Java tutorial
/* COPYRIGHT STATUS: Dec 1st 2001, Fermi National Accelerator Laboratory (FNAL) documents and software are sponsored by the U.S. Department of Energy under Contract No. DE-AC02-76CH03000. Therefore, the U.S. Government retains a world-wide non-exclusive, royalty-free license to publish or reproduce these documents and software for U.S. Government purposes. All documents and software available from this server are protected under the U.S. and Foreign Copyright Laws, and FNAL reserves all rights. Distribution of the software available from this server is free of charge subject to the user following the terms of the Fermitools Software Legal Information. Redistribution and/or modification of the software shall be accompanied by the Fermitools Software Legal Information (including the copyright notice). The user is asked to feed back problems, benefits, and/or suggestions about the software to the Fermilab Software Providers. 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Anyone downloading information from this server is obligated to secure any necessary Government licenses before exporting documents or software obtained from this server. */ package org.dcache.alarms.dao.impl; import com.google.common.collect.Iterables; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.jdo.FetchPlan; import javax.jdo.JDOException; import javax.jdo.PersistenceManager; import javax.jdo.PersistenceManagerFactory; import javax.jdo.Query; import javax.jdo.Transaction; import java.util.Collection; import java.util.Collections; import java.util.Date; import java.util.HashMap; import java.util.Map; import java.util.concurrent.TimeUnit; import org.dcache.alarms.LogEntry; import org.dcache.alarms.dao.AlarmJDOUtils; import org.dcache.alarms.dao.AlarmJDOUtils.AlarmDAOFilter; import org.dcache.alarms.dao.LogEntryDAO; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkNotNull; /** * DataNucleus wrapper to underlying alarm store.<br> * <br> */ public final class DataNucleusLogEntryStore implements LogEntryDAO, Runnable { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final PersistenceManagerFactory pmf; /** * Optional cleaner daemon. */ private boolean cleanerEnabled; private int cleanerSleepInterval; private TimeUnit cleanerSleepIntervalUnit; private int cleanerDeleteThreshold; private TimeUnit cleanerDeleteThresholdUnit; private Thread cleanerThread; public DataNucleusLogEntryStore(PersistenceManagerFactory pmf) { this.pmf = pmf; } @Override public Collection<LogEntry> get(AlarmDAOFilter filter) { PersistenceManager readManager = pmf.getPersistenceManager(); if (readManager == null) { return Collections.emptyList(); } Transaction tx = readManager.currentTransaction(); try { tx.begin(); Collection<LogEntry> result = AlarmJDOUtils.execute(readManager, filter); logger.debug("got collection {}", result); Collection<LogEntry> detached = readManager.detachCopyAll(result); logger.debug("got detatched collection {}", detached); tx.commit(); logger.debug("successfully executed get for filter {}", filter); return detached; } catch (JDOException t) { logJDOException("get", filter, t); return Collections.emptyList(); } finally { try { AlarmJDOUtils.rollbackIfActive(tx); } finally { readManager.close(); } } } public void initialize() { if (cleanerEnabled) { if (cleanerThread != null && cleanerThread.isAlive()) { return; } checkArgument(cleanerSleepInterval > 0); checkArgument(cleanerDeleteThreshold > 0); cleanerThread = new Thread(this, "alarm-cleanup-daemon"); cleanerThread.start(); } } public boolean isConnected() { return pmf != null && pmf.getPersistenceManager() != null; } @Override public void put(LogEntry entry) { PersistenceManager insertManager = pmf.getPersistenceManager(); try { Transaction tx = insertManager.currentTransaction(); tx.begin(); try { Query query = insertManager.newQuery(LogEntry.class); query.setFilter("key==k"); query.declareParameters("java.lang.String k"); query.addExtension("datanucleus.query.resultCacheType", "none"); query.getFetchPlan().setFetchSize(FetchPlan.FETCH_SIZE_OPTIMAL); Collection<LogEntry> dup = (Collection<LogEntry>) query.executeWithArray(entry.getKey()); logger.trace("duplicate? {}", dup); if (dup != null && !dup.isEmpty()) { if (dup.size() > 1) { throw new RuntimeException("data store inconsistency!" + " more than one alarm with the same id: " + entry.getKey()); } LogEntry original = dup.iterator().next(); entry.setLastUpdate(original.getLastUpdate()); int received = original.getReceived(); if (original.isClosed()) { /* * this needs to be done or else newly arriving instances will * not be tracked if this type has been closed previously */ original.setClosed(false); /* * Treat the alarm as a new instance by restarting * its history. This guarantees a new alert will * be sent and plugins called as if it were a * first occurrence. */ received = 1; } else { ++received; } original.setReceived(received); entry.setReceived(received); /* * original is not