org.apache.arrow.memory

Class AllocationManager.BufferLedger

java.lang.Object

org.apache.arrow.memory.AllocationManager.BufferLedger

All Implemented Interfaces:

ValueWithKeyIncluded<BaseAllocator>

Enclosing class:

AllocationManager

public class AllocationManager.BufferLedger
extends Object
implements ValueWithKeyIncluded<BaseAllocator>

The reference manager that binds an allocator manager to a particular BaseAllocator. Also responsible for creating a set of ArrowBufs that share a common fate and set of reference counts. As with AllocationManager, the only reason this is public is due to ArrowBuf being in io .netty.buffer package.

Method Summary

Methods

Modifier and Type	Method and Description
int	decrement(int decrement) Decrement the ledger's reference count.
int	getAccountedSize() How much memory is accounted for by this ledger.
BaseAllocator	getKey()
AllocationManager.BufferLedger	getLedgerForAllocator(BufferAllocator allocator) Returns the ledger associated with a particular BufferAllocator.
int	getSize() What is the total size (in bytes) of memory underlying this ledger.
ArrowBuf	newArrowBuf(int offset, int length) Create a new ArrowBuf associated with this AllocationManager and memory.
ArrowBuf	newArrowBuf(int offset, int length, BufferManager manager) Create a new ArrowBuf associated with this AllocationManager and memory.
void	print(StringBuilder sb, int indent, BaseAllocator.Verbosity verbosity) Print the current ledger state to a the provided StringBuilder.
boolean	transferBalance(AllocationManager.BufferLedger target) Transfer any balance the current ledger has to the target ledger.

Methods inherited from class java.lang.Object

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

Method Detail

getKey

public BaseAllocator getKey()

Specified by:

getKey in interface ValueWithKeyIncluded<BaseAllocator>

transferBalance

public boolean transferBalance(AllocationManager.BufferLedger target)

Transfer any balance the current ledger has to the target ledger. In the case that the current ledger holds no memory, no transfer is made to the new ledger.

Parameters:

target - The ledger to transfer ownership account to.

Returns:

Whether transfer fit within target ledgers limits.

print

public void print(StringBuilder sb,
         int indent,
         BaseAllocator.Verbosity verbosity)

Print the current ledger state to a the provided StringBuilder.

Parameters:

sb - The StringBuilder to populate.

indent - The level of indentation to position the data.

verbosity - The level of verbosity to print.

decrement

public int decrement(int decrement)

Decrement the ledger's reference count. If the ledger is decremented to zero, this ledger should release its ownership back to the AllocationManager

Parameters:

decrement - amout to decrease the reference count by

Returns:

the new reference count

getLedgerForAllocator

public AllocationManager.BufferLedger getLedgerForAllocator(BufferAllocator allocator)

Returns the ledger associated with a particular BufferAllocator. If the BufferAllocator doesn't currently have a ledger associated with this AllocationManager, a new one is created. This is placed on BufferLedger rather than AllocationManager directly because ArrowBufs don't have access to AllocationManager and they are the ones responsible for exposing the ability to associate multiple allocators with a particular piece of underlying memory. Note that this will increment the reference count of this ledger by one to ensure the ledger isn't destroyed before use.

Parameters:

allocator - A BufferAllocator.

Returns:

The ledger associated with the BufferAllocator.

newArrowBuf

public ArrowBuf newArrowBuf(int offset,
                   int length)

Create a new ArrowBuf associated with this AllocationManager and memory. Does not impact reference count. Typically used for slicing.

Parameters:

offset - The offset in bytes to start this new ArrowBuf.

length - The length in bytes that this ArrowBuf will provide access to.

Returns:

A new ArrowBuf that shares references with all ArrowBufs associated with this BufferLedger

newArrowBuf

public ArrowBuf newArrowBuf(int offset,
                   int length,
                   BufferManager manager)

Create a new ArrowBuf associated with this AllocationManager and memory.

Parameters:

offset - The offset in bytes to start this new ArrowBuf.

length - The length in bytes that this ArrowBuf will provide access to.

manager - An optional BufferManager argument that can be used to manage expansion of this ArrowBuf

Returns:

A new ArrowBuf that shares references with all ArrowBufs associated with this BufferLedger

getSize

public int getSize()

What is the total size (in bytes) of memory underlying this ledger.

Returns:

Size in bytes

getAccountedSize

public int getAccountedSize()

How much memory is accounted for by this ledger. This is either getSize() if this is the owning ledger for the memory or zero in the case that this is not the owning ledger associated with this memory.

Returns:

Amount of accounted(owned) memory associated with this ledger.