/*
* Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.map.impl.eviction;
import com.hazelcast.core.EntryView;
import com.hazelcast.map.eviction.MapEvictionPolicy;
import com.hazelcast.map.impl.record.Record;
import com.hazelcast.map.impl.recordstore.LazyEntryViewFromRecord;
import com.hazelcast.map.impl.recordstore.RecordStore;
import com.hazelcast.map.impl.recordstore.Storage;
import com.hazelcast.nio.serialization.Data;
import com.hazelcast.spi.partition.IPartition;
import com.hazelcast.spi.partition.IPartitionService;
import com.hazelcast.util.Clock;
import static com.hazelcast.util.Preconditions.checkNotNull;
/**
* Evictor helper methods.
*/
public class EvictorImpl implements Evictor {
protected final EvictionChecker evictionChecker;
protected final IPartitionService partitionService;
protected final MapEvictionPolicy mapEvictionPolicy;
public EvictorImpl(MapEvictionPolicy mapEvictionPolicy,
EvictionChecker evictionChecker, IPartitionService partitionService) {
this.evictionChecker = checkNotNull(evictionChecker);
this.partitionService = checkNotNull(partitionService);
this.mapEvictionPolicy = checkNotNull(mapEvictionPolicy);
}
@Override
public void evict(RecordStore recordStore, Data excludedKey) {
EntryView evictableEntry = selectEvictableEntry(recordStore, excludedKey);
if (evictableEntry == null) {
return;
}
evictEntry(recordStore, evictableEntry);
}
private EntryView selectEvictableEntry(RecordStore recordStore, Data excludedKey) {
Iterable<EntryView> samples = getSamples(recordStore);
EntryView excluded = null;
EntryView selected = null;
for (EntryView candidate : samples) {
if (excludedKey != null && excluded == null && getDataKey(candidate).equals(excludedKey)) {
excluded = candidate;
continue;
}
if (selected == null) {
selected = candidate;
} else if (mapEvictionPolicy.compare(candidate, selected) < 0) {
selected = candidate;
}
}
return selected == null ? excluded : selected;
}
private Data getDataKey(EntryView candidate) {
return getRecordFromEntryView(candidate).getKey();
}
private void evictEntry(RecordStore recordStore, EntryView selectedEntry) {
Record record = getRecordFromEntryView(selectedEntry);
Data key = record.getKey();
if (recordStore.isLocked(record.getKey())) {
return;
}
boolean backup = isBackup(recordStore);
recordStore.evict(key, backup);
if (!backup) {
recordStore.doPostEvictionOperations(record, backup);
}
}
@Override
public boolean checkEvictable(RecordStore recordStore) {
return evictionChecker.checkEvictable(recordStore);
}
// this method is overridden in another context.
protected Record getRecordFromEntryView(EntryView selectedEntry) {
return ((LazyEntryViewFromRecord) selectedEntry).getRecord();
}
protected boolean isBackup(RecordStore recordStore) {
int partitionId = recordStore.getPartitionId();
IPartition partition = partitionService.getPartition(partitionId, false);
return !partition.isLocal();
}
protected Iterable<EntryView> getSamples(RecordStore recordStore) {
Storage storage = recordStore.getStorage();
return (Iterable<EntryView>) storage.getRandomSamples(SAMPLE_COUNT);
}
protected static long getNow() {
return Clock.currentTimeMillis();
}
}