Java tutorial
/***************************************************************************** * * Copyright (C) Zenoss, Inc. 2010, 2014, all rights reserved. * * This content is made available according to terms specified in * License.zenoss under the directory where your Zenoss product is installed. * ****************************************************************************/ package org.zenoss.zep.index.impl; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.scheduling.TaskScheduler; import org.zenoss.protobufs.zep.Zep.*; import org.zenoss.zep.Messages; import org.zenoss.zep.UUIDGenerator; import org.zenoss.zep.ZepException; import org.zenoss.zep.impl.ThreadRenamingRunnable; import org.zenoss.zep.index.EventIndexDao; import org.zenoss.zep.index.SavedSearchProcessor; import java.io.IOException; import java.util.Date; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.TimeUnit; public abstract class BaseEventIndexDaoImpl<SS extends SavedSearch> implements EventIndexDao { private final String name; private final Messages messages; private final TaskScheduler scheduler; private final UUIDGenerator uuidGenerator; private final Map<String, SS> savedSearches = new ConcurrentHashMap<String, SS>(); protected static final Logger logger = LoggerFactory.getLogger(EventIndexDao.class); public BaseEventIndexDaoImpl(String name, Messages messages, TaskScheduler scheduler, UUIDGenerator uuidGenerator) { this.name = name; this.messages = messages; this.scheduler = scheduler; this.uuidGenerator = uuidGenerator; } @Override public final String getName() { return this.name; } public void purge(int duration, TimeUnit unit) throws ZepException { if (duration < 0) { throw new IllegalArgumentException("Duration must be >= 0"); } final Date threshold = new Date(System.currentTimeMillis() - unit.toMillis(duration)); logger.info("Purging events older than {}", threshold); purge(threshold); commit(); } /** * Delete all events prior to the given threshold. * * @param threshold * @throws ZepException */ protected abstract void purge(Date threshold) throws ZepException; @Override public void stage(EventSummary event) throws ZepException { index(event); } @Override public void stageDelete(String uuid) throws ZepException { delete(uuid); } @Override @Deprecated public final void commit(boolean forceOptimize) throws ZepException { commit(); } public void shutdown() { deleteAllSavedSearches(); } protected String generateUuid() { return uuidGenerator.generate().toString(); } @Override public String createSavedSearch(EventQuery eventQuery) throws ZepException { if (eventQuery.getTimeout() < 1) { throw new ZepException("Invalid timeout: " + eventQuery.getTimeout()); } final String uuid = generateUuid(); SS search = null; try { search = buildSavedSearch(uuid, eventQuery); savedSearches.put(uuid, search); scheduleSearchTimeout(search); } catch (Exception e) { logger.warn("Exception while creating saved search", e); deleteSavedSearch(uuid); if (search != null) { try { search.close(); } catch (IOException ioe) { logger.warn("Exception while closing saved search", e); } } if (e instanceof ZepException) { throw (ZepException) e; } throw new ZepException(e); } return uuid; } protected EventSummaryResult savedSearchInternal(String uuid, int offset, int limit, SavedSearchProcessor<SS> processor) throws ZepException { final SS search = savedSearches.get(uuid); if (search == null) { throw new ZepException(messages.getMessage("saved_search_not_found", uuid)); } try { /* Cancel the timeout for the saved search to prevent it expiring while in use */ cancelSearchTimeout(search); return processor.result(search, offset, limit); } finally { scheduleSearchTimeout(search); } } @Override public EventSummaryResult savedSearch(String uuid, int offset, int limit) throws ZepException { return savedSearchInternal(uuid, offset, limit, savedSearchProcessor()); } @Override public EventSummaryResult savedSearchUuids(String uuid, int offset, int limit) throws ZepException { return savedSearchInternal(uuid, offset, limit, savedSearchUuidsProcessor()); } protected void deleteAllSavedSearches() { while (!savedSearches.isEmpty()) { for (String uuid : savedSearches.keySet()) { SS search = savedSearches.remove(uuid); if (search != null) { cancelSearchTimeout(search); try { search.close(); } catch (IOException e) { logger.warn("Exception while closing saved search", e); } } } } } @Override public String deleteSavedSearch(String uuid) throws ZepException { final SS search = savedSearches.remove(uuid); if (search == null) { return null; } logger.debug("Deleting saved search: {}", uuid); cancelSearchTimeout(search); try { search.close(); } catch (IOException e) { throw new ZepException(e); } return search.getUuid(); } private void cancelSearchTimeout(final SS search) { logger.debug("Canceling timeout for saved search: {}", search.getUuid()); search.setTimeoutFuture(null); } private void scheduleSearchTimeout(final SS search) { logger.debug("Scheduling saved search {} for expiration in {} seconds", search.getUuid(), search.getTimeout()); Date d = new Date(System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(search.getTimeout())); search.setTimeoutFuture(scheduler.schedule(new ThreadRenamingRunnable(new Runnable() { @Override public void run() { logger.debug("Saved search timed out: {}", search.getUuid()); savedSearches.remove(search.getUuid()); try { search.close(); } catch (IOException e) { logger.warn("Exception while closing saved search", e); } } }, "ZEP_SAVED_SEARCH_TIMEOUT"), d)); } protected abstract SS buildSavedSearch(String uuid, EventQuery eventQuery) throws ZepException; protected abstract SavedSearchProcessor<SS> savedSearchProcessor(); protected abstract SavedSearchProcessor<SS> savedSearchUuidsProcessor(); }