Metacat

/**

 *  '$RCSfile$'

 *    Purpose: Implements a service for managing a Hazelcast cluster member

 *  Copyright: 2011 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Christopher Jones

 * 

 *   '$Author: cjones $'

 *     '$Date: 2012-11-10 15:34:51 -0800 (Sat, 10 Nov 2012) $'

 * '$Revision: 7421 $'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.dataone.hazelcast;

import java.io.FileNotFoundException;

import java.sql.SQLException;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.Set;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.locks.Lock;

import org.apache.log4j.Logger;

import org.dataone.service.exceptions.InvalidSystemMetadata;

import org.dataone.service.types.v1.Identifier;

import org.dataone.service.types.v1.Node;

import org.dataone.service.types.v1.NodeReference;

import org.dataone.service.types.v1.SystemMetadata;

import com.hazelcast.config.Config;

import com.hazelcast.config.FileSystemXmlConfig;

import com.hazelcast.core.EntryEvent;

import com.hazelcast.core.EntryListener;

import com.hazelcast.core.Hazelcast;

import com.hazelcast.core.HazelcastInstance;

import com.hazelcast.core.ILock;

import com.hazelcast.core.IMap;

import com.hazelcast.core.ISet;

import com.hazelcast.core.ItemEvent;

import com.hazelcast.core.ItemListener;

import com.hazelcast.core.LifecycleEvent;

import com.hazelcast.core.LifecycleListener;

import com.hazelcast.core.Member;

import com.hazelcast.core.MembershipEvent;

import com.hazelcast.core.MembershipListener;

import com.hazelcast.partition.Partition;

import com.hazelcast.partition.PartitionService;

import edu.ucsb.nceas.metacat.IdentifierManager;

import edu.ucsb.nceas.metacat.McdbDocNotFoundException;

import edu.ucsb.nceas.metacat.properties.PropertyService;

import edu.ucsb.nceas.metacat.shared.BaseService;

import edu.ucsb.nceas.metacat.shared.ServiceException;

import edu.ucsb.nceas.metacat.util.DocumentUtil;

import edu.ucsb.nceas.utilities.FileUtil;

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

/**

 * The Hazelcast service enables Metacat as a Hazelcast cluster member

 */

public class HazelcastService extends BaseService

  implements EntryListener<Identifier, SystemMetadata>, MembershipListener, LifecycleListener, ItemListener<Identifier> {

  private static final String SINCE_PROPERTY = "dateSysMetadataModified";

  private static final String MISSING_PID_PREFIX = "missing-";

/* The instance of the logging class */

  private static Logger logMetacat = Logger.getLogger(HazelcastService.class);

  /* The singleton instance of the hazelcast service */

  private static HazelcastService hzService = null;

  /* The Hazelcast configuration */

  private Config hzConfig;

  /* The name of the system metadata map */

  private String systemMetadataMap;

  /* The Hazelcast distributed system metadata map */

  private IMap<Identifier, SystemMetadata> systemMetadata;

  /* The name of the identifiers set */

  private String identifiersSet;

  /* The Hazelcast distributed identifiers set */

  private ISet<Identifier> identifiers;

  /* The Hazelcast distributed missing identifiers set */

  private ISet<Identifier> missingIdentifiers;

  private HazelcastInstance hzInstance;

  /*

   * Constructor: Creates an instance of the hazelcast service. Since

   * this uses a singleton pattern, use getInstance() to gain the instance.

   */

  private HazelcastService() {

    super();

    _serviceName="HazelcastService";

    try {

      init();

    } catch (ServiceException se) {

      logMetacat.error("There was a problem creating the HazelcastService. " +

                       "The error message was: " + se.getMessage());

    }

  }

  /**

   *  Get the instance of the HazelcastService that has been instantiated,

   *  or instantiate one if it has not been already.

