org.rocksdb.TransactionLogIterator Java Examples

void replaySince(final long transactionNumber, ReplayHandler replayHandler) {
  final ReplayHandlerWithPtrResolution replayHandlerWrapper = new ReplayHandlerWithPtrResolution(replayHandler);

  try (ReplayHandlerAdapter handler =
           new ReplayHandlerAdapter(db.getDefaultColumnFamily().getID(), replayHandlerWrapper, handleIdToNameMap);
       TransactionLogIterator iterator = db.getUpdatesSince(transactionNumber)) {
    while (iterator.isValid()) {
      iterator.status();

      final TransactionLogIterator.BatchResult result = iterator.getBatch(); // requires isValid and status check
      LOGGER.debug("Requested sequence number: {}, iterator sequence number: {}",
          transactionNumber, result.sequenceNumber());

      result.writeBatch()
          .iterate(handler);

      if (!iterator.isValid()) {
        break;
      }
      iterator.next(); // requires isValid
    }

    for (String updatedStore : handler.getUpdatedStores()) {
      final long latestTransactionNumber = metadataManager.getLatestTransactionNumber();
      metadataManager.setLatestTransactionNumber(updatedStore, latestTransactionNumber, latestTransactionNumber);
    }
  } catch (RocksDBException e) {
    throw new DatastoreException(e);
  }
}
 

Response changeFeed(Web.Request request) throws Web.ResponseException, IOException {
    String collection = request.param("collection");
    long since = Long.parseLong(request.param("since", "0"));
    long size = 10*1024*1024;
    if (request.param("size") != null) {
        size = Long.parseLong(request.param("size"));
    }

    final Index index = getIndex(request);

    if (verbose) {
        out.println(String.format("%s Received request %s. Retrieving deltas for collection <%s> since sequenceNumber %s", new Date(), request, collection, since));
    }

    try {
        /* This method must not close logReader, or you will get a segfault.
         * The response payload stream class ChangeFeedJsonStream closes it
         * when it's finished with it. */
        TransactionLogIterator logReader = index.getUpdatesSince(since);

        ChangeFeedJsonStream streamer = new ChangeFeedJsonStream(logReader, size);
        Response response = new Response(OK, "application/json", streamer);
        response.addHeader("Access-Control-Allow-Origin", "*");
        return response;
    } catch (RocksDBException e) {
        System.err.println(new Date() + " " + request.method() + " " + request.url() + " - " + e);
        if (!"Requested sequence not yet written in the db".equals(e.getMessage())) {
            e.printStackTrace();
        }
        throw new Web.ResponseException(
                new Response(Status.INTERNAL_ERROR, "text/plain", e.toString() + "\n"));
    }
}
 

@Override
public DBUpdatesWrapper getUpdatesSince(long sequenceNumber)
    throws SequenceNumberNotFoundException {

  DBUpdatesWrapper dbUpdatesWrapper = new DBUpdatesWrapper();
  try {
    TransactionLogIterator transactionLogIterator =
        db.getUpdatesSince(sequenceNumber);

    // Only the first record needs to be checked if its seq number <
    // ( 1 + passed_in_sequence_number). For example, if seqNumber passed
    // in is 100, then we can read from the WAL ONLY if the first sequence
    // number is <= 101. If it is 102, then 101 may already be flushed to
    // SST. If it 99, we can skip 99 and 100, and then read from 101.

    boolean checkValidStartingSeqNumber = true;

    while (transactionLogIterator.isValid()) {
      TransactionLogIterator.BatchResult result =
          transactionLogIterator.getBatch();
      long currSequenceNumber = result.sequenceNumber();
      if (checkValidStartingSeqNumber &&
          currSequenceNumber > 1 + sequenceNumber) {
        throw new SequenceNumberNotFoundException("Unable to read data from" +
            " RocksDB wal to get delta updates. It may have already been" +
            "flushed to SSTs.");
      }
      // If the above condition was not satisfied, then it is OK to reset
      // the flag.
      checkValidStartingSeqNumber = false;
      if (currSequenceNumber <= sequenceNumber) {
        transactionLogIterator.next();
        continue;
      }
      dbUpdatesWrapper.addWriteBatch(result.writeBatch().data(),
          result.sequenceNumber());
      transactionLogIterator.next();
    }
  } catch (RocksDBException e) {
    LOG.error("Unable to get delta updates since sequenceNumber {} ",
        sequenceNumber, e);
  }
  return dbUpdatesWrapper;
}
 

public TransactionLogIterator getUpdatesSince(long sequenceNumber) throws RocksDBException {
    TransactionLogIterator logReader = db.getUpdatesSince(sequenceNumber);
    return logReader;
}
 

ChangeFeedJsonStream(TransactionLogIterator logReader, long batchSize) {
    this.logReader = logReader;
    this.batchSize = batchSize;
}