alluxio.worker.block.evictor

Interface Evictor

All Known Implementing Classes:

AbstractEvictor, LRUEvictor

@PublicApi
public interface Evictor

Interface for the eviction policy in Alluxio.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Evictor.Factory Factory for Evictor.
static class	Evictor.Mode The eviction mode.

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.

Method Detail

freeSpaceWithView

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

Frees space with the guaranteed mode.

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

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

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.

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