   *

   * @return hazelcastService - The instance of the hazelcast service

   */

  public static HazelcastService getInstance(){

    if ( hzService == null ) {

      hzService = new HazelcastService();

    }

    return hzService;

  }

  /**

   * Initializes the Hazelcast service

   */

  public void init() throws ServiceException {

    logMetacat.debug("HazelcastService.init() called.");

	String configFileName = null;

	try {

		configFileName = PropertyService.getProperty("dataone.hazelcast.configFilePath");

		hzConfig = new FileSystemXmlConfig(configFileName);

	} catch (Exception e) {

		configFileName = PropertyService.CONFIG_FILE_DIR + FileUtil.getFS() + "hazelcast.xml";

		logMetacat.warn("Custom Hazelcast configuration not defined, using default: " + configFileName);

		// make sure we have the config

		try {

			hzConfig = new FileSystemXmlConfig(configFileName);

		} catch (FileNotFoundException e1) {

			String msg = e.getMessage();

			logMetacat.error(msg);

			throw new ServiceException(msg);

		}

	}

	this.hzInstance = Hazelcast.newHazelcastInstance(hzConfig);

  	logMetacat.debug("Initialized hzInstance");

    // Get configuration properties on instantiation

    try {

      systemMetadataMap = 

        PropertyService.getProperty("dataone.hazelcast.storageCluster.systemMetadataMap");

      identifiersSet = PropertyService.getProperty("dataone.hazelcast.storageCluster.identifiersSet");

      // Get a reference to the shared system metadata map as a cluster member

      // NOTE: this loads the map from the backing store and can take a long time for large collections

      systemMetadata = this.hzInstance.getMap(systemMetadataMap);

      logMetacat.debug("Initialized systemMetadata");

      // Get a reference to the shared identifiers set as a cluster member

      // NOTE: this takes a long time to complete

      logMetacat.warn("Retrieving hzIdentifiers from Hazelcast");

      identifiers = this.hzInstance.getSet(identifiersSet);

      logMetacat.warn("Retrieved hzIdentifiers from Hazelcast");

      // for publishing the "PIDs Wanted" list

      missingIdentifiers = this.hzInstance.getSet("hzMissingIdentifiersSet");

      missingIdentifiers.addItemListener(this, true);

      // Listen for changes to the system metadata map

      systemMetadata.addEntryListener(this, true);

      // Listen for members added/removed

      hzInstance.getCluster().addMembershipListener(this);

      // Listen for lifecycle state changes

      hzInstance.getLifecycleService().addLifecycleListener(this);

    } catch (PropertyNotFoundException e) {

      String msg = "Couldn't find Hazelcast properties for the DataONE clusters. " +

        "The error message was: " + e.getMessage();

      logMetacat.error(msg);

    }

    // make sure we have all metadata locally

    try {

    	// synch on restart

        resynchInThread();

	} catch (Exception e) {

		String msg = "Problem resynchronizing system metadata. " + e.getMessage();

		logMetacat.error(msg, e);

	}

  }

  /**

   * Get the system metadata map

   * 

   * @return systemMetadata - the hazelcast map of system metadata

   * @param identifier - the identifier of the object as a string

   */

  public IMap<Identifier,SystemMetadata> getSystemMetadataMap() {

	  return systemMetadata;

  }

  /**

   * Get the identifiers set

   * @return identifiers - the set of unique DataONE identifiers in the cluster

   */

  public ISet<Identifier> getIdentifiers() {

      return identifiers;

  }

  /**

   * When Metacat changes the underlying store, we need to refresh the

   * in-memory representation of it.

   * @param guid

   */

  public void refreshSystemMetadataEntry(String guid) {

	Identifier identifier = new Identifier();

	identifier.setValue(guid);

	// force hazelcast to update system metadata in memory from the store

	HazelcastService.getInstance().getSystemMetadataMap().evict(identifier);

  }

  public Lock getLock(String identifier) {

    Lock lock = null;

    try {

        lock = getInstance().getHazelcastInstance().getLock(identifier);

    } catch (RuntimeException e) {

        logMetacat.info("Couldn't get a lock for identifier " + 

            identifier + " !!");

    }

    return lock;

  }

  /**

   * Get the DataONE hazelcast node map

   * @return nodes - the hazelcast map of nodes

   */

//  public IMap<NodeReference, Node> getNodesMap() {

//	  return nodes;

//  }

  /**

   * Indicate whether or not this service is refreshable.

   *

   * @return refreshable - the boolean refreshable status

   */

  public boolean refreshable() {

    // TODO: Determine the consequences of restarting the Hazelcast instance

    // Set this to true if it's okay to drop from the cluster, lose the maps,

    // and start back up again

    return false;

  }

  /**

   * Stop the HazelcastService. When stopped, the service will no longer

   * respond to requests.

