Java Code Examples for org.apache.nifi.provenance.serialization.RecordReaders#newRecordReader()

private Long getFirstEntryTime(final File provenanceLogFile) {
    if (provenanceLogFile == null) {
        return null;
    }

    try (final RecordReader reader = RecordReaders.newRecordReader(provenanceLogFile, null, Integer.MAX_VALUE)) {
        final StandardProvenanceEventRecord firstRecord = reader.nextRecord();
        if (firstRecord == null) {
            return provenanceLogFile.lastModified();
        }
        return firstRecord.getEventTime();
    } catch (final FileNotFoundException | EOFException fnf) {
        return null; // file no longer exists or there's no record in this file
    } catch (final IOException ioe) {
        logger.warn("Failed to read first entry in file {} due to {}", provenanceLogFile, ioe.toString());
        logger.warn("", ioe);
        return null;
    }
}
 

private long determineFirstEventTimestamp() {
    // Get the timestamp of the first event in the first Provenance Event Log File and the ID of the last event
    // in the event file.
    final List<File> logFiles = getSortedLogFiles();
    if (logFiles.isEmpty()) {
        return 0L;
    }

    for (final File logFile : logFiles) {
        try (final RecordReader reader = RecordReaders.newRecordReader(logFile, null, Integer.MAX_VALUE)) {
            final StandardProvenanceEventRecord event = reader.nextRecord();
            if (event != null) {
                return event.getEventTime();
            }
        } catch (final IOException ioe) {
            logger.warn("Failed to obtain timestamp of first event from Provenance Event Log File {}", logFile);
        }
    }

    return 0L;
}
 

public static void main(final String[] args) throws IOException {
    if (args.length != 1) {
        printUsage();
        return;
    }

    final File file = new File(args[0]);
    if (!file.exists()) {
        System.out.println("Cannot find file " + file.getAbsolutePath());
        return;
    }

    try (final RecordReader reader = RecordReaders.newRecordReader(file, Collections.emptyList(), 65535)) {
        StandardProvenanceEventRecord event;
        int index = 0;
        while ((event = reader.nextRecord()) != null) {
            final long byteOffset = reader.getBytesConsumed();
            final String string = stringify(event, index++, byteOffset);
            System.out.println(string);
        }
    }
}
 

private long checkJournalRecords(final File storageDir, final Boolean exact) throws IOException {
    File[] storagefiles = storageDir.listFiles();
    long counter = 0;
    assertNotNull(storagefiles);
    for (final File file : storagefiles) {
        if (file.isFile()) {
            try (RecordReader reader = RecordReaders.newRecordReader(file, null, 2048)) {
                ProvenanceEventRecord r;
                ProvenanceEventRecord last = null;
                while ((r = reader.nextRecord()) != null) {
                    if (exact) {
                        assertTrue(counter++ == r.getEventId());
                    } else {
                        assertTrue(counter++ <= r.getEventId());
                    }
                }
            }
        }
    }
    return counter;
}
 

@Test
public void testFileNotFound() throws IOException {
    final File file1 = new File("1.prov");

    // Filter out the first file.
    final List<File> files = new ArrayList<>();
    files.add(file1);

    List<Long> eventIds = new ArrayList<>();
    eventIds.add(1L);
    eventIds.add(5L);

    final RecordReaderFactory readerFactory = (file, logs, maxChars) -> {
        return RecordReaders.newRecordReader(file, logs, maxChars);
    };

    final SelectiveRecordReaderEventIterator itr = new SelectiveRecordReaderEventIterator(files, readerFactory, eventIds, 65536);
    final Optional<ProvenanceEventRecord> firstRecordOption = itr.nextEvent();
    assertFalse(firstRecordOption.isPresent());
}
 

private long checkJournalRecords(final File storageDir, final Boolean exact) throws IOException {
    File[] storagefiles = storageDir.listFiles();
    long counter = 0;
    assertNotNull(storagefiles);
    for (final File file : storagefiles) {
        if (file.isFile()) {
            try (RecordReader reader = RecordReaders.newRecordReader(file, null, 2048)) {
                ProvenanceEventRecord r;
                ProvenanceEventRecord last = null;
                while ((r = reader.nextRecord()) != null) {
                    if (exact) {
                        assertTrue(counter++ == r.getEventId());
                    } else {
                        assertTrue(counter++ <= r.getEventId());
                    }
                }
            }
        }
    }
    return counter;
}
 

