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package org.glassfish.gms.bootstrap;

import com.sun.enterprise.config.serverbeans.Cluster;
import com.sun.enterprise.config.serverbeans.Clusters;
import com.sun.enterprise.config.serverbeans.Config;
import com.sun.enterprise.config.serverbeans.Server;
import com.sun.enterprise.ee.cms.core.GMSConstants;
import com.sun.enterprise.ee.cms.core.GroupManagementService;
import com.sun.enterprise.ee.cms.core.ServiceProviderConfigurationKeys;
import com.sun.enterprise.module.bootstrap.StartupContext;
import com.sun.enterprise.util.i18n.StringManager;
import com.sun.hk2.component.ExistingSingletonInhabitant;
import com.sun.logging.LogDomains;

import java.beans.PropertyChangeEvent;
import java.util.LinkedList;
import java.util.List;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.api.Startup;
import org.glassfish.api.admin.ServerEnvironment;
import org.jvnet.hk2.annotations.Inject;
import org.jvnet.hk2.annotations.Service;
import org.jvnet.hk2.component.Habitat;
import org.jvnet.hk2.component.PostConstruct;
import org.jvnet.hk2.config.*;
import org.jvnet.hk2.config.types.Property;

/**
 * This service is responsible for loading the group management
 * service. In the DAS, GMS will only be enabled if there is at least
 * one cluster present with the gms-enabled attribute set to true.
 * In an instance, GMS will be enabled if the cluster containing this
 * instance has gms-enabled set to true.
 *
 * Components can inject this service in order to obtain a reference
 * to a GMSAdapter object. From this, the appropriate GroupManagementService
 * object can be retrieved.
 */
@Service()
public class GMSAdapterService implements Startup, PostConstruct, ConfigListener {

    final static Logger logger = LogDomains.getLogger(
        GMSAdapterService.class, LogDomains.CORE_LOGGER);

    private static final StringManager strings =
        StringManager.getManager(GMSAdapterService.class);

    private static final String GMS_ENABLED = "GMS_ENABLED";
    private static final String SEED_LIST = "GMS_" +
        ServiceProviderConfigurationKeys.DISCOVERY_URI_LIST;
    private static final String CLUSTER_NAME_PROPERTY = "cluster-name";

    @Inject
    Clusters clusters;

    @Inject(name=ServerEnvironment.DEFAULT_INSTANCE_NAME)
    Server server;

    @Inject
    ServerEnvironment env;

    @Inject
    Habitat habitat;

    @Inject
    StartupContext startupContext;

    static private final Object lock = new Object();

    List<GMSAdapter> gmsAdapters = new LinkedList<GMSAdapter>();
    final static private Level TRACE_LEVEL = Level.FINE;

    /**
     * Returns the lifecyle of the service. This service may not be needed
     * after startup -- we still need to determine how to load GMS when
     * a gms-enabled cluster is first created during runtime.
     * TODO: determine SERVER v START
     */
    @Override
    public Startup.Lifecycle getLifecycle() {
        return Startup.Lifecycle.SERVER;
    }

    /**
     * Starts the application loader service.
     */
    @Override
    public void postConstruct() {
        // first check that this isn't a config upgrade
        if (startupContext != null) {
            Properties args = startupContext.getArguments();
            if (args != null && Boolean.valueOf(args.getProperty("-upgrade"))) {
                return;
            }
        }

        // in the UMC case, check server-config, otherwise check clusters
        if (server.isClusteredDas()) {
            logger.setLevel(TRACE_LEVEL);
            logger.log(TRACE_LEVEL, "Turning on trace logging during " +
                "development. Will remove this once we're stable.");
            checkServerConfig(server.getConfig());
        } else if (clusters != null) {
            if (env.isDas()) {
                checkAllClusters(clusters);
            } else {
                Cluster cluster = server.getCluster();
                if (cluster != null) {
                    checkCluster(cluster);
                }
            }
        }
    }

    @Override
    public String toString() {
        return "GMS Loader";
    }

    /*
     */
    public GMSAdapter getGMSAdapter() {
        synchronized(lock) {
            if (gmsAdapters.size() > 1) {
                throw new IllegalStateException(
                    strings.getString("use.getByName"));
            } else if (gmsAdapters.size() == 1) {
                return gmsAdapters.get(0);
            } else {
                return null;
            }
        }
    }

    public boolean isGmsEnabled() {
        return gmsAdapters.size() > 0;
    }

    public GMSAdapter getGMSAdapterByName(String clusterName) {
        synchronized(lock) {
            return habitat.getComponent(GMSAdapter.class, clusterName);
        }
    }

    /**
     * Create a GMSAdapter for each cluster that has gms enabled.
     */
    private void checkAllClusters(Clusters clusters) {
        if (logger.isLoggable(TRACE_LEVEL)) {
            logger.log(TRACE_LEVEL, "In DAS. Checking all clusters.");
        }
        for (Cluster cluster : clusters.getCluster()) {
            checkCluster(cluster);
        }
    }

    private GMSAdapter checkCluster(Cluster cluster) {
        GMSAdapter result = null;
        String gmsEnString = cluster.getGmsEnabled();
        if (logger.isLoggable(TRACE_LEVEL)) {
            logger.log(TRACE_LEVEL, String.format("cluster %s found with gms-enabled='%s'",
                        cluster.getName(), gmsEnString));
        }
        if (gmsEnString != null && Boolean.parseBoolean(gmsEnString)) {
            result = loadModule(cluster.getName());
        }
        return result;
    }

