content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF 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.apache.cassandra.utils;
  
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.UnknownHostException;
  import java.nio.ByteBuffer;
  
  import org.github.jamm.MemoryMeter;
  import org.github.jamm.MemoryMeter.ByteBufferMode;
  import org.github.jamm.MemoryMeter.Guess;
  
  import static org.github.jamm.MemoryMeterStrategy.MEMORY_LAYOUT;
  import static org.github.jamm.utils.ArrayMeasurementUtils.computeArraySize;
  
  /**
   * A convenience class for wrapping access to MemoryMeter. Should be used instead of using a {@code MemoryMeter} directly.
   * {@code MemoryMeter} can be used directly for testing as it allow a more fine tuned configuration for comparison.
   */
  public class ObjectSizes
  {
      private static final MemoryMeter meter = MemoryMeter.builder().withGuessing(Guess.INSTRUMENTATION_AND_SPECIFICATION,
                                                                                  Guess.UNSAFE)
                                                                    .build();
  
      private static final long HEAP_BUFFER_SHALLOW_SIZE = measure(ByteBufferUtil.EMPTY_BYTE_BUFFER);
      private static final long DIRECT_BUFFER_SHALLOW_SIZE = measure(ByteBuffer.allocateDirect(0));
      private static final long DIRECT_BUFFER_DEEP_SIZE = measureDeep(ByteBuffer.allocateDirect(0));
  
      public static final long IPV6_SOCKET_ADDRESS_SIZE = ObjectSizes.measureDeep(new InetSocketAddress(getIpvAddress(16), 42));
  
      /**
       * Memory a byte array consumes
       *
       * @param bytes byte array to get memory size
       * @return heap-size of the array
       */
      public static long sizeOfArray(byte[] bytes)
      {
          return meter.measureArray(bytes);
      }
  
      /**
       * Memory a long array consumes
       *
       * @param longs byte array to get memory size
       * @return heap-size of the array
       */
      public static long sizeOfArray(long[] longs)
      {
          return meter.measureArray(longs);
      }
  
      /**
       * Memory an int array consumes
       *
       * @param ints byte array to get memory size
       * @return heap-size of the array
       */
      public static long sizeOfArray(int[] ints)
      {
          return meter.measureArray(ints);
      }
  
      /**
       * Memory a reference array consumes
       *
       * @param length the length of the reference array
       * @return heap-size of the array
       */
      public static long sizeOfReferenceArray(int length)
      {
          return sizeOfArray(length, MEMORY_LAYOUT.getReferenceSize());
      }
  
      /**
       * Memory a reference array consumes itself only
       *
       * @param objects the array to size
       * @return heap-size of the array (excluding memory retained by referenced objects)
       */
      public static long sizeOfArray(Object[] objects)
      {
          return meter.measureArray(objects);
      }
  
      private static long sizeOfArray(int length, int elementSize)
      {
          return computeArraySize(MEMORY_LAYOUT.getArrayHeaderSize(), length, elementSize, MEMORY_LAYOUT.getObjectAlignment());
      }
  
      /**
       * Amount of heap memory consumed by the array of byte buffers. It sums memory consumed by the array itself
       * and for each included byte buffer using {@link #sizeOnHeapOf(ByteBuffer)}.
       */
      public static long sizeOnHeapOf(ByteBuffer[] array)
      {
          if (array == null)
              return 0;
  
          long sum = sizeOfArray(array);
          for (ByteBuffer buffer : array)
              sum += sizeOnHeapOf(buffer);
  
          return sum;
      }
  
      /**
       * Amount of non-data heap memory consumed by the array of byte buffers. It sums memory consumed
       * by the array itself and for each included byte buffer using {@link #sizeOnHeapExcludingDataOf(ByteBuffer)}.
       */
      public static long sizeOnHeapExcludingDataOf(ByteBuffer[] array)
      {
          if (array == null)
              return 0;
  
          long sum = sizeOfArray(array);
          for (ByteBuffer b : array)
              sum += sizeOnHeapExcludingDataOf(b);
  
          return sum;
      }
  
      /**
       * Measures the heap memory used by the specified byte buffer. If the buffer is a slab only the data size will be
       * counted but not the internal overhead. A SLAB is assumed to be created by: {@code buffer.duplicate().position(start).limit(end)} without the use of {@code slice()}.
       * <p>This method makes a certain amount of assumptions:
       *   <ul>
       *       <li>That slabs are always created using: {@code buffer.duplicate().position(start).limit(end)} and not through slice</li>
       *       <li>That the input buffers are not read-only buffers</li>
       *       <li>That the direct buffers that are not slab are not duplicates</li>  
       *   </ul>
       *  Non-respect of those assumptions can lead to an invalid value being returned.
       * @param buffer the buffer to measure
       * @return the heap memory used by the specified byte buffer.
       */
      public static long sizeOnHeapOf(ByteBuffer buffer)
      {
          if (buffer == null)
              return 0;
  
          assert !buffer.isReadOnly();
  