private long checkJournalRecords(final File storageDir, final Boolean exact) throws IOException {
    File[] storagefiles = storageDir.listFiles();
    long counter = 0;
    assertNotNull(storagefiles);
    for (final File file : storagefiles) {
        if (file.isFile()) {
            try (RecordReader reader = RecordReaders.newRecordReader(file, null, 2048)) {
                ProvenanceEventRecord r;
                ProvenanceEventRecord last = null;
                while ((r = reader.nextRecord()) != null) {
                    if (exact) {
                        assertTrue(counter++ == r.getEventId());
                    } else {
                        assertTrue(counter++ <= r.getEventId());
                    }
                }
            }
        }
    }
    return counter;
}
 

public static void main(final String[] args) throws IOException {
    if (args.length != 1) {
        printUsage();
        return;
    }

    final File file = new File(args[0]);
    if (!file.exists()) {
        System.out.println("Cannot find file " + file.getAbsolutePath());
        return;
    }

    try (final RecordReader reader = RecordReaders.newRecordReader(file, Collections.emptyList(), 65535)) {
        StandardProvenanceEventRecord event;
        int index = 0;
        while ((event = reader.nextRecord()) != null) {
            final long byteOffset = reader.getBytesConsumed();
            final String string = stringify(event, index++, byteOffset);
            System.out.println(string);
        }
    }
}
 

@Override
public File execute(final File expiredFile) throws IOException {
    try (final RecordReader reader = RecordReaders.newRecordReader(expiredFile, null, Integer.MAX_VALUE)) {
        final long maxEventId = reader.getMaxEventId();
        indexConfig.setMinIdIndexed(maxEventId);

        logger.info("Updated Minimum Event ID for Provenance Event Repository - Minimum Event ID now {}", maxEventId);
    } catch (final IOException ioe) {
        logger.warn("Failed to obtain max ID present in journal file {}", expiredFile.getAbsolutePath());
    }

    return expiredFile;
}
 

@Override
public File execute(final File expiredFile) throws IOException {
    try (final RecordReader reader = RecordReaders.newRecordReader(expiredFile, null, Integer.MAX_VALUE)) {
        final long maxEventId = reader.getMaxEventId();
        indexConfig.setMinIdIndexed(maxEventId);

        logger.info("Updated Minimum Event ID for Provenance Event Repository - Minimum Event ID now {}", maxEventId);
    } catch (final IOException ioe) {
        logger.warn("Failed to obtain max ID present in journal file {}", expiredFile.getAbsolutePath());
    }

    return expiredFile;
}
 

private void purgeExpiredIndexes() throws IOException {
    // Now that we have potentially removed expired Provenance Event Log Files, we can look at
    // whether or not we can delete any of the indexes. An index can be deleted if all of the
    // data that is associated with that index has already been deleted. In order to test this,
    // we will get the timestamp of the earliest event and then compare that to the latest timestamp
    // that would be indexed by the earliest index. If the event occurred after the timestamp of
    // the latest index, then we can just delete the entire index all together.

    // find all of the index directories
    final List<File> indexDirs = getAllIndexDirectories();
    if (indexDirs.size() < 2) {
        this.firstEventTimestamp = determineFirstEventTimestamp();
        return;
    }

    // Indexes are named "index-XXX" where the XXX is the timestamp of the earliest event that
    // could be in the index. Once we have finished with one index, we move on to another index,
    // but we don't move on until we are finished with the previous index.
    // Therefore, an efficient way to determine the latest timestamp of one index is to look at the
    // timestamp of the next index (these could potentially overlap for one millisecond). This is
    // efficient because we can determine the earliest timestamp of an index simply by looking at
    // the name of the Index's directory.
    final long latestTimestampOfFirstIndex = getIndexTimestamp(indexDirs.get(1));

