xmemcached/src/main/java/com/google/code/yanf4j/util/SystemUtils.java

/**
 * Copyright [2009-2010] [dennis zhuang(killme2008@gmail.com)] 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
 */
/**
 * Copyright [2009-2010] [dennis zhuang(killme2008@gmail.com)] 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.code.yanf4j.util;

import java.io.IOException;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.Selector;
import java.nio.channels.spi.SelectorProvider;
import java.util.Queue;
import java.util.Random;

/**
 * System utils
 * 
 * @author dennis
 * 
 */
public final class SystemUtils {

  private SystemUtils() {

  }

  public static final String OS_NAME = System.getProperty("os.name");

  private static boolean isLinuxPlatform = false;

  static {
    if (OS_NAME != null && OS_NAME.toLowerCase().indexOf("linux") >= 0) {
      isLinuxPlatform = true;
    }
  }
  public static final String JAVA_VERSION = System.getProperty("java.version");
  private static boolean isAfterJava6u4Version = false;
  static {
    if (JAVA_VERSION != null) {
      // java4 or java5
      if (JAVA_VERSION.indexOf("1.4.") >= 0 || JAVA_VERSION.indexOf("1.5.") >= 0) {
        isAfterJava6u4Version = false;
      } else if (JAVA_VERSION.indexOf("1.6.") >= 0) {
        int index = JAVA_VERSION.indexOf("_");
        if (index > 0) {
          String subVersionStr = JAVA_VERSION.substring(index + 1);
          if (subVersionStr != null && subVersionStr.length() > 0) {
            try {
              int subVersion = Integer.parseInt(subVersionStr);
              if (subVersion >= 4) {
                isAfterJava6u4Version = true;
              }
            } catch (NumberFormatException e) {

            }
          }
        }
        // after java6
      } else {
        isAfterJava6u4Version = true;
      }
    }
  }

  public static final boolean isLinuxPlatform() {
    return isLinuxPlatform;
  }

  public static final boolean isAfterJava6u4Version() {
    return isAfterJava6u4Version;
  }

  public static void main(String[] args) {
    System.out.println(isAfterJava6u4Version());
  }

  public static final int getSystemThreadCount() {
    int cpus = getCpuProcessorCount();
    if (cpus <= 8) {
      return cpus;
    } else {
      return 8 + (cpus - 8) * 5 / 8;
    }
  }

  public static final int getCpuProcessorCount() {
    return Runtime.getRuntime().availableProcessors();
  }

  public static final Selector openSelector() throws IOException {
    Selector result = null;
    // check if it is linux os
    if (SystemUtils.isLinuxPlatform()) {
      try {
        Class<?> providerClazz = Class.forName("sun.nio.ch.EPollSelectorProvider");
        if (providerClazz != null) {
          try {
            Method method = providerClazz.getMethod("provider");
            if (method != null) {
              SelectorProvider selectorProvider = (SelectorProvider) method.invoke(null);
              if (selectorProvider != null) {
                result = selectorProvider.openSelector();
              }
            }
          } catch (Exception e) {
            // ignore
          }
        }
      } catch (Exception e) {
        // ignore
      }
    }
    if (result == null) {
      result = Selector.open();
    }
    return result;

  }

  public static final String getRawAddress(InetSocketAddress inetSocketAddress) {
    InetAddress address = inetSocketAddress.getAddress();
    return address != null ? address.getHostAddress() : inetSocketAddress.getHostName();
  }

  public static final Queue<?> createTransferQueue() {
    try {
      return (Queue<?>) Class.forName("java.util.concurrent.LinkedTransferQueue").newInstance();
    } catch (Exception e) {
      return new LinkedTransferQueue<Object>();
    }
  }

  public static Random createRandom() {
    return new Random();
  }
}