Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/19222#discussion_r147566203 --- Diff: common/unsafe/src/main/java/org/apache/spark/unsafe/memory/MemoryBlock.java --- @@ -17,47 +17,168 @@ package org.apache.spark.unsafe.memory; -import javax.annotation.Nullable; - import org.apache.spark.unsafe.Platform; +import javax.annotation.Nullable; + /** - * A consecutive block of memory, starting at a {@link MemoryLocation} with a fixed size. + * A declaration of interfaces of MemoryBlock classes . */ -public class MemoryBlock extends MemoryLocation { +public abstract class MemoryBlock { + @Nullable + protected final Object obj; - private final long length; + protected final long offset; + + protected 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. + * TaskMemoryManager. This field can be updated using setPageNumber method so that + * this can be modified by the TaskMemoryManager, which lives in a different package. */ - public int pageNumber = -1; + private int pageNumber = -1; public MemoryBlock(@Nullable Object obj, long offset, long length) { - super(obj, offset); + this.obj = obj; + this.offset = offset; this.length = length; } + public MemoryBlock() { + this(null, 0, 0); + } + + public final Object getBaseObject() { + return obj; + } + + public final long getBaseOffset() { + return offset; + } + /** * Returns the size of the memory block. */ - public long size() { + public final 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); + public final void setPageNumber(int pageNum) { + pageNumber = pageNum; + } + + public final int getPageNumber() { + return pageNumber; } /** * Fills the memory block with the specified byte value. */ - public void fill(byte value) { + public final void fill(byte value) { Platform.setMemory(obj, offset, length, value); } + + /** + * Instantiate the same type of MemoryBlock with new offset and size + */ + public abstract MemoryBlock allocate(long offset, long size); --- End diff -- It's weird to have this interface. I think `MemoryAllocator` is the right place to do it.
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