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Contains the entire NEBA core implementation, i.e. the framework that interprets the NEBA API annotations and provides implementations for the service and lifecycle callback interfaces provided in the NEBA API. This package must not export anything as its implementation details are entirely private.

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/*
  Copyright 2013 the original author or authors.
  
  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 io.neba.core.blueprint;

import io.neba.core.mvc.MvcServlet;
import io.neba.core.resourcemodels.registration.ModelRegistrar;
import org.osgi.framework.Bundle;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * Base class for services reacting to context shutdowns.
 * Operations performed by the event handling parties may
 * encounter further locks which may be blocked by threads waiting for the
 * {@link io.neba.core.blueprint.EventhandlingBarrier}, thus resulting in a deadlock. 

 * To prevent this, it is recommended that any event handling is
 * performed {@link org.springframework.scheduling.annotation.Async asynchronously}.
 *
 * @author Olaf Otto
 */
public abstract class ContextShutdownHandler {
    private final Logger logger = LoggerFactory.getLogger(getClass());
    @Autowired
    private ModelRegistrar modelRegistrar;
    @Autowired
    private MvcServlet dispatcherServlet;
    @Autowired
    private EventhandlingBarrier barrier;

    /**
     * We must guarantee the order in which the event is consumed by the
     * collaborators since subsequent operations may depend on the resulting
     * state.
     *
     * @param bundle must not be null.
     */
    public void handleStop(Bundle bundle) {
        if (bundle == null) {
            throw new IllegalArgumentException("Method argument bundle must not be null.");
        }

        this.logger.info("Removing infrastructure for bundle: " + bundle + "...");
        this.barrier.begin();
        try {
            this.modelRegistrar.unregister(bundle);
            this.dispatcherServlet.disableMvc(bundle);
        } finally {
            this.barrier.end();
        }
        this.logger.info("Infrastructure for " + bundle + " removed.");
    }
}