You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/diem/consensus/src/consensusdb
    
    the code of the file until where you have to start completion: // Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

#[cfg(test)]
mod consensusdb_test;
mod schema;

use crate::{
    consensusdb::schema::{
        block::BlockSchema,
        quorum_certificate::QCSchema,
        single_entry::{SingleEntryKey, SingleEntrySchema},
    },
    error::DbError,
};
use anyhow::Result;
use consensus_types::{block::Block, quorum_cert::QuorumCert};
use diem_crypto::HashValue;
use diem_logger::prelude::*;
use schema::{BLOCK_CF_NAME, QC_CF_NAME, SINGLE_ENTRY_CF_NAME};
use schemadb::{Options, ReadOptions, SchemaBatch, DB, DEFAULT_CF_NAME};
use std::{collections::HashMap, iter::Iterator, path::Path, time::Instant};

pub struct C
    
    pub fn new<P: AsRef<Path> + Clone>(db_root_path: P) -> Self {
        let column_families = vec![
            /* UNUSED CF = */ DEFAULT_CF_NAME,
            BLOCK_CF_NAME,
            QC_CF_NAME,
            SINGLE_ENTRY_CF_NAME,
        ];

        let path = db_root_path.as_ref().join("consensusdb");
        let instant = Instant::now();
        let mut opts = Options::default();
        opts.create_if_missing(true);
        opts.create_missing_column_families(true);
        let db = DB::open(path.clone(), "consensus", column_families, &opts)
            .expect("ConsensusDB open failed; unable to continue");

        info!(
            "Opened ConsensusDB at {:?} in {} ms",
            path,
            instant.elapsed().as_millis()
        );

        Self { db }
    }