alluxio.worker.block.evictor

Class AbstractEvictor

java.lang.Object

alluxio.worker.block.AbstractBlockStoreEventListener

alluxio.worker.block.evictor.AbstractEvictor

All Implemented Interfaces:

BlockStoreEventListener, Evictor

Direct Known Subclasses:

LRFUEvictor, LRUEvictor

@NotThreadSafe
public abstract class AbstractEvictor
extends AbstractBlockStoreEventListener
implements Evictor

Provides the basic implementation for every evictor.

Nested Class Summary

Nested classes/interfaces inherited from interface alluxio.worker.block.evictor.Evictor

Evictor.Factory, Evictor.Mode

Field Summary

Fields

Modifier and Type	Field and Description
protected Allocator	mAllocator
protected BlockMetadataEvictorView	mMetadataView

Constructor Summary

Constructors

Constructor and Description
AbstractEvictor(BlockMetadataEvictorView view, Allocator allocator) Creates a new instance of AbstractEvictor.

Method Summary

Modifier and Type	Method and Description
protected StorageDirEvictorView	cascadingEvict(long bytesToBeAvailable, BlockStoreLocation location, EvictionPlan plan, Evictor.Mode mode) A recursive implementation of cascading eviction.
EvictionPlan	freeSpaceWithView(long bytesToBeAvailable, BlockStoreLocation location, BlockMetadataEvictorView view) Frees space with the guaranteed mode.
EvictionPlan	freeSpaceWithView(long bytesToBeAvailable, BlockStoreLocation location, BlockMetadataEvictorView view, Evictor.Mode mode) Frees space in the given block store location and with the given view.
protected abstract Iterator<Long>	getBlockIterator() Returns an iterator for evictor cache blocks.
protected void	onRemoveBlockFromIterator(long blockId) Performs additional cleanup when a block is removed from the iterator returned by getBlockIterator().
protected BlockStoreLocation	updateBlockStoreLocation(long bytesToBeAvailable, BlockStoreLocation location) Updates the block store location if the evictor wants to free space in a specific location.

Methods inherited from class alluxio.worker.block.AbstractBlockStoreEventListener

onAbortBlock, onAccessBlock, onBlockLost, onCommitBlock, onMoveBlockByClient, onMoveBlockByWorker, onRemoveBlockByClient, onRemoveBlockByWorker, onStorageLost

Methods inherited from class java.lang.Object

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

Field Detail

mAllocator

protected final Allocator mAllocator

mMetadataView

protected BlockMetadataEvictorView mMetadataView

Constructor Detail

AbstractEvictor

public AbstractEvictor(BlockMetadataEvictorView view,
                       Allocator allocator)

Creates a new instance of AbstractEvictor.

Parameters:

view - a view of block metadata information

allocator - an allocation policy

Method Detail

cascadingEvict

protected StorageDirEvictorView cascadingEvict(long bytesToBeAvailable,
                                               BlockStoreLocation location,
                                               EvictionPlan plan,
                                               Evictor.Mode mode)

A recursive implementation of cascading eviction. This method uses a specific eviction strategy to find blocks to evict in the requested location. After eviction, one StorageDir in the location has the specific amount of free space. It then uses an allocation strategy to allocate space in the next tier to move each evicted blocks. If the next tier fails to allocate space for the evicted blocks, the next tier will continue to evict its blocks to free space. This method is only used in freeSpaceWithView(long, BlockStoreLocation, BlockMetadataEvictorView).

Parameters:

bytesToBeAvailable - bytes to be available after eviction

location - target location to evict blocks from

plan - the plan to be recursively updated, is empty when first called in freeSpaceWithView(long, BlockStoreLocation, BlockMetadataEvictorView)

mode - the eviction mode

Returns:

the first StorageDirEvictorView in the range of location to evict/move bytes from, or null if there is no plan

freeSpaceWithView

public EvictionPlan freeSpaceWithView(long bytesToBeAvailable,
                                      BlockStoreLocation location,
                                      BlockMetadataEvictorView view)

Description copied from interface: Evictor

Frees space with the guaranteed mode.

Specified by:

freeSpaceWithView in interface Evictor

Parameters:

bytesToBeAvailable - the amount of free space in bytes to be ensured after eviction

location - the location in block store

view - generated and passed by block store

Returns:

an EvictionPlan (possibly with empty fields) to get the free space, or null if no plan is feasible

freeSpaceWithView

public EvictionPlan freeSpaceWithView(long bytesToBeAvailable,
                                      BlockStoreLocation location,
                                      BlockMetadataEvictorView view,
                                      Evictor.Mode mode)

Description copied from interface: Evictor

Frees space in the given block store location and with the given view. With the GUARANTEED mode, after eviction at least one StorageDir in the location has the specific amount of free space after eviction. The location can be a specific StorageDir, or BlockStoreLocation.anyTier() or BlockStoreLocation.anyDirInTier(String). The view is generated and passed by the calling BlockStore. This method returns null if Evictor fails to propose a feasible plan to meet the requirement.

With the BEST_EFFORT mode, the evictor always returns an eviction plan with toMove and toEvict fields to indicate how to free space. Even if the tier does not have the amount of free space, the evictor returns the plan to free the max space.

If both toMove and toEvict of the plan are empty, it indicates that Evictor has no actions to take and the requirement is already met.

Throws an IllegalArgumentException if the given block location is invalid.

Specified by:

freeSpaceWithView in interface Evictor

Parameters:

bytesToBeAvailable - the amount of free space in bytes to be ensured after eviction

location - the location in block store

view - generated and passed by block store

mode - the eviction mode

Returns:

an EvictionPlan (possibly with empty fields) to get the free space, or null if no plan is feasible

getBlockIterator

protected abstract Iterator<Long> getBlockIterator()

Returns an iterator for evictor cache blocks. The evictor is responsible for specifying the iteration order using its own strategy. For example, LRUEvictor returns an iterator that iterates through the block ids in LRU order.

Returns:

an iterator over the ids of the blocks in the evictor cache

onRemoveBlockFromIterator

protected void onRemoveBlockFromIterator(long blockId)

Performs additional cleanup when a block is removed from the iterator returned by getBlockIterator().

updateBlockStoreLocation

protected BlockStoreLocation updateBlockStoreLocation(long bytesToBeAvailable,
                                                      BlockStoreLocation location)

Updates the block store location if the evictor wants to free space in a specific location. For example, PartialLRUEvictor always evicts blocks from a dir with max free space.

Parameters:

bytesToBeAvailable - bytes to be available after eviction

location - the original block store location

Returns:

the updated block store location