Package org.apache.arrow.memory

Class AllocationManager

java.lang.Object

org.apache.arrow.memory.AllocationManager

Direct Known Subclasses:

NettyAllocationManager, UnsafeAllocationManager

public abstract class AllocationManager
extends Object

An AllocationManager is the implementation of a physical memory allocation.

Manages the relationship between the allocators and a particular memory allocation. Ensures that one allocator owns the memory that multiple allocators may be referencing. Manages a BufferLedger between each of its associated allocators. It does not track the reference count; that is the role of BufferLedger (aka ReferenceManager).

This is a public interface implemented by concrete allocator implementations (e.g. Netty or Unsafe).

Threading: AllocationManager manages thread-safety internally. Operations within the context of a single BufferLedger are lockless in nature and can be leveraged by multiple threads. Operations that cross the context of two ledgers will acquire a lock on the AllocationManager instance. Important note, there is one AllocationManager per physical buffer allocation. As such, there will be thousands of these in a typical query. The contention of acquiring a lock on AllocationManager should be very low.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	AllocationManager.Factory	A factory interface for creating AllocationManager.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AllocationManager(BufferAllocator accountingAllocator)

Method Summary

Modifier and Type	Method	Description
abstract long	getSize()	Return the size of underlying chunk of memory managed by this Allocation Manager.
protected abstract long	memoryAddress()	Return the absolute memory address pointing to the fist byte of underlying memory chunk.
protected abstract void	release0()	Release the underlying memory chunk.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AllocationManager

protected AllocationManager(BufferAllocator accountingAllocator)

Method Details

getSize

public abstract long getSize()

Return the size of underlying chunk of memory managed by this Allocation Manager.

The underlying memory chunk managed can be different from the original requested size.

Returns:

size of underlying memory chunk

memoryAddress

protected abstract long memoryAddress()

Return the absolute memory address pointing to the fist byte of underlying memory chunk.

release0

protected abstract void release0()

Release the underlying memory chunk.