public long getSizeOnDisk() {
        long totalSizeBytes;
        final Path localDir = getLocalDir().toAbsolutePath();
        try (final Stream<Path> fileStream = Files.list(localDir)) {
            totalSizeBytes = fileStream
                    .mapToLong(path -> {
                        try {
                            return Files.size(path);
                        } catch (IOException e) {
                            throw new RuntimeException(e);
                        }
                    })
                    .sum();
        } catch (IOException
                 | RuntimeException e) {
            LOGGER.error("Error calculating disk usage for path {}",
                    localDir.normalize(), e);
            totalSizeBytes = -1;
        }
        return totalSizeBytes;
    }
Deletes {@link LmdbEnv} from the filesystem if it is already closed.
stroom-lmdb/src/main/java/stroom/lmdb/LmdbEnv.java