    // Get the timestamp of the first event in the first Provenance Event Log File and the ID of the last event
    // in the event file.
    final List<File> logFiles = getSortedLogFiles();
    if (logFiles.isEmpty()) {
        this.firstEventTimestamp = System.currentTimeMillis();
        return;
    }

    final File firstLogFile = logFiles.get(0);
    long earliestEventTime = System.currentTimeMillis();
    long maxEventId = -1L;
    try (final RecordReader reader = RecordReaders.newRecordReader(firstLogFile, null, Integer.MAX_VALUE)) {
        final StandardProvenanceEventRecord event = reader.nextRecord();
        earliestEventTime = event.getEventTime();
        maxEventId = reader.getMaxEventId();
    } catch (final IOException ioe) {
        logger.warn("Unable to determine the maximum ID for Provenance Event Log File {}; values reported for the number of "
                + "events in the Provenance Repository may be inaccurate.", firstLogFile);
    }

    // check if we can delete the index safely.
    if (latestTimestampOfFirstIndex <= earliestEventTime) {
        // we can safely delete the first index because the latest event in the index is an event
        // that has already been expired from the repository.
        final File indexingDirectory = indexDirs.get(0);
        getIndexManager().removeIndex(indexingDirectory);
        indexConfig.removeIndexDirectory(indexingDirectory);
        deleteDirectory(indexingDirectory);

        if (maxEventId > -1L) {
            indexConfig.setMinIdIndexed(maxEventId + 1L);
        }
    }

    this.firstEventTimestamp = earliestEventTime;
}
 

@Override
public List<ProvenanceEventRecord> getEvents(final long firstRecordId, final int maxRecords, final NiFiUser user) throws IOException {
    final List<ProvenanceEventRecord> records = new ArrayList<>(maxRecords);

    final List<Path> paths = getPathsForId(firstRecordId);
    if (paths == null || paths.isEmpty()) {
        return records;
    }

    for (final Path path : paths) {
        try (RecordReader reader = RecordReaders.newRecordReader(path.toFile(), getAllLogFiles(), maxAttributeChars)) {
            // if this is the first record, try to find out the block index and jump directly to
            // the block index. This avoids having to read through a lot of data that we don't care about
            // just to get to the first record that we want.
            if (records.isEmpty()) {
                final TocReader tocReader = reader.getTocReader();
                if (tocReader != null) {
                    final Integer blockIndex = tocReader.getBlockIndexForEventId(firstRecordId);
                    if (blockIndex != null) {
                        reader.skipToBlock(blockIndex);
                    }
                }
            }

            StandardProvenanceEventRecord record;
            while (records.size() < maxRecords && (record = reader.nextRecord()) != null) {
                if (record.getEventId() >= firstRecordId && isAuthorized(record, user)) {
                    records.add(record);
                }
            }
        } catch (final EOFException | FileNotFoundException fnfe) {
            // assume file aged off (or there's no data in file, in case of EOFException, which indicates that data was cached
            // in operating system and entire O/S crashed and always.sync was not turned on.)
        } catch (final IOException ioe) {
            logger.error("Failed to read Provenance Event File {} due to {}", path.toFile(), ioe.toString());
            logger.error("", ioe);
            eventReporter.reportEvent(Severity.ERROR, EVENT_CATEGORY, "Failed to read Provenance Event File " + path.toFile() + " due to " + ioe.toString());
        }

        if (records.size() >= maxRecords) {
            break;
        }
    }

    if (logger.isDebugEnabled()) {
        logger.debug("Retrieving up to {} records starting at Event ID {}; returning {} events", maxRecords, firstRecordId, records.size());
    }

    return records;
}
 

@Test
public void testMergeJournals() throws IOException, InterruptedException {
    assumeFalse(isWindowsEnvironment());
    final RepositoryConfiguration config = createConfiguration();
    config.setMaxEventFileLife(3, TimeUnit.SECONDS);
    repo = new PersistentProvenanceRepository(config, DEFAULT_ROLLOVER_MILLIS);
    repo.initialize(getEventReporter(), null, null, IdentifierLookup.EMPTY);

    final Map<String, String> attributes = new HashMap<>();

    final ProvenanceEventBuilder builder = new StandardProvenanceEventRecord.Builder();
    builder.setEventTime(System.currentTimeMillis());
    builder.setEventType(ProvenanceEventType.RECEIVE);
    builder.setTransitUri("nifi://unit-test");
    attributes.put("uuid", "12345678-0000-0000-0000-012345678912");
    builder.fromFlowFile(createFlowFile(3L, 3000L, attributes));
    builder.setComponentId("1234");
    builder.setComponentType("dummy processor");

