Memory Management

import org.apache.spark.unsafe.memory.MemoryAllocator;
import org.apache.spark.unsafe.memory.MemoryBlock;
import org.apache.spark.unsafe.memory.MemoryLocation;
import org.apache.spark.unsafe.memory.HeapMemoryAllocator;
import org.apache.spark.unsafe.memory.UnsafeMemoryAllocator;

// Use heap memory allocator
MemoryAllocator heapAllocator = new HeapMemoryAllocator();
MemoryBlock block = heapAllocator.allocate(1024);

// Fill the block with data
block.fill((byte) 0xFF);

// Clean up
heapAllocator.free(block);

// Use unsafe (off-heap) memory allocator
MemoryAllocator unsafeAllocator = new UnsafeMemoryAllocator();
MemoryBlock offHeapBlock = unsafeAllocator.allocate(2048);

// Use the memory block
System.out.println("Block size: " + offHeapBlock.size());

// Clean up
unsafeAllocator.free(offHeapBlock);

// Use global allocator instances
MemoryBlock heapBlock = MemoryAllocator.HEAP.allocate(512);
MemoryBlock unsafeBlock = MemoryAllocator.UNSAFE.allocate(512);

// Clean up
MemoryAllocator.HEAP.free(heapBlock);
MemoryAllocator.UNSAFE.free(unsafeBlock);

// Create memory location
MemoryLocation location = new MemoryLocation(null, 0);

// Update location
byte[] data = new byte[100];
location.setObjAndOffset(data, Platform.BYTE_ARRAY_OFFSET);

// Access location properties
Object baseObject = location.getBaseObject();
long baseOffset = location.getBaseOffset();

long[] array = {1L, 2L, 3L, 4L, 5L};
MemoryBlock arrayBlock = MemoryBlock.fromLongArray(array);

System.out.println("Array block size: " + arrayBlock.size());

public interface MemoryAllocator {
  // Debug configuration constants
  public static final boolean MEMORY_DEBUG_FILL_ENABLED;
  public static final byte MEMORY_DEBUG_FILL_CLEAN_VALUE;
  public static final byte MEMORY_DEBUG_FILL_FREED_VALUE;
  
  // Global allocator instances
  public static final MemoryAllocator UNSAFE;
  public static final MemoryAllocator HEAP;
  
  /**
   * Allocates a contiguous memory block of the specified size.
   */
  MemoryBlock allocate(long size);
  
  /**
   * Frees a previously allocated memory block.
   */
  void free(MemoryBlock memory);
}

public class MemoryBlock {
  // Page number constants for TaskMemoryManager integration
  public static final int NO_PAGE_NUMBER;
  public static final int FREED_IN_TMM_PAGE_NUMBER;
  public static final int FREED_IN_ALLOCATOR_PAGE_NUMBER;
  
  // Optional page number for TaskMemoryManager allocated pages
  public int pageNumber;
  
  /**
   * Creates memory block with specified base object, offset, and length.
   */
  public MemoryBlock(Object obj, long offset, long length);
  
  /**
   * Returns the size of this memory block in bytes.
   */
  public long size();
  
  /**
   * Fills the entire memory block with the specified byte value.
   */
  public void fill(byte value);
  
  /**
   * Creates a memory block wrapping a long array.
   */
  public static MemoryBlock fromLongArray(long[] array);
}

public class MemoryLocation {
  /**
   * Creates memory location with specified base object and offset.
   */
  public MemoryLocation(Object obj, long offset);
  
  /**
   * Creates memory location with null base and zero offset.
   */
  public MemoryLocation();
  
  /**
   * Updates the base object and offset of this memory location.
   */
  public void setObjAndOffset(Object newObj, long newOffset);
  
  /**
   * Returns the base object for memory access.
   */
  public Object getBaseObject();
  
  /**
   * Returns the base offset for memory access.
   */
  public long getBaseOffset();
}

public class HeapMemoryAllocator implements MemoryAllocator {
  /**
   * Allocates heap memory block of specified size.
   */
  public MemoryBlock allocate(long size);
  
  /**
   * Frees previously allocated heap memory block.
   */
  public void free(MemoryBlock memory);
}

public class UnsafeMemoryAllocator implements MemoryAllocator {
  /**
   * Allocates off-heap memory block using unsafe operations.
   */
  public MemoryBlock allocate(long size);
  
  /**
   * Frees previously allocated off-heap memory block.
   */
  public void free(MemoryBlock memory);
}