   */

  public void stop() throws ServiceException {

	  this.hzInstance.getLifecycleService().shutdown();

  }

  public HazelcastInstance getHazelcastInstance() {

      return this.hzInstance;

  }

  /**

   * Refresh the Hazelcast service by restarting it

   */

  @Override

  protected void doRefresh() throws ServiceException {

    // TODO: verify that the correct config file is still used

	  this.hzInstance.getLifecycleService().restart();

  }

  /**

	 * Implement the EntryListener interface for Hazelcast, reponding to entry

	 * added events in the hzSystemMetadata map. Evaluate the entry and create

	 * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

	 * 

	 * @param event - The EntryEvent that occurred

	 */

	@Override

	public void entryAdded(EntryEvent<Identifier, SystemMetadata> event) {

	  logMetacat.info("SystemMetadata entry added event on identifier " + 

	      event.getKey().getValue());

		// handle as update - that method will create if necessary

		entryUpdated(event);

	}

	/**

	 * Implement the EntryListener interface for Hazelcast, reponding to entry

	 * evicted events in the hzSystemMetadata map.  Evaluate the entry and create

	 * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

	 * 

	 * @param event - The EntryEvent that occurred

	 */

	@Override

	public void entryEvicted(EntryEvent<Identifier, SystemMetadata> event) {

      logMetacat.info("SystemMetadata entry evicted event on identifier " + 

          event.getKey().getValue());

	    // ensure identifiers are listed in the hzIdentifiers set

      if ( !identifiers.contains(event.getKey()) ) {

          identifiers.add(event.getKey());

      }

	}

	/**

	 * Implement the EntryListener interface for Hazelcast, reponding to entry

	 * removed events in the hzSystemMetadata map.  Evaluate the entry and create

	 * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

	 * 

	 * @param event - The EntryEvent that occurred

	 */

	@Override

	public void entryRemoved(EntryEvent<Identifier, SystemMetadata> event) {

    logMetacat.info("SystemMetadata entry removed event on identifier " + 

        event.getKey().getValue());

	  // we typically don't remove objects in Metacat, but can remove System Metadata

		IdentifierManager.getInstance().deleteSystemMetadata(event.getValue().getIdentifier().getValue());

    // keep the hzIdentifiers set in sync with the systemmetadata table

    if ( identifiers.contains(event.getKey()) ) {

        identifiers.remove(event.getKey());

    }

	}

	/**

	 * Implement the EntryListener interface for Hazelcast, reponding to entry

	 * updated events in the hzSystemMetadata map.  Evaluate the entry and create

	 * CNReplicationTasks as appropriate (for DATA, METADATA, RESOURCE)

	 * 

	 * @param event - The EntryEvent that occurred

	 */

	@Override

	public void entryUpdated(EntryEvent<Identifier, SystemMetadata> event) {

		logMetacat.debug("Entry added/updated to System Metadata map: " + event.getKey().getValue());

		PartitionService partitionService = this.hzInstance.getPartitionService();

		Partition partition = partitionService.getPartition(event.getKey());

		Member ownerMember = partition.getOwner();

		SystemMetadata sysmeta = event.getValue();

		if (!ownerMember.localMember()) {

			if (sysmeta == null) {

				logMetacat.warn("No SystemMetadata provided in the event, getting from shared map: " + event.getKey().getValue());

				sysmeta = getSystemMetadataMap().get(event.getKey());

				if (sysmeta == null) {

					// this is a problem

					logMetacat.error("Could not find SystemMetadata in shared map for: " + event.getKey().getValue());

					// TODO: should probably return at this point since the save will fail

				}

			}

			// need to pull the entry into the local store

			saveLocally(event.getValue());

		}

		// ensure identifiers are listed in the hzIdentifiers set

		if (!identifiers.contains(event.getKey())) {

			identifiers.add(event.getKey());

		}

	}

	/**

	 * Save SystemMetadata to local store if needed

	 * @param sm

	 */

	private void saveLocally(SystemMetadata sm) {

		logMetacat.debug("Saving entry locally: " + sm.getIdentifier().getValue());

		try {

			IdentifierManager.getInstance().insertOrUpdateSystemMetadata(sm);

		} catch (McdbDocNotFoundException e) {

			logMetacat.error("Could not save System Metadata to local store.", e);

		} catch (SQLException e) {

	      logMetacat.error("Could not save System Metadata to local store.", e);

	    } catch (InvalidSystemMetadata e) {

	        logMetacat.error("Could not save System Metadata to local store.", e);

	    }

	}

	/**

	 * Checks the local backing store for missing SystemMetadata,

	 * retrieves those entries from the shared map if they exist,

	 * and saves them locally.