    final ProvenanceEventRecord record = builder.build();

    final ExecutorService exec = Executors.newFixedThreadPool(10);
    for (int i = 0; i < 10000; i++) {
        exec.submit(new Runnable() {
            @Override
            public void run() {
                repo.registerEvent(record);
            }
        });
    }

    repo.waitForRollover();

    final File storageDir = config.getStorageDirectories().values().iterator().next();
    long counter = 0;
    for (final File file : storageDir.listFiles()) {
        if (file.isFile()) {

            try (RecordReader reader = RecordReaders.newRecordReader(file, null, 2048)) {
                ProvenanceEventRecord r = null;

                while ((r = reader.nextRecord()) != null) {
                    assertEquals(counter++, r.getEventId());
                }
            }
        }
    }

    assertEquals(10000, counter);
}
 

@Override
public File execute(final File expiredFile) throws IOException {
    // count the number of records and determine the max event id that we are deleting.
    final long numDeleted = 0;
    long maxEventId = -1L;
    try (final RecordReader reader = RecordReaders.newRecordReader(expiredFile, repository.getAllLogFiles(), Integer.MAX_VALUE)) {
        maxEventId = reader.getMaxEventId();
    } catch (final IOException ioe) {
        logger.warn("Failed to obtain max ID present in journal file {}", expiredFile.getAbsolutePath());
    }

    // remove the records from the index
    final List<File> indexDirs = indexConfiguration.getIndexDirectories(expiredFile);
    for (final File indexingDirectory : indexDirs) {
        final Term term = new Term(FieldNames.STORAGE_FILENAME, LuceneUtil.substringBefore(expiredFile.getName(), "."));

        boolean deleteDir = false;
        final EventIndexWriter writer = indexManager.borrowIndexWriter(indexingDirectory);
        try {
            final IndexWriter indexWriter = writer.getIndexWriter();
            indexWriter.deleteDocuments(term);
            indexWriter.commit();
            final int docsLeft = indexWriter.getDocStats().numDocs;
            deleteDir = docsLeft <= 0;
            logger.debug("After expiring {}, there are {} docs left for index {}", expiredFile, docsLeft, indexingDirectory);
        } finally {
            indexManager.returnIndexWriter(writer);
        }

        // we've confirmed that all documents have been removed. Delete the index directory.
        if (deleteDir) {
            indexManager.removeIndex(indexingDirectory);
            indexConfiguration.removeIndexDirectory(indexingDirectory);

            deleteDirectory(indexingDirectory);
            logger.info("Removed empty index directory {}", indexingDirectory);
        }
    }

    // Update the minimum index to 1 more than the max Event ID in this file.
    if (maxEventId > -1L) {
        indexConfiguration.setMinIdIndexed(maxEventId + 1L);
    }

    logger.info("Deleted Indices for Expired Provenance File {} from {} index files; {} documents removed", expiredFile, indexDirs.size(), numDeleted);
    return expiredFile;
}
 

private void purgeExpiredIndexes() throws IOException {
    // Now that we have potentially removed expired Provenance Event Log Files, we can look at
    // whether or not we can delete any of the indexes. An index can be deleted if all of the
    // data that is associated with that index has already been deleted. In order to test this,
    // we will get the timestamp of the earliest event and then compare that to the latest timestamp
    // that would be indexed by the earliest index. If the event occurred after the timestamp of
    // the latest index, then we can just delete the entire index all together.

    // find all of the index directories
    final List<File> indexDirs = getAllIndexDirectories();
    if (indexDirs.size() < 2) {
        this.firstEventTimestamp = determineFirstEventTimestamp();
        return;
    }

    // Indexes are named "index-XXX" where the XXX is the timestamp of the earliest event that
    // could be in the index. Once we have finished with one index, we move on to another index,
    // but we don't move on until we are finished with the previous index.
    // Therefore, an efficient way to determine the latest timestamp of one index is to look at the
    // timestamp of the next index (these could potentially overlap for one millisecond). This is
    // efficient because we can determine the earliest timestamp of an index simply by looking at
    // the name of the Index's directory.
    final long latestTimestampOfFirstIndex = getIndexTimestamp(indexDirs.get(1));

