net.sf.ehcache.pool.impl.AbstractFromLargestCachePoolEvictor Maven / Gradle / Ivy
/**
* Copyright 2003-2010 Terracotta, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.sf.ehcache.pool.impl;
import net.sf.ehcache.pool.PoolEvictor;
import net.sf.ehcache.pool.PoolableStore;
import java.util.ArrayList;
import java.util.Collection;
/**
* Abstract pool evictor which always evicts from the store consuming the most resources.
*
* @author Ludovic Orban
*/
public abstract class AbstractFromLargestCachePoolEvictor implements PoolEvictor {
/**
* {@inheritDoc}
*/
public boolean freeSpace(Collection from, long bytes) {
if (from == null || from.isEmpty()) {
return false;
}
long remainingSizeInBytes = bytes;
Collection tried = new ArrayList();
while (tried.size() != from.size()) {
PoolableStore largestPoolableStore = findUntriedLargestPoolableStore(from, tried);
long beforeEvictionSize = getSizeInBytes(largestPoolableStore);
if (!evict(1, bytes, largestPoolableStore)) {
tried.add(largestPoolableStore);
continue;
}
long afterEvictionSize = getSizeInBytes(largestPoolableStore);
remainingSizeInBytes -= (beforeEvictionSize - afterEvictionSize);
if (remainingSizeInBytes <= 0L) {
return true;
}
}
return false;
}
/**
* Evict from a store for a chosen resource
*
* @param count the element count
* @param bytes the bytes count
* @param poolableStore the store
* @return true if eviction succeeded, ie: if there was enough evictable resource held by the store
*/
protected abstract boolean evict(int count, long bytes, PoolableStore poolableStore);
/**
* Get a store size in bytes for a chosen resource
*
* @param poolableStore the store
* @return the size in bytes
*/
protected abstract long getSizeInBytes(PoolableStore poolableStore);
private PoolableStore findUntriedLargestPoolableStore(Collection from, Collection tried) {
PoolableStore largestPoolableStore = null;
for (PoolableStore poolableStore : from) {
if (alreadyTried(tried, poolableStore)) {
continue;
}
if (largestPoolableStore == null || getSizeInBytes(poolableStore) > getSizeInBytes(largestPoolableStore)) {
largestPoolableStore = poolableStore;
}
}
return largestPoolableStore;
}
private boolean alreadyTried(Collection tried, PoolableStore from) {
for (PoolableStore poolableStore : tried) {
if (poolableStore == from) {
return true;
}
}
return false;
}
}