          // We assume here that slabs are always created using: buffer.duplicate().position(start).limit(end) and not through slice
          if (ByteBufferMode.SLAB_ALLOCATION_NO_SLICE.isSlab(buffer))
          {
              if (buffer.isDirect())
                  return DIRECT_BUFFER_SHALLOW_SIZE; // We ignore the underlying buffer
  
              return HEAP_BUFFER_SHALLOW_SIZE + buffer.remaining(); // We ignore the array overhead
          }
  
          if (buffer.isDirect())
              return DIRECT_BUFFER_DEEP_SIZE; // That might not be true if the buffer is a view of another buffer so we could undercount
  
          return HEAP_BUFFER_SHALLOW_SIZE + meter.measureArray(buffer.array());
      }
  
      /**
       * Measures the heap memory used by the specified byte buffer excluding the data. If the buffer shallow size will be counted.
       * A SLAB is assumed to be created by: {@code buffer.duplicate().position(start).limit(end)} without the use of {@code slice()}.
       * <p>This method makes a certain amount of assumptions:
       *   <ul>
       *       <li>That slabs are always created using: {@code buffer.duplicate().position(start).limit(end)} and not through slice</li>
       *       <li>That the input buffers are not read-only buffers</li>
       *       <li>That the direct buffers that are not slab are not duplicates</li>  
       *   </ul>
       *  Non-respect of those assumptions can lead to an invalid value being returned. T 
       * @param buffer the buffer to measure
       * @return the heap memory used by the specified byte buffer excluding the data..
       */
      public static long sizeOnHeapExcludingDataOf(ByteBuffer buffer)
      {
          if (buffer == null)
              return 0;
  
          assert !buffer.isReadOnly();
  
          // We assume here that slabs are always created using: buffer.duplicate().position(start).limit(end) and not through slice
          if (ByteBufferMode.SLAB_ALLOCATION_NO_SLICE.isSlab(buffer))
          {
              if (buffer.isDirect())
                  return DIRECT_BUFFER_SHALLOW_SIZE; // We ignore the underlying buffer
  
              return HEAP_BUFFER_SHALLOW_SIZE; // We ignore the array overhead
          }
  
          if (buffer.isDirect())
              return DIRECT_BUFFER_DEEP_SIZE; // That might not be true if the buffer is a view of another buffer so we could undercount
  
          byte[] bytes = buffer.array();
          return HEAP_BUFFER_SHALLOW_SIZE + meter.measureArray(bytes) - bytes.length;
      }
  
      /**
       * Memory a String consumes
       *
       * @param str String to calculate memory size of
       * @return Total in-memory size of the String
       */
      public static long sizeOf(String str)
      {
          return meter.measureStringDeep(str);
      }
  
      /**
       * @param pojo the object to measure
       * @return the size on the heap of the instance and all retained heap referenced by it, excluding portions of
       * ByteBuffer that are not directly referenced by it but including any other referenced that may also be retained
       * by other objects.
       */
      public static long measureDeep(Object pojo)
      {
          return meter.measureDeep(pojo);
      }
  
      /**
       * @param pojo the object to measure
       * @return The size on the heap of the instance and all retained heap referenced by it, excluding portions of
       * ByteBuffer that are not directly referenced by it but including any other referenced that may also be retained
       * by other objects. This also includes bytes referenced in direct byte buffers, and may double-count memory if
       * it is referenced by multiple ByteBuffer copies.
       */
      public static long measureDeepOmitShared(Object pojo)
      {
          return meter.measureDeep(pojo, ByteBufferMode.SLAB_ALLOCATION_NO_SLICE);
      }
  
      /**
       * @param pojo the object to measure
       * @return the size on the heap of the instance only, excluding any referenced objects
       */
      public static long measure(Object pojo)
      {
          return meter.measure(pojo);
      }
  
      private static InetAddress getIpvAddress(int size)
      {
          if (size == 16 || size ==4)
          {
              try
              {
                  return InetAddress.getByAddress(new byte[size]);
              }
              catch (UnknownHostException e)
              {
                  throw new IllegalArgumentException("Invalid size of a byte array when getting and ipv address: " + size);
              }
          }
          else throw new IllegalArgumentException("Excpected a byte array size of 4 or 16 for an ipv address but got: " + size);
      }
  }
  