    // Get the timestamp of the first event in the first Provenance Event Log File and the ID of the last event
    // in the event file.
    final List<File> logFiles = getSortedLogFiles();
    if (logFiles.isEmpty()) {
        this.firstEventTimestamp = System.currentTimeMillis();
        return;
    }

    final File firstLogFile = logFiles.get(0);
    long earliestEventTime = System.currentTimeMillis();
    long maxEventId = -1L;
    try (final RecordReader reader = RecordReaders.newRecordReader(firstLogFile, null, Integer.MAX_VALUE)) {
        final StandardProvenanceEventRecord event = reader.nextRecord();
        earliestEventTime = event.getEventTime();
        maxEventId = reader.getMaxEventId();
    } catch (final IOException ioe) {
        logger.warn("Unable to determine the maximum ID for Provenance Event Log File {}; values reported for the number of "
                + "events in the Provenance Repository may be inaccurate.", firstLogFile);
    }

    // check if we can delete the index safely.
    if (latestTimestampOfFirstIndex <= earliestEventTime) {
        // we can safely delete the first index because the latest event in the index is an event
        // that has already been expired from the repository.
        final File indexingDirectory = indexDirs.get(0);
        getIndexManager().removeIndex(indexingDirectory);
        indexConfig.removeIndexDirectory(indexingDirectory);
        deleteDirectory(indexingDirectory);

        if (maxEventId > -1L) {
            indexConfig.setMinIdIndexed(maxEventId + 1L);
        }
    }

    this.firstEventTimestamp = earliestEventTime;
}
 

public Set<ProvenanceEventRecord> read(final List<Document> docs, final EventAuthorizer authorizer, final Collection<Path> allProvenanceLogFiles,
        final AtomicInteger retrievalCount, final int maxResults, final int maxAttributeChars) throws IOException {

    if (retrievalCount.get() >= maxResults) {
        return Collections.emptySet();
    }

    final long start = System.nanoTime();
    final Set<ProvenanceEventRecord> matchingRecords = new LinkedHashSet<>();
    final Map<String, List<Document>> byStorageNameDocGroups = LuceneUtil.groupDocsByStorageFileName(docs);

    int eventsReadThisFile = 0;
    int logFileCount = 0;

    for (String storageFileName : byStorageNameDocGroups.keySet()) {
        final File provenanceEventFile = LuceneUtil.getProvenanceLogFile(storageFileName, allProvenanceLogFiles);
        if (provenanceEventFile == null) {
            logger.warn("Could not find Provenance Log File with "
                + "basename {} in the Provenance Repository; assuming "
                + "file has expired and continuing without it", storageFileName);
            continue;
        }

        try (final RecordReader reader = RecordReaders.newRecordReader(provenanceEventFile, allProvenanceLogFiles, maxAttributeChars)) {
            final Iterator<Document> docIter = byStorageNameDocGroups.get(storageFileName).iterator();
            while (docIter.hasNext() && retrievalCount.getAndIncrement() < maxResults) {
                final ProvenanceEventRecord event = getRecord(docIter.next(), reader);
                if (event != null && authorizer.isAuthorized(event)) {
                    matchingRecords.add(event);
                    eventsReadThisFile++;
                }
            }
        } catch (final Exception e) {
            logger.warn("Failed to read Provenance Events. The event file '"
                + provenanceEventFile.getAbsolutePath() + "' may be missing or corrupt.", e);
        }
    }

    logger.debug("Read {} records from previous file", eventsReadThisFile);
    final long millis = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
    logger.debug("Took {} ms to read {} events from {} prov log files", millis, matchingRecords.size(),
            logFileCount);

    return matchingRecords;
}
 

public Set<ProvenanceEventRecord> read(final List<Document> docs, final EventAuthorizer authorizer, final Collection<Path> allProvenanceLogFiles,
        final AtomicInteger retrievalCount, final int maxResults, final int maxAttributeChars) throws IOException {

    if (retrievalCount.get() >= maxResults) {
        return Collections.emptySet();
    }

    final long start = System.nanoTime();
    final Set<ProvenanceEventRecord> matchingRecords = new LinkedHashSet<>();
    final Map<String, List<Document>> byStorageNameDocGroups = LuceneUtil.groupDocsByStorageFileName(docs);

