Exemplo n.º 1
0
Try<Nothing> LevelDBStorage::persist(const Metadata& metadata)
{
  Stopwatch stopwatch;
  stopwatch.start();

  leveldb::WriteOptions options;
  options.sync = true;

  Record record;
  record.set_type(Record::METADATA);
  record.mutable_metadata()->CopyFrom(metadata);

  string value;

  if (!record.SerializeToString(&value)) {
    return Error("Failed to serialize record");
  }

  leveldb::Status status = db->Put(options, encode(0, false), value);

  if (!status.ok()) {
    return Error(status.ToString());
  }

  LOG(INFO) << "Persisting metadata (" << value.size()
            << " bytes) to leveldb took " << stopwatch.elapsed();

  return Nothing();
}
Exemplo n.º 2
0
Try<Nothing> LevelDBStorage::persist(const Action& action)
{
  Stopwatch stopwatch;
  stopwatch.start();

  Record record;
  record.set_type(Record::ACTION);
  record.mutable_action()->MergeFrom(action);

  string value;

  if (!record.SerializeToString(&value)) {
    return Error("Failed to serialize record");
  }

  leveldb::WriteOptions options;
  options.sync = true;

  leveldb::Status status = db->Put(options, encode(action.position()), value);

  if (!status.ok()) {
    return Error(status.ToString());
  }

  // Updated the first position. Notice that we use 'min' here instead
  // of checking 'isNone()' because it's likely that log entries are
  // written out of order during catch-up (e.g. if a random bulk
  // catch-up policy is used).
  first = min(first, action.position());

  LOG(INFO) << "Persisting action (" << value.size()
            << " bytes) to leveldb took " << stopwatch.elapsed();

  // Delete positions if a truncate action has been *learned*. Note
  // that we do this in a best-effort fashion (i.e., we ignore any
  // failures to the database since we can always try again).
  if (action.has_type() && action.type() == Action::TRUNCATE &&
      action.has_learned() && action.learned()) {
    CHECK(action.has_truncate());

    stopwatch.start(); // Restart the stopwatch.

    // To actually perform the truncation in leveldb we need to remove
    // all the keys that represent positions no longer in the log. We
    // do this by attempting to delete all keys that represent the
    // first position we know is still in leveldb up to (but
    // excluding) the truncate position. Note that this works because
    // the semantics of WriteBatch are such that even if the position
    // doesn't exist (which is possible because this replica has some
    // holes), we can attempt to delete the key that represents it and
    // it will just ignore that key. This is *much* cheaper than
    // actually iterating through the entire database instead (which
    // was, for posterity, the original implementation). In addition,
    // caching the "first" position we know is in the database is
    // cheaper than using an iterator to determine the first position
    // (which was, for posterity, the second implementation).

    leveldb::WriteBatch batch;

    CHECK_SOME(first);

    // Add positions up to (but excluding) the truncate position to
    // the batch starting at the first position still in leveldb. It's
    // likely that the first position is greater than the truncate
    // position (e.g., during catch-up). In that case, we do nothing
    // because there is nothing we can truncate.
    // TODO(jieyu): We might miss a truncation if we do random (i.e.,
    // out of order) bulk catch-up and the truncate operation is
    // caught up first.
    uint64_t index = 0;
    while ((first.get() + index) < action.truncate().to()) {
      batch.Delete(encode(first.get() + index));
      index++;
    }

    // If we added any positions, attempt to delete them!
    if (index > 0) {
      // We do this write asynchronously (e.g., using default options).
      leveldb::Status status = db->Write(leveldb::WriteOptions(), &batch);

      if (!status.ok()) {
        LOG(WARNING) << "Ignoring leveldb batch delete failure: "
                     << status.ToString();
      } else {
        // Save the new first position!
        CHECK_LT(first.get(), action.truncate().to());
        first = action.truncate().to();

        LOG(INFO) << "Deleting ~" << index
                  << " keys from leveldb took " << stopwatch.elapsed();
      }
    }
  }

  return Nothing();
}