DefaultCacheManager.java
/*
* *********************************************************************************************************************
*
* blueMarine II: Semantic Media Centre
* http://tidalwave.it/projects/bluemarine2
*
* Copyright (C) 2015 - 2021 by Tidalwave s.a.s. (http://tidalwave.it)
*
* *********************************************************************************************************************
*
* 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.
*
* *********************************************************************************************************************
*
* git clone https://bitbucket.org/tidalwave/bluemarine2-src
* git clone https://github.com/tidalwave-it/bluemarine2-src
*
* *********************************************************************************************************************
*/
package it.tidalwave.bluemarine2.model.impl;
import javax.annotation.Nonnull;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;
import java.lang.ref.SoftReference;
import it.tidalwave.messagebus.annotation.ListensTo;
import it.tidalwave.messagebus.annotation.SimpleMessageSubscriber;
import it.tidalwave.bluemarine2.message.PersistenceInitializedNotification;
import it.tidalwave.bluemarine2.model.spi.CacheManager;
import lombok.extern.slf4j.Slf4j;
import lombok.RequiredArgsConstructor;
import static java.util.Objects.*;
/***********************************************************************************************************************
*
* @author Fabrizio Giudici
*
**********************************************************************************************************************/
@Slf4j @SimpleMessageSubscriber
public class DefaultCacheManager implements CacheManager
{
private final Map<Object, Cache> cacheMap = new ConcurrentHashMap<>();
@RequiredArgsConstructor
static class DefaultCache implements Cache
{
@Nonnull
private final String name;
// TODO: use Spring ConcurrentReferenceHashMap?
private final Map<Object, SoftReference<?>> objectMap = new ConcurrentHashMap<>();
@Override @Nonnull
public <T> T getCachedObject (@Nonnull final Object key, @Nonnull final Supplier<T> supplier)
{
SoftReference<T> ref = (SoftReference<T>)(objectMap.computeIfAbsent(key, k -> computeObject(k, supplier)));
T object = ref.get();
if (object == null)
{
objectMap.put(key, ref = computeObject(key, supplier));
object = requireNonNull(ref.get(), "Cache returned null");
}
return object;
}
@Nonnull
private <T> SoftReference<T> computeObject (@Nonnull final Object key, @Nonnull final Supplier<T> supplier)
{
log.info(">>>> cache {} miss for {}", name, key);
return new SoftReference<>(requireNonNull(supplier.get(), "Supplier returned null"));
}
}
@Override @Nonnull
public Cache getCache (@Nonnull final Object cacheKey)
{
return cacheMap.computeIfAbsent(cacheKey, key -> new DefaultCache(cacheKey.toString()));
}
/* visible for testing FIXME */ public void onPersistenceUpdated (@ListensTo final PersistenceInitializedNotification notification)
{
log.debug("onPersistenceUpdated({})", notification);
cacheMap.clear();
}
}