org.apache.arrow.memory

Interface AllocationListener

public interface AllocationListener

An allocation listener being notified for allocation/deallocation

It might be called from multiple threads if the allocator hierarchy shares a listener, in which case, the provider should take care of making the implementation thread-safe.

Field Summary

Fields

Modifier and Type	Field and Description
static AllocationListener	NOOP

Method Summary

Modifier and Type	Method and Description
default void	onAllocation(long size) Called each time a new buffer has been allocated.
default void	onChildAdded(BufferAllocator parentAllocator, BufferAllocator childAllocator) Called immediately after a child allocator was added to the parent allocator.
default void	onChildRemoved(BufferAllocator parentAllocator, BufferAllocator childAllocator) Called immediately after a child allocator was removed from the parent allocator.
default boolean	onFailedAllocation(long size, AllocationOutcome outcome) Called whenever an allocation failed, giving the caller a chance to create some space in the allocator (either by freeing some resource, or by changing the limit), and, if successful, allowing the allocator to retry the allocation.
default void	onPreAllocation(long size) Called each time a new buffer has been requested.
default void	onRelease(long size) Informed each time a buffer is released from allocation.

Field Detail

NOOP

static final AllocationListener NOOP

Method Detail

onPreAllocation

default void onPreAllocation(long size)

Called each time a new buffer has been requested.

An exception can be safely thrown by this method to terminate the allocation.

Parameters:

size - the buffer size being allocated

onAllocation

default void onAllocation(long size)

Called each time a new buffer has been allocated.

An exception cannot be thrown by this method.

Parameters:

size - the buffer size being allocated

onRelease

default void onRelease(long size)

Informed each time a buffer is released from allocation.

An exception cannot be thrown by this method.

Parameters:

size - The size of the buffer being released.

onFailedAllocation

default boolean onFailedAllocation(long size,
                                   AllocationOutcome outcome)

Called whenever an allocation failed, giving the caller a chance to create some space in the allocator (either by freeing some resource, or by changing the limit), and, if successful, allowing the allocator to retry the allocation.

Parameters:

size - the buffer size that was being allocated

outcome - the outcome of the failed allocation. Carries information of what failed

Returns:

true, if the allocation can be retried; false if the allocation should fail

onChildAdded

default void onChildAdded(BufferAllocator parentAllocator,
                          BufferAllocator childAllocator)

Called immediately after a child allocator was added to the parent allocator.

Parameters:

parentAllocator - The parent allocator to which a child was added

childAllocator - The child allocator that was just added

onChildRemoved

default void onChildRemoved(BufferAllocator parentAllocator,
                            BufferAllocator childAllocator)

Called immediately after a child allocator was removed from the parent allocator.

Parameters:

parentAllocator - The parent allocator from which a child was removed

childAllocator - The child allocator that was just removed