spark core 2.0 MemoryBlock Soruce Code Analysis

最新推荐文章于 2023-03-02 21:01:46 发布

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本文介绍了一个名为MemoryBlock的Java类，该类继承自MemoryLocation，用于表示固定大小的连续内存块。MemoryBlock类包含了一个固定的长度属性，并提供了一个用于获取内存块大小的方法。此外，还提供了一个静态方法用于从长整型数组创建MemoryBlock实例。

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MemoryBlock contains a consecutive block of memory, starting at a MemoryLocation with a fixed size.

public class MemoryBlock extends MemoryLocation {

  private final long length;

  /**
   * Optional page number; used when this MemoryBlock represents a page allocated by a
   * TaskMemoryManager. This field is public so that it can be modified by the TaskMemoryManager,
   * which lives in a different package.
   */
  public int pageNumber = -1;

  public MemoryBlock(@Nullable Object obj, long offset, long length) {
    super(obj, offset);
    this.length = length;
  }

  /**
   * Returns the size in bytes of the memory block.
   */
  public long size() {
    return length;
  }

  /**
   * Creates a memory block pointing to the memory used by the long array.
   */
  public static MemoryBlock fromLongArray(final long[] array) {
    return new MemoryBlock(array, Platform.LONG_ARRAY_OFFSET, array.length * 8L);
  }
}