	 */

	private void synchronizeLocalStore() {

		List<String> localIds = IdentifierManager.getInstance().getLocalIdsWithNoSystemMetadata(true, -1);

		if (localIds != null) {

			logMetacat.debug("Member missing SystemMetadata entries, count = " + localIds.size());

			for (String localId: localIds) {

				logMetacat.debug("Processing system metadata for localId: " + localId);

				try {

					String docid = DocumentUtil.getSmartDocId(localId);

					int rev = DocumentUtil.getRevisionFromAccessionNumber(localId);

					String guid = IdentifierManager.getInstance().getGUID(docid, rev);

					logMetacat.debug("Found mapped guid: " + guid);

					Identifier pid = new Identifier();

					pid.setValue(guid);

					SystemMetadata sm = systemMetadata.get(pid);

					logMetacat.debug("Found shared system metadata for guid: " + guid);

					saveLocally(sm);

					logMetacat.debug("Saved shared system metadata locally for guid: " + guid);

				} catch (Exception e) {

					logMetacat.error("Could not save shared SystemMetadata entry locally, localId: " + localId, e);

				}

			}

		}

	}

	/**

	 * Make sure we have a copy of every entry in the shared map.

	 * We use lazy loading and therefore the CNs may not all be in sync when one

	 * comes back online after an extended period of being offline

	 * This method loops through the entries that a FULLY UP-TO-DATE CN has

	 * and makes sure each one is present on the shared map.

	 * It is meant to overcome a HZ weakness wherein ownership of a key results in 

	 * null values where the owner does not have a complete backing store.

	 * This will be an expensive routine and should be run in a background process so that

	 * the server can continue to service other requests during the synch

	 * @throws Exception

	 */

	private void resynchToRemote() {

		// the local identifiers not already present in the shared map

		Set<Identifier> localIdKeys = loadAllKeys();

		//  the PIDs missing locally

		Set<Identifier> missingIdKeys = new HashSet<Identifier>();

		// only contribute PIDs that are not already shared

		Iterator<Identifier> idIter = identifiers.iterator();

		int processedCount = 0;

		while (idIter.hasNext()) {

			Identifier pid = idIter.next();

			if (localIdKeys.contains(pid)) {

				logMetacat.debug("Shared pid is already in local identifier set: " + pid.getValue());

				localIdKeys.remove(pid);

			} else {

				// we don't have this locally, so we should try to get it

				missingIdKeys.add(pid);

			}

			processedCount++;

		}

		logMetacat.warn("processedCount (identifiers from iterator): " + processedCount);

		logMetacat.warn("local pid count not yet shared: " + localIdKeys.size() + ", shared pid count: " + identifiers.size());

		//identifiers.addAll(idKeys);

		logMetacat.warn("Loading missing local keys into hzIdentifiers");

		for (Identifier key: localIdKeys) {

			if (!identifiers.contains(key)) {

				logMetacat.debug("Adding missing hzIdentifiers key: " + key.getValue());

				identifiers.add(key);

			}

		}

		logMetacat.warn("Initialized identifiers with missing local keys");

		logMetacat.warn("Processing missing SystemMetadata for missing pid count: " + missingIdKeys.size());

		// loop through all the missing PIDs to find any null (missing) SM that needs to be resynched

		Iterator<Identifier> missingPids = missingIdKeys.iterator();

		while (missingPids.hasNext()) {

			Identifier pid = missingPids.next();

			// publish that we need this SM entry

			logMetacat.debug("Publishing missing pid to wanted list: " + pid.getValue());

			missingIdentifiers.add(pid);

		}

	}

	public void resynchInThread() {

		logMetacat.debug("launching system metadata resynch in a thread");

		ExecutorService executor = Executors.newSingleThreadExecutor();

		executor.execute(new Runnable() {

			@Override

			public void run() {

				try {

					// this is a push mechanism

					resynchToRemote();

				} catch (Exception e) {

					logMetacat.error("Error in resynchInThread: " + e.getMessage(), e);

				}

			}

		});

		executor.shutdown();

	}

	/**

	 * When there is missing SystemMetadata on the local member,

	 * we retrieve it from the shared map and add it to the local

	 * backing store for safe keeping.