    int eventsReadThisFile = 0;
    int logFileCount = 0;

    for (String storageFileName : byStorageNameDocGroups.keySet()) {
        final File provenanceEventFile = LuceneUtil.getProvenanceLogFile(storageFileName, allProvenanceLogFiles);
        if (provenanceEventFile == null) {
            logger.warn("Could not find Provenance Log File with "
                + "basename {} in the Provenance Repository; assuming "
                + "file has expired and continuing without it", storageFileName);
            continue;
        }

        try (final RecordReader reader = RecordReaders.newRecordReader(provenanceEventFile, allProvenanceLogFiles, maxAttributeChars)) {
            final Iterator<Document> docIter = byStorageNameDocGroups.get(storageFileName).iterator();
            while (docIter.hasNext() && retrievalCount.getAndIncrement() < maxResults) {
                final ProvenanceEventRecord event = getRecord(docIter.next(), reader);
                if (event != null && authorizer.isAuthorized(event)) {
                    matchingRecords.add(event);
                    eventsReadThisFile++;
                }
            }
        } catch (final Exception e) {
            logger.warn("Failed to read Provenance Events. The event file '"
                + provenanceEventFile.getAbsolutePath() + "' may be missing or corrupt.", e);
        }
    }

    logger.debug("Read {} records from previous file", eventsReadThisFile);
    final long millis = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
    logger.debug("Took {} ms to read {} events from {} prov log files", millis, matchingRecords.size(),
            logFileCount);

    return matchingRecords;
}
 

@Override
public File execute(final File expiredFile) throws IOException {
    // count the number of records and determine the max event id that we are deleting.
    final long numDeleted = 0;
    long maxEventId = -1L;
    try (final RecordReader reader = RecordReaders.newRecordReader(expiredFile, repository.getAllLogFiles(), Integer.MAX_VALUE)) {
        maxEventId = reader.getMaxEventId();
    } catch (final IOException ioe) {
        logger.warn("Failed to obtain max ID present in journal file {}", expiredFile.getAbsolutePath());
    }

    // remove the records from the index
    final List<File> indexDirs = indexConfiguration.getIndexDirectories(expiredFile);
    for (final File indexingDirectory : indexDirs) {
        final Term term = new Term(FieldNames.STORAGE_FILENAME, LuceneUtil.substringBefore(expiredFile.getName(), "."));

        boolean deleteDir = false;
        final EventIndexWriter writer = indexManager.borrowIndexWriter(indexingDirectory);
        try {
            final IndexWriter indexWriter = writer.getIndexWriter();
            indexWriter.deleteDocuments(term);
            indexWriter.commit();
            final int docsLeft = indexWriter.numDocs();
            deleteDir = docsLeft <= 0;
            logger.debug("After expiring {}, there are {} docs left for index {}", expiredFile, docsLeft, indexingDirectory);
        } finally {
            indexManager.returnIndexWriter(writer);
        }

        // we've confirmed that all documents have been removed. Delete the index directory.
        if (deleteDir) {
            indexManager.removeIndex(indexingDirectory);
            indexConfiguration.removeIndexDirectory(indexingDirectory);

            deleteDirectory(indexingDirectory);
            logger.info("Removed empty index directory {}", indexingDirectory);
        }
    }

    // Update the minimum index to 1 more than the max Event ID in this file.
    if (maxEventId > -1L) {
        indexConfiguration.setMinIdIndexed(maxEventId + 1L);
    }

    logger.info("Deleted Indices for Expired Provenance File {} from {} index files; {} documents removed", expiredFile, indexDirs.size(), numDeleted);
    return expiredFile;
}
 

private void purgeExpiredIndexes() throws IOException {
    // Now that we have potentially removed expired Provenance Event Log Files, we can look at
    // whether or not we can delete any of the indexes. An index can be deleted if all of the
    // data that is associated with that index has already been deleted. In order to test this,
    // we will get the timestamp of the earliest event and then compare that to the latest timestamp
    // that would be indexed by the earliest index. If the event occurred after the timestamp of
    // the latest index, then we can just delete the entire index all together.

