alluxio.worker.block.evictor

Class GreedyEvictor

java.lang.Object

alluxio.worker.block.evictor.GreedyEvictor

All Implemented Interfaces:

Evictor

@ThreadSafe
public final class GreedyEvictor
extends Object
implements Evictor

A simple evictor that evicts arbitrary blocks until the required size is met. This class serves as an example to implement an Evictor. It does not use the block metadata information or the allocation policy to determine which blocks should be evicted.

Nested Class Summary

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

Evictor.Factory, Evictor.Mode

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
EvictionPlan	freeSpaceWithView(long availableBytes, BlockStoreLocation location, BlockMetadataEvictorView view) Frees space with the guaranteed mode.
EvictionPlan	freeSpaceWithView(long availableBytes, BlockStoreLocation location, BlockMetadataEvictorView view, Evictor.Mode mode) Frees space in the given block store location and with the given view.

Methods inherited from class java.lang.Object

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

Constructor Detail

GreedyEvictor

public GreedyEvictor(BlockMetadataEvictorView view,
                     Allocator allocator)

Creates a new instance of GreedyEvictor.

Parameters:

view - a view of block metadata information

allocator - an allocation policy

Method Detail

freeSpaceWithView

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

Description copied from interface: Evictor

Frees space with the guaranteed mode.

Specified by:

freeSpaceWithView in interface Evictor

Parameters:

availableBytes - 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 availableBytes,
                                      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:

availableBytes - 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