	 */

	@Override

	public void memberAdded(MembershipEvent event) {

		Member member = event.getMember();

		logMetacat.debug("Member added to cluster: " + member.getInetSocketAddress());

		boolean isLocal = member.localMember();

		if (isLocal) {

			logMetacat.debug("Member islocal: " + member.getInetSocketAddress());

			synchronizeLocalStore();

		}

	}

	@Override

	public void memberRemoved(MembershipEvent event) {

		// TODO Auto-generated method stub

	}

	/**

	 * In cases where this cluster is paused, we want to 

	 * check that the local store accurately reflects the shared 

	 * SystemMetadata map

	 * @param event

	 */

	@Override

	public void stateChanged(LifecycleEvent event) {

		logMetacat.debug("HZ LifecycleEvent.state: " + event.getState());

		if (event.getState().equals(LifecycleEvent.LifecycleState.RESUMED)) {

			logMetacat.debug("HZ LifecycleEvent.state is RESUMED, calling synchronizeLocalStore()");

			synchronizeLocalStore();

		}

	}

	/**

	 * Load all System Metadata keys from the backing store

	 * @return set of pids

	 */

	private Set<Identifier> loadAllKeys() {

		Set<Identifier> pids = new HashSet<Identifier>();

		try {

			// ALTERNATIVE 1: this has more overhead than just looking at the GUIDs

//			ObjectList ol = IdentifierManager.getInstance().querySystemMetadata(

//					null, //startTime, 

//					null, //endTime, 

//					null, //objectFormatId, 

//					false, //replicaStatus, 

//					0, //start, 

//					-1 //count

//					);

//			for (ObjectInfo o: ol.getObjectInfoList()) {

//				Identifier pid = o.getIdentifier();

//				if ( !pids.contains(pid) ) {

//					pids.add(pid);

//				}				

//			}

			// ALTERNATIVE method: look up all the Identifiers from the table

			List<String> guids = IdentifierManager.getInstance().getAllSystemMetadataGUIDs();

			logMetacat.warn("Local SystemMetadata pid count: " + guids.size());

			for (String guid: guids){

				Identifier pid = new Identifier();

				pid.setValue(guid);

				pids.add(pid);

			}

		} catch (Exception e) {

			throw new RuntimeException(e.getMessage(), e);

		}

		return pids;

	}

	/**

	 * Respond to itemAdded events on the hzMissingIdentifiers Set.  Uses a

	 * distributed ILock to try to prevent multiple put calls on hzSystemMetadata

	 * 

	 * @param pid   the identifier of the event

	 */

	@Override

	public void itemAdded(ItemEvent<Identifier> event) {

		Identifier pid = (Identifier) event.getItem();

		// publish the SM for the pid if we have it locally

		logMetacat.debug("Responding to itemAdded for pid: " + pid.getValue());

		// lock this event, only if we have a local copy to contribute

		ILock lock = null;

		try {

			// look up the local copy of the SM

			SystemMetadata sm = IdentifierManager.getInstance().getSystemMetadata(pid.getValue());

			if (sm != null) {

				lock = hzInstance.getLock(MISSING_PID_PREFIX + pid.getValue());

				if ( lock.tryLock() ) {

			        // "publish" the system metadata to the shared map since it showed up on the missing queue

			        logMetacat.debug("Adding SystemMetadata to shared map for pid: " + pid.getValue());

			        systemMetadata.put(pid, sm);

			        // remove the entry since we processed it

			        missingIdentifiers.remove(pid);

				  } else {

				      logMetacat.debug(MISSING_PID_PREFIX + pid.getValue() + " was already locked. Skipping.");

				  }

			} else {

				// can't help here

				logMetacat.warn("Local system metadata not found for pid: " + pid.getValue());

			}

		} catch (Exception e) {

			logMetacat.error("Error looking up missing system metadata for pid: " + pid.getValue());

		} finally {

			if ( lock != null ) {

				lock.unlock();

			}

        }

	}

	/**

   * Respond to itemRemoved events on the hzMissingIdentifiers Set

   * 

   * @param pid   the identifier of the event

   */

	@Override

	public void itemRemoved(ItemEvent<Identifier> event) {

		// do nothing since someone probably handled the wanted PID

	}

}