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Ehcache is an open source, standards-based cache used to boost performance,
offload the database and simplify scalability. Ehcache is robust, proven and full-featured and
this has made it the most widely-used Java-based cache.
/*
* All content copyright (c) 2003-2012 Terracotta, Inc., except as may otherwise be noted in a separate copyright
* notice. All rights reserved.
*/
package org.terracotta.management;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
/**
* Implements a dynamic service locator, (see
* http://martinfowler.com/articles/injection.html#UsingAServiceLocator)
*
* The intended use case is the following :
* 1) Initialization
* ServiceLocator locator = new ServiceLocator();
* ConfigServiceImpl configServiceImpl = new ConfigServiceImpl();
* AgentEntity agentEntity = new AgentEntity();
* locator.loadService(ConfigService.class, configServiceImpl).loadService(Serializable.class, agentEntity);
* ServiceLocator.load(locator);
*
* 2) Use of the service locator in the same class loader
* ConfigService value = ServiceLocator.locate(ConfigService.class);
*
* You can not load it more than once (unless you call unload()); you can not start locating before load() was called
*
*
*/
public class ServiceLocator {
private static final AtomicReference, Object>> installedServices = new AtomicReference, Object>>();
private final Map, Object> services = new HashMap, Object>();
public final ServiceLocator loadService(Class clazz, T implementation) {
services.put(clazz, implementation);
return this;
}
public static T locate(Class typeToReturn) {
Map, Object> m = installedServices.get();
if (m == null) {
throw new IllegalStateException("The service locator has not been initialized yet ! (through the load() method)");
}
else {
return (T) m.get(typeToReturn);
}
}
public static void load(ServiceLocator locator) {
// no special need for an immutable map, since installedServices is only accessed for read
Map, Object> services = Collections.unmodifiableMap(new HashMap, Object>(locator.services));
if (!installedServices.compareAndSet(null, services)) {
throw new IllegalStateException("The service locator has already been initialized (through the load() method)");
}
}
public static void unload() {
installedServices.set(null);
}
}