org.terracotta.offheapstore.paging

Class UpfrontAllocatingPageSource

java.lang.Object

org.terracotta.offheapstore.paging.UpfrontAllocatingPageSource

All Implemented Interfaces:

PageSource

public class UpfrontAllocatingPageSource
extends Object
implements PageSource

An upfront allocating direct byte buffer source.

This buffer source implementation allocates all of its required storage up-front in fixed size chunks. Runtime allocations are then satisfied using slices from these initial chunks.

Author:

Chris Dennis

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	UpfrontAllocatingPageSource.ThresholdDirection

Field Summary

Fields

Modifier and Type	Field and Description
static String	ALLOCATION_LOG_LOCATION

Constructor Summary

Constructors

Constructor and Description
UpfrontAllocatingPageSource(BufferSource source, long toAllocate, int chunkSize) Create an up-front allocating buffer source of toAllocate total bytes, in chunkSize byte chunks.
UpfrontAllocatingPageSource(BufferSource source, long toAllocate, int maxChunk, int minChunk) Create an up-front allocating buffer source of toAllocate total bytes, in maximally sized chunks, within the given bounds.

Method Summary

Modifier and Type	Method and Description
Runnable	addAllocationThreshold(UpfrontAllocatingPageSource.ThresholdDirection direction, long threshold, Runnable action) Adds an allocation threshold action.
Page	allocate(int size, boolean thief, boolean victim, OffHeapStorageArea owner) Allocates a byte buffer of at least the given size.
void	free(Page page) Frees the supplied buffer.
long	getAllocatedSize()
long	getAllocatedSizeUnSync()
long	getCapacity() Return the total allocated capacity, used or not
Runnable	removeAllocationThreshold(UpfrontAllocatingPageSource.ThresholdDirection direction, long threshold) Removes an allocation threshold action.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

ALLOCATION_LOG_LOCATION

public static final String ALLOCATION_LOG_LOCATION

Constructor Detail

UpfrontAllocatingPageSource

public UpfrontAllocatingPageSource(BufferSource source,
                                   long toAllocate,
                                   int chunkSize)

Create an up-front allocating buffer source of toAllocate total bytes, in chunkSize byte chunks.

Parameters:

source - source from which initial buffers will be allocated

toAllocate - total space to allocate in bytes

chunkSize - chunkSize size to allocate in bytes

UpfrontAllocatingPageSource

public UpfrontAllocatingPageSource(BufferSource source,
                                   long toAllocate,
                                   int maxChunk,
                                   int minChunk)

Create an up-front allocating buffer source of toAllocate total bytes, in maximally sized chunks, within the given bounds.

Parameters:

source - source from which initial buffers will be allocated

toAllocate - total space to allocate in bytes

maxChunk - the largest chunk size in bytes

minChunk - the smallest chunk size in bytes

Method Detail

getCapacity

public long getCapacity()

Return the total allocated capacity, used or not

Returns:

the total capacity

allocate

public Page allocate(int size,
                     boolean thief,
                     boolean victim,
                     OffHeapStorageArea owner)

Allocates a byte buffer of at least the given size.

This BufferSource is limited to allocating regions that are a power of two in size. Supplied sizes are therefore rounded up to the next largest power of two.

Specified by:

allocate in interface PageSource

Parameters:

size - size of page to allocate

thief - true if the allocation can steal space from victims

victim - true if the allocated page should be eligible for stealing

owner - owner from which subsequent steal should occur

Returns:

a buffer of at least the given size

free

public void free(Page page)

Frees the supplied buffer.

If the given buffer was not allocated by this source or has already been freed then an AssertionError is thrown.

Specified by:

free in interface PageSource

getAllocatedSize

public long getAllocatedSize()

getAllocatedSizeUnSync

public long getAllocatedSizeUnSync()

toString

public String toString()

Overrides:

toString in class Object

addAllocationThreshold

public Runnable addAllocationThreshold(UpfrontAllocatingPageSource.ThresholdDirection direction,
                                       long threshold,
                                       Runnable action)

Adds an allocation threshold action.

There can be only a single action associated with each unique direction and threshold combination. If an action is already associated with the supplied combination then the action is replaced by the new action and the old action is returned.

Actions are fired on passing through the supplied threshold and are called synchronously with the triggering allocation. This means care must be taken to avoid mutating any map that uses this page source from within the action otherwise deadlocks may result. Exceptions thrown by the action will be caught and logged by the page source and will not be propagated on the allocating thread.

Parameters:

direction - new actions direction

threshold - new actions threshold level

action - fired on breaching the threshold

Returns:

the replaced action or null if no action was present.

removeAllocationThreshold

public Runnable removeAllocationThreshold(UpfrontAllocatingPageSource.ThresholdDirection direction,
                                          long threshold)

Removes an allocation threshold action.

Removes the allocation threshold action for the given level and direction.

Parameters:

direction - registered actions direction

threshold - registered actions threshold level

Returns:

the removed condition or null if no action was present.