Function tikv::storage::prepare_snap_ctx

fn prepare_snap_ctx<'a>(
    pb_ctx: &'a Context, 
    keys: impl IntoIterator<Item = &'a Key> + Clone, 
    start_ts: TimeStamp, 
    bypass_locks: &'a TsSet, 
    concurrency_manager: &ConcurrencyManager, 
    cmd: CommandKind
) -> Result<SnapContext<'a>>