-type sender_type() :: fsm | server | raw.

-type sender() :: {sender_type(), reference() | tuple(),
                   pid()} |
                  {fsm, undefined, pid()} |
                  {server, undefined, undefined} |
                  ignore.

                                           %% TODO: Double-check that these special cases are kosher

                                              % what are these special cases and what is the reference used for??

 % special case in riak_core_vnode_master.erl

-type partition() :: chash:index_as_int().

-type vnode_req() :: term().

-type keyspaces() :: [{partition(), [partition()]}].

-record(riak_vnode_req_v1,
        {index :: partition() | undefined,
         sender = ignore :: sender(),
         request :: vnode_req()}).

-record(riak_coverage_req_v1,
        {index :: partition(),
         keyspaces :: keyspaces(),
         sender = ignore :: sender(),
         request :: vnode_req()}).

-record(riak_core_fold_req_v1,
        {foldfun :: fun(), acc0 :: term()}).

-record(riak_core_fold_req_v2,
        {foldfun :: fun(),
         acc0 :: term(),
         forwardable :: boolean(),
         opts = [] :: list()}).

-define(KV_VNODE_LOCK(Idx), {vnode_lock, Idx}).

-type
     handoff_dest() :: {riak_core_handoff_manager:ho_type(),
                        {partition(), node()}}.

%% An integer, and the number of bits to shift it left to treat it as
%% a mask in the 2^160 key space
%%
%% For a more thorough explanation of how these structures are used,
%% see `riak_core_coverage_plan'.
-type subpartition() :: {non_neg_integer(),
                         pos_integer()}.

-record(vnode_coverage,
        {vnode_identifier = 0 :: non_neg_integer(),
         partition_filters = [] :: [non_neg_integer()],
         subpartition = undefined ::
             undefined | subpartition()}).

-type vnode_selector() :: all | allup.

-type vnode_coverage() :: #vnode_coverage{}.