content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * 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
   *
   * https://opensource.org/licenses/Apache-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.tencent.angel.utils;
  
  import io.netty.buffer.PooledByteBufAllocator;
  import io.netty.util.internal.PlatformDependent;
  
  import java.lang.reflect.Field;
  
  public class NettyUtils {
    public static PooledByteBufAllocator createPooledByteBufAllocator(boolean allowDirectBufs,
      boolean allowCache, int numCores) {
      if (numCores == 0) {
        numCores = Runtime.getRuntime().availableProcessors();
      }
      return new PooledByteBufAllocator(allowDirectBufs && PlatformDependent.directBufferPreferred(),
        Math.min(getPrivateStaticField("DEFAULT_NUM_HEAP_ARENA"), numCores),
        Math.min(getPrivateStaticField("DEFAULT_NUM_DIRECT_ARENA"), allowDirectBufs ? numCores : 0),
        getPrivateStaticField("DEFAULT_PAGE_SIZE"), getPrivateStaticField("DEFAULT_MAX_ORDER"),
        allowCache ? getPrivateStaticField("DEFAULT_TINY_CACHE_SIZE") : 0,
        allowCache ? getPrivateStaticField("DEFAULT_SMALL_CACHE_SIZE") : 0,
        allowCache ? getPrivateStaticField("DEFAULT_NORMAL_CACHE_SIZE") : 0);
    }
  
    private static int getPrivateStaticField(String name) {
      try {
        Field f = PooledByteBufAllocator.DEFAULT.getClass().getDeclaredField(name);
        f.setAccessible(true);
        return f.getInt(null);
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
  }
  