fn get_account_data_from_address(
        client: &GRPCClient,
        address: AccountAddress,
        key_pair: Option<KeyPair>,
    ) -> Result<AccountData> 

pub(crate) fn get_account_blob(
        &self,
        address: AccountAddress,
    ) -> Result<(Option<AccountStateBlob>, Version)>{
        let req_item = RequestItem::GetAccountState { address };

        let mut response = self.get_with_proof_sync(vec![req_item])?;
        ...//处理返回结果

    }

 pub(crate) fn get_with_proof_sync(
        &self,
        requested_items: Vec<RequestItem>,
    ) -> Result<UpdateToLatestLedgerResponse> 

 let mut resp: Result<UpdateToLatestLedgerResponse> =
            self.get_with_proof_async(requested_items.clone())?.wait();

 fn get_with_proof_async(
        &self,
        requested_items: Vec<RequestItem>,
    ) -> Result<impl Future<Item = UpdateToLatestLedgerResponse, Error = failure::Error>> 

impl Storage for StorageService {
    fn update_to_latest_ledger(
        &mut self,
        ctx: grpcio::RpcContext<'_>,
        req: UpdateToLatestLedgerRequest,
        sink: grpcio::UnarySink<UpdateToLatestLedgerResponse>,
    ) {
        debug!("[GRPC] Storage::update_to_latest_ledger");
        let _timer = SVC_COUNTERS.req(&ctx);
        let resp = self.update_to_latest_ledger_inner(req);
        provide_grpc_response(resp, ctx, sink);
    }

/// This holds a handle to the underlying DB responsible for physical storage and provides APIs for
/// access to the core Libra data structures.
pub struct LibraDB {
    db: Arc<DB>,
    ledger_store: LedgerStore,
    transaction_store: TransactionStore,
    state_store: StateStore,
    event_store: EventStore,
}

impl LibraDB {
    /// This creates an empty LibraDB instance on disk or opens one if it already exists.
    pub fn new<P: AsRef<Path> + Clone>(db_root_path: P) -> Self 

      /// Persist transactions. Called by the executor module when either syncing nodes or committing
    /// blocks during normal operation.
    ///
    /// When `ledger_info_with_sigs` is provided, verify that the transaction accumulator root hash
    /// it carries is generated after the `txns_to_commit` are applied.
    pub fn save_transactions(
        &self,
        txns_to_commit: &[TransactionToCommit],
        first_version: Version,
        ledger_info_with_sigs: &Option<LedgerInfoWithSignatures>,
    ) -> Result<()>  ;
 
     /// This backs the `UpdateToLatestLedger` public read API which returns the latest
    /// [`LedgerInfoWithSignatures`] together with items requested and proofs relative to the same
    /// ledger info.
    pub fn update_to_latest_ledger(
        &self,
        _client_known_version: u64,
        request_items: Vec<RequestItem>,
    ) -> Result<(
        Vec<ResponseItem>,
        LedgerInfoWithSignatures,
        Vec<ValidatorChangeEventWithProof>,
    )> 

     /// Gets an account state by account address, out of the ledger state indicated by the state
    /// Merkle tree root hash.
    ///
    /// This is used by the executor module internally.
    pub fn get_account_state_with_proof_by_state_root(
        &self,
        address: AccountAddress,
        state_root: HashValue,
    ) -> Result<(Option<AccountStateBlob>, SparseMerkleProof)>;

       /// Gets information needed from storage during the startup of the executor module.
    ///
    /// This is used by the executor module internally.
    pub fn get_executor_startup_info(&self) -> Result<Option<ExecutorStartupInfo>>;

       /// Gets a batch of transactions for the purpose of synchronizing state to another node.
    ///
    /// This is used by the State Synchronizer module internally.
    pub fn get_transactions(
        &self,
        start_version: Version,
        limit: u64,
        ledger_version: Version,
        fetch_events: bool,
    ) -> Result<TransactionListWithProof>;

    /// This backs the `UpdateToLatestLedger` public read API which returns the latest
    /// [`LedgerInfoWithSignatures`] together with items requested and proofs relative to the same
    /// ledger info.
    pub fn update_to_latest_ledger(
        &self,
        _client_known_version: u64,
        request_items: Vec<RequestItem>,
    ) -> Result<(
        Vec<ResponseItem>,
        LedgerInfoWithSignatures,
        Vec<ValidatorChangeEventWithProof>,
    )> {
       ...
        // Fulfill all request items
        let response_items = request_items
            .into_iter()
            .map(|request_item| match request_item {
                RequestItem::GetAccountState { address } => Ok(ResponseItem::GetAccountState {
                   ... //处理GetAccountState请求  query balance|sequence|account_state等命令 
                }),
                RequestItem::GetAccountTransactionBySequenceNumber {
                    account,
                    sequence_number,
                    fetch_events,
                } => {
                   ... //处理GetAccountTransactionBySequenceNumber请求 query txn_acc_seq命令
                }

                RequestItem::GetEventsByEventAccessPath {
                    access_path,
                    start_event_seq_num,
                    ascending,
                    limit,
                } => {
                   ... //query event
                }
                RequestItem::GetTransactions {
                    start_version,
                    limit,
                    fetch_events,
                } => {
                   //query txn_range命令
                }
            })
            .collect::<Result<Vec<_>>>()?;
            ...
    }

pub enum RequestItem {
    GetAccountTransactionBySequenceNumber {
        account: AccountAddress,
        sequence_number: u64,
        fetch_events: bool,
    },
    // this can't be the first variant, tracked here https://github.com/AltSysrq/proptest/issues/141
    GetAccountState {
        address: AccountAddress,
    },
    GetEventsByEventAccessPath {
        access_path: AccessPath,
        start_event_seq_num: u64,
        ascending: bool,
        limit: u64,
    },
    GetTransactions {
        start_version: Version,  
        limit: u64,
        fetch_events: bool,
    },
}

    fn get_account_state_with_proof(
        &self,
        address: AccountAddress,
        version: Version,
        ledger_version: Version,
    ) -> Result<AccountStateWithProof>