
uk.gov.gchq.gaffer.cache.CacheServiceLoader Maven / Gradle / Ivy
/*
* Copyright 2016-2023 Crown Copyright
*
* 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 uk.gov.gchq.gaffer.cache;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import uk.gov.gchq.gaffer.cache.util.CacheProperties;
import java.util.Properties;
/**
* Initialised when the store is initialised. Looks at a system property to determine the cache service to load.
* Then initialises it, after which any component may use {@code CacheServiceLoader.getService()} to get the service
* that can retrieve the appropriate cache.
*/
public final class CacheServiceLoader {
private static final Logger LOGGER = LoggerFactory.getLogger(CacheServiceLoader.class);
private static ICacheService service;
private static boolean shutdownHookAdded = false;
/**
* Looks at a system property and initialises an appropriate cache service. Adds a shutdown hook
* which gracefully closes the cache service if JVM is stopped. This should not be relied upon
* in a servlet context - use the ServletLifecycleListener located in the REST module instead
*
* @param properties the cache service properties
* @throws IllegalArgumentException if an invalid cache class is specified in the system property
*/
public static void initialise(final Properties properties) {
if (null == properties) {
LOGGER.warn("received null properties - exiting initialise method without creating service");
return;
}
final String cacheClass = properties.getProperty(CacheProperties.CACHE_SERVICE_CLASS);
if (null == cacheClass) {
if (null == service) {
LOGGER.debug("No cache service class was specified in properties.");
}
return;
}
if (isEnabled()) {
LOGGER.debug("Will not initialise as Cache service was already enabled.");
return;
}
try {
service = Class.forName(cacheClass).asSubclass(ICacheService.class).newInstance();
} catch (final InstantiationException | IllegalAccessException | ClassNotFoundException e) {
throw new IllegalArgumentException("Failed to instantiate cache using class " + cacheClass, e);
}
service.initialise(properties);
if (!shutdownHookAdded) {
Runtime.getRuntime().addShutdownHook(new Thread(CacheServiceLoader::shutdown));
shutdownHookAdded = true;
}
}
/**
* Get the cache service object.
*
* @return the cache service
*/
@SuppressFBWarnings(value = "MS_EXPOSE_REP", justification = "Intended behaviour")
public static ICacheService getService() {
return service;
}
/**
* @return true if the cache is enabled
*/
public static boolean isEnabled() {
return null != service;
}
/**
* Gracefully shutdown and reset the cache service.
*/
public static void shutdown() {
if (null != service) {
service.shutdown();
}
service = null;
}
private CacheServiceLoader() {
// private constructor to prevent instantiation
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy