/*
* The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
* (the "License"). You may not use this work except in compliance with the License, which is
* available at www.apache.org/licenses/LICENSE-2.0
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied, as more fully set forth in the License.
*
* See the NOTICE file distributed with this work for information regarding copyright ownership.
*/
package alluxio.worker.block.evictor;
import alluxio.Configuration;
import alluxio.PropertyKey;
import alluxio.annotation.PublicApi;
import alluxio.util.CommonUtils;
import alluxio.worker.block.BlockMetadataManagerView;
import alluxio.worker.block.BlockStoreLocation;
import alluxio.worker.block.allocator.Allocator;
import java.lang.RuntimeException;
import javax.annotation.concurrent.ThreadSafe;
/**
* Interface for the eviction policy in Alluxio.
*/
@PublicApi
public interface Evictor {
/**
* Factory for {@link Evictor}.
*/
@ThreadSafe
class Factory {
private Factory() {} // prevent instantiation
/**
* Factory for {@link Evictor}.
*
* @param view {@link BlockMetadataManagerView} to pass to {@link Evictor}
* @param allocator an allocation policy
* @return the generated {@link Evictor}
*/
public static Evictor create(BlockMetadataManagerView view, Allocator allocator) {
try {
return CommonUtils.createNewClassInstance(
Configuration.<Evictor>getClass(PropertyKey.WORKER_EVICTOR_CLASS),
new Class[]{BlockMetadataManagerView.class, Allocator.class},
new Object[]{view, allocator});
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
/**
* Frees space in the given block store location and with the given view. After eviction, at least
* one {@link alluxio.worker.block.meta.StorageDir} in the location has the specific amount of
* free space after eviction. The location can be a specific
* {@link alluxio.worker.block.meta.StorageDir}, or {@link BlockStoreLocation#anyTier()} or
* {@link BlockStoreLocation#anyDirInTier(String)}. The view is generated and passed by the
* calling {@link alluxio.worker.block.BlockStore}.
* <p>
* This method returns null if {@link Evictor} fails to propose a feasible plan to meet the
* requirement, or an eviction plan with toMove and toEvict fields to indicate how to free space.
* If both toMove and toEvict of the plan are empty, it indicates that {@link Evictor} has no
* actions to take and the requirement is already met.
*
* Throws an {@link IllegalArgumentException} if the given block location is invalid.
*
* @param availableBytes the amount of free space in bytes to be ensured after eviction
* @param location the location in block store
* @param view generated and passed by block store
* @return an {@link EvictionPlan} (possibly with empty fields) to get the free space, or null if
* no plan is feasible
*/
EvictionPlan freeSpaceWithView(long availableBytes, BlockStoreLocation location,
BlockMetadataManagerView view);
}