    // find all of the index directories
    final List<File> indexDirs = getAllIndexDirectories();
    if (indexDirs.size() < 2) {
        this.firstEventTimestamp = determineFirstEventTimestamp();
        return;
    }

    // Indexes are named "index-XXX" where the XXX is the timestamp of the earliest event that
    // could be in the index. Once we have finished with one index, we move on to another index,
    // but we don't move on until we are finished with the previous index.
    // Therefore, an efficient way to determine the latest timestamp of one index is to look at the
    // timestamp of the next index (these could potentially overlap for one millisecond). This is
    // efficient because we can determine the earliest timestamp of an index simply by looking at
    // the name of the Index's directory.
    final long latestTimestampOfFirstIndex = getIndexTimestamp(indexDirs.get(1));

    // Get the timestamp of the first event in the first Provenance Event Log File and the ID of the last event
    // in the event file.
    final List<File> logFiles = getSortedLogFiles();
    if (logFiles.isEmpty()) {
        this.firstEventTimestamp = System.currentTimeMillis();
        return;
    }

    final File firstLogFile = logFiles.get(0);
    long earliestEventTime = System.currentTimeMillis();
    long maxEventId = -1L;
    try (final RecordReader reader = RecordReaders.newRecordReader(firstLogFile, null, Integer.MAX_VALUE)) {
        final StandardProvenanceEventRecord event = reader.nextRecord();
        earliestEventTime = event.getEventTime();
        maxEventId = reader.getMaxEventId();
    } catch (final IOException ioe) {
        logger.warn("Unable to determine the maximum ID for Provenance Event Log File {}; values reported for the number of "
                + "events in the Provenance Repository may be inaccurate.", firstLogFile);
    }

    // check if we can delete the index safely.
    if (latestTimestampOfFirstIndex <= earliestEventTime) {
        // we can safely delete the first index because the latest event in the index is an event
        // that has already been expired from the repository.
        final File indexingDirectory = indexDirs.get(0);
        getIndexManager().removeIndex(indexingDirectory);
        indexConfig.removeIndexDirectory(indexingDirectory);
        deleteDirectory(indexingDirectory);

        if (maxEventId > -1L) {
            indexConfig.setMinIdIndexed(maxEventId + 1L);
        }
    }

    this.firstEventTimestamp = earliestEventTime;
}
 

@Override
public List<ProvenanceEventRecord> getEvents(final long firstRecordId, final int maxRecords, final NiFiUser user) throws IOException {
    final List<ProvenanceEventRecord> records = new ArrayList<>(maxRecords);

    final List<Path> paths = getPathsForId(firstRecordId);
    if (paths == null || paths.isEmpty()) {
        return records;
    }

    for (final Path path : paths) {
        try (RecordReader reader = RecordReaders.newRecordReader(path.toFile(), getAllLogFiles(), maxAttributeChars)) {
            // if this is the first record, try to find out the block index and jump directly to
            // the block index. This avoids having to read through a lot of data that we don't care about
            // just to get to the first record that we want.
            if (records.isEmpty()) {
                final TocReader tocReader = reader.getTocReader();
                if (tocReader != null) {
                    final Integer blockIndex = tocReader.getBlockIndexForEventId(firstRecordId);
                    if (blockIndex != null) {
                        reader.skipToBlock(blockIndex);
                    }
                }
            }

            StandardProvenanceEventRecord record;
            while (records.size() < maxRecords && (record = reader.nextRecord()) != null) {
                if (record.getEventId() >= firstRecordId && isAuthorized(record, user)) {
                    records.add(record);
                }
            }
        } catch (final EOFException | FileNotFoundException fnfe) {
            // assume file aged off (or there's no data in file, in case of EOFException, which indicates that data was cached
            // in operating system and entire O/S crashed and always.sync was not turned on.)
        } catch (final IOException ioe) {
            logger.error("Failed to read Provenance Event File {} due to {}", path.toFile(), ioe.toString());
            logger.error("", ioe);
            eventReporter.reportEvent(Severity.ERROR, EVENT_CATEGORY, "Failed to read Provenance Event File " + path.toFile() + " due to " + ioe.toString());
        }

        if (records.size() >= maxRecords) {
            break;
        }
    }

    if (logger.isDebugEnabled()) {
        logger.debug("Retrieving up to {} records starting at Event ID {}; returning {} events", maxRecords, firstRecordId, records.size());
    }

    return records;
}