detached so it will be updated on commit */ } else { /* * first instance of this alarm */ logger.trace("makePersistent alarm, key={}", entry.getKey()); entry.setReceived(1); insertManager.makePersistent(entry); logger.trace("committing"); } tx.commit(); logger.debug("finished putting alarm, key={}", entry.getKey()); } finally { AlarmJDOUtils.rollbackIfActive(tx); } } finally { /* * closing is necessary in order to avoid memory leaks */ insertManager.close(); } } @Override public long remove(Collection<LogEntry> selected) { if (selected.isEmpty()) { return 0; } PersistenceManager deleteManager = pmf.getPersistenceManager(); if (deleteManager == null) { return 0; } /** * Too many deletes in a single transaction will * cause errors, even StackOverflow exceptions. * Break up into smaller batches. */ long[] total = new long[] { 0L }; try { Iterables.partition(selected, 100).forEach((partition) -> { AlarmDAOFilter filter = AlarmJDOUtils.getIdFilter(partition); total[0] += doRemove(filter, deleteManager); }); } finally { deleteManager.close(); } return total[0]; } @Override public void run() { try { while (isRunning()) { Long currentThreshold = System.currentTimeMillis() - cleanerDeleteThresholdUnit.toMillis(cleanerDeleteThreshold); try { long count = remove(currentThreshold); logger.debug("removed {} closed alarms " + "with timestamp prior to {}", count, new Date(currentThreshold)); } catch (Exception e) { logger.error("error in alarm cleanup: {}", e.getMessage()); } cleanerSleepIntervalUnit.sleep(cleanerSleepInterval); } } catch (InterruptedException ignored) { logger.trace("cleaner thread interrupted ... exiting"); } } public void setCleanerDeleteThreshold(int cleanerDeleteThreshold) { this.cleanerDeleteThreshold = cleanerDeleteThreshold; } public void setCleanerDeleteThresholdUnit(TimeUnit timeUnit) { cleanerDeleteThresholdUnit = checkNotNull(timeUnit); } public void setCleanerEnabled(boolean cleanerEnabled) { this.cleanerEnabled = cleanerEnabled; } public void setCleanerSleepInterval(int cleanerSleepInterval) { this.cleanerSleepInterval = cleanerSleepInterval; } public void setCleanerSleepIntervalUnit(TimeUnit timeUnit) { cleanerSleepIntervalUnit = checkNotNull(timeUnit); } public void shutdown() { if (cleanerThread != null) { cleanerThread.interrupt(); } } @Override public long update(Collection<LogEntry> selected) { if (selected.isEmpty()) { return 0; } PersistenceManager updateManager = pmf.getPersistenceManager(); if (updateManager == null) { return 0; } /** * Too many object updates in a single transaction will * cause errors, even StackOverflow exceptions. * Break up into smaller batches. */ long[] total = new long[] { 0L }; try { Iterables.partition(selected, 100).forEach((partition) -> { total[0] += update(partition, updateManager); }); } finally { updateManager.close(); } return total[0]; } private long update(Collection<LogEntry> selected, PersistenceManager updateManager) { Transaction tx = updateManager.currentTransaction(); AlarmDAOFilter filter = AlarmJDOUtils.getIdFilter(selected); try { tx.begin(); Collection<LogEntry> result = AlarmJDOUtils.execute(updateManager, filter); logger.debug("got matching entries {}", result); long updated = result.size(); Map<String, LogEntry> map = new HashMap<>(); for (LogEntry e : selected) { map.put(e.getKey(), e); } for (LogEntry e : result) { e.update(map.get(e.getKey())); } /* * result is not detached so it will be updated on commit */ tx.commit(); logger.debug("successfully updated {} entries", updated); return updated; } catch (JDOException t) { logJDOException("update", filter, t); return 0; } finally { AlarmJDOUtils.rollbackIfActive(tx); } } private long doRemove(AlarmDAOFilter filter, PersistenceManager deleteManager) { Transaction tx = deleteManager.currentTransaction(); try { tx.begin(); long removed = AlarmJDOUtils.delete(deleteManager, filter); tx.commit(); logger.debug("successfully removed {} entries", removed); return removed; } catch (JDOException t) { logJDOException("remove", filter, t); return 0; } finally { AlarmJDOUtils.rollbackIfActive(tx); } } private boolean isRunning() { return cleanerThread != null && !cleanerThread.isInterrupted(); } private void logJDOException(String action, AlarmDAOFilter filter, JDOException e) { /* * JDOException extends RuntimeException, but we treat it as * a checked exception here; the SQL error should neither * be dealt with by the client nor be propagated up in this case */ if (filter == null) { logger.error("alarm data, failed to {}: {}", action, e.getMessage()); } else { logger.error("alarm data, failed to {}, {}: {}", action, filter, e.getMessage()); } } /** * Used only internally by the cleaner daemon (run()). */ private long remove(Long threshold) throws Exception { PersistenceManager deleteManager = pmf.getPersistenceManager(); try { AlarmDAOFilter filter = AlarmJDOUtils.getDeleteBeforeFilter(threshold); return doRemove(filter, deleteManager); } finally { deleteManager.close(); } } }