    /*
     * In this iteration, will only check for the "seed list," implying
     * that multicast is not available. In a future version we can also
     * check for multicast address and port.
     *
     * If the seed list is null, we'll warn and exit. An empty list is
     * ok, but null could mean the user forgot to set it. When we're supporting
     * UMC with nonmulticast and multicast, something must be set to tell
     * GMS which mode to use.
     *
     * This is for the UMC case only.
     */
    private void checkServerConfig(Config config) {
        com.sun.enterprise.config.serverbeans.GroupManagementService gms =
            config.getGroupManagementService();
        boolean gmsEnabled = false;
        String seedList = null;
        for (Property prop : gms.getProperty()) {
            if (GMS_ENABLED.equals(prop.getName())) {
                gmsEnabled = Boolean.valueOf(prop.getValue());
            } else if (SEED_LIST.equals(prop.getName())) {
                seedList = prop.getValue();
            }
        }
        if (gmsEnabled) {
            if (seedList == null) {
                logger.log(Level.WARNING, "gmsadapter.null.seedlist");
                return;
            }
            String clusterName = server.getPropertyValue(CLUSTER_NAME_PROPERTY);
            if (clusterName == null || clusterName.isEmpty()) {
                logger.log(Level.WARNING, "gmsadapter.null.clustername");
                return;
            }
            loadModule(clusterName);
        }
    }

    /*
     * Initial support for multiple clusters in DAS. A clustered instance can
     * only belong to one cluster. In the UMC case, there will only be
     * one cluster at all.
     */
    private GMSAdapter loadModule(String name) {
        GMSAdapter result = null;
        synchronized(lock) {
            result = getGMSAdapterByName(name);
            if (logger.isLoggable(TRACE_LEVEL)) {
                logger.log(TRACE_LEVEL, "lookup GMSAdapter by clusterName=" +
                    name + " returned " + result);
            }
            if (result == null) {
                if (logger.isLoggable(TRACE_LEVEL)) {
                    logger.log(TRACE_LEVEL,
                        "creating gms-adapter for clustername " + name +
                            " since no gms adapter found for clustername " +
                            name);
                }
                result = habitat.getByContract(GMSAdapter.class);

                // see https://glassfish.dev.java.net/issues/show_bug.cgi?id=12850
                if (result == null) {
                    logger.log(Level.WARNING, "gmsadapter.not.available");
                    return null;
                }
                boolean initResult = result.initialize(name);
                if (initResult == false) {
                    return null;
                }
                habitat.addIndex(
                    new ExistingSingletonInhabitant<GMSAdapter>(result),
                    GMSAdapter.class.getName(), name);
                if (logger.isLoggable(TRACE_LEVEL)) {
                    logger.log(TRACE_LEVEL,
                        "loadModule: registered created gmsadapter for cluster " +
                            name + " initialized result=" + initResult);
                }
                gmsAdapters.add(result);
            }
        }
        return result;
    }

    /*
     * On create-cluster event, DAS joins a gms-enabled cluster.
     * On delete-cluster event, DAS leaves a gms-enabled cluster.
     */
    @Override
    public UnprocessedChangeEvents changed(PropertyChangeEvent[] events) {
        if (env.isDas()) {
            return ConfigSupport.sortAndDispatch(events, new Changed() {
                @Override
                public <T extends ConfigBeanProxy> NotProcessed changed(TYPE type, Class<T> changedType, T changedInstance) {
                    if (changedType == Cluster.class && type == TYPE.ADD) {  //create-cluster
                        Cluster cluster = (Cluster) changedInstance;
                        if (logger.isLoggable(TRACE_LEVEL)) {
                            logger.log(TRACE_LEVEL, "ClusterChangeEvent add cluster " + cluster.getName());
                        }
                        GMSAdapter localGmsAdapter = checkCluster(cluster);
                        if (localGmsAdapter != null) {
                            GroupManagementService gms = localGmsAdapter.getModule();
                            if (gms != null) {
                                gms.reportJoinedAndReadyState();
                            }
                        }

                        // todo:  when supporting multiple clusters, ensure that newly added cluster has a different gms-multicast-address than all existing clusters.
                        //        currently, generating a unique multicast address depending on random so this check is necessary.
                    }
                    if (changedType == Cluster.class && type == TYPE.REMOVE) {  //remove-cluster
                        Cluster cluster = (Cluster) changedInstance;
                        if (logger.isLoggable(TRACE_LEVEL)) {
                            logger.log(TRACE_LEVEL, "ClusterChangeEvent remove cluster " + cluster.getName());
                        }
                        synchronized(lock) {
                            GMSAdapter localGmsAdapter = getGMSAdapterByName(cluster.getName());
                            if (localGmsAdapter != null) {
                                gmsAdapters.remove(localGmsAdapter);
                                localGmsAdapter.getModule().shutdown(GMSConstants.shutdownType.INSTANCE_SHUTDOWN);
                                boolean result = habitat.removeIndex(GMSAdapter.class.getName(), localGmsAdapter);
                                if (logger.isLoggable(TRACE_LEVEL)) {
                                    logger.log(TRACE_LEVEL, "removeIndex(" + GMSAdapter.class.getName() + ") returned result of " + result);
                                }

                                // remove GMS module for deleted cluster.  Must do this or will fail if the cluster is recreated before DAS is stopped.
                                localGmsAdapter.complete();
                            }
                        }
                    }
                    return null;
                }
            }, logger);
        }
        return null;
    }
}