT_TIMEOUT);
              logger.debug("Epoll-bug workaround enabled = " + EPOLL_BUG_WORKAROUND);
          }
      }
  
      static Selector open() throws IOException {
          return Selector.open();
      }
  
      static int select(Selector selector) throws IOException {
          try {
              return selector.select(SELECT_TIMEOUT);
          } catch (CancelledKeyException e) {
              if (logger.isDebugEnabled()) {
                  logger.debug(
                          CancelledKeyException.class.getSimpleName() +
                          " raised by a Selector - JDK bug?", e);
              }
              // Harmless exception - log anyway
          }
          return -1;
      }
  
      private SelectorUtil() {
          // Unused
      }
  }