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path: root/src/fabric_rpc.erl
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-module(fabric_rpc).

-export([get_db_info/1, get_doc_count/1, get_update_seq/1]).
-export([open_doc/3, open_revs/4, get_missing_revs/2, update_docs/3]).
-export([all_docs/2]).

-include("fabric.hrl").

-record (view_acc, {
    db,
    limit,
    include_docs,
    offset = nil,
    reduce_fun = fun couch_db:enum_docs_reduce_to_count/1,
    stop_fun,
    group_level = 0
}).

%% rpc endpoints
%%  call to with_db will supply your M:F with a #db{} and then remaining args

all_docs(DbName, #view_query_args{keys=nil} = QueryArgs) ->
    {ok, Db} = couch_db:open(DbName, []),
    #view_query_args{
        start_key = StartKey,
        start_docid = StartDocId,
        limit = Limit,
        skip = Skip,
        include_docs = IncludeDocs,
        direction = Dir
    } = QueryArgs,
    StartId = if is_binary(StartKey) -> StartKey; true -> StartDocId end,
    Acc0 = #view_acc{
        db = Db,
        include_docs = IncludeDocs,
        limit = Limit+Skip,
        stop_fun = all_docs_stop_fun(QueryArgs)
    },
    {ok, Acc} = couch_db:enum_docs(Db, StartId, Dir, fun view_fold/3, Acc0),
    if Acc#view_acc.offset == nil ->
        Total = couch_db:get_doc_count(Db),
        rexi:sync_reply({total_and_offset, Total, Total});
    true -> ok end,
    rexi:reply(complete).

get_db_info(DbName) ->
    with_db(DbName, {couch_db, get_db_info, []}).

get_doc_count(DbName) ->
    with_db(DbName, {couch_db, get_doc_count, []}).

get_update_seq(DbName) ->
    rexi:reply(case couch_db:open(DbName, []) of
    {ok, #db{update_seq = Seq}} ->
        {ok, Seq};
    Error ->
        Error
    end).

open_doc(DbName, DocId, Options) ->
    with_db(DbName, {couch_db, open_doc_int, [DocId, Options]}).

open_revs(DbName, Id, Revs, Options) ->
    with_db(DbName, {couch_db, open_doc_revs, [Id, Revs, Options]}).

get_missing_revs(DbName, IdRevsList) ->
    % reimplement here so we get [] for Ids with no missing revs in response
    rexi:reply(case couch_db:open(DbName, []) of
    {ok, Db} ->
        Ids = [Id1 || {Id1, _Revs} <- IdRevsList],
        {ok, lists:zipwith(fun({Id, Revs}, FullDocInfoResult) ->
            case FullDocInfoResult of
            {ok, #full_doc_info{rev_tree=RevisionTree}} ->
                {Id, couch_key_tree:find_missing(RevisionTree, Revs)};
            not_found ->
                {Id, Revs}
            end
        end, IdRevsList, couch_btree:lookup(Db#db.id_tree, Ids))};
    Error ->
        Error
    end).

update_docs(DbName, Docs, Options) ->
    with_db(DbName, {couch_db, update_docs, [Docs, Options]}).

%%
%% internal
%%

with_db(DbName, {M,F,A}) ->
    case couch_db:open(DbName, []) of
    {ok, Db} ->
        rexi:reply(apply(M, F, [Db | A]));
    Error ->
        rexi:reply(Error)
    end.

view_fold(#full_doc_info{} = FullDocInfo, OffsetReds, Acc) ->
    % matches for _all_docs and translates #full_doc_info{} -> KV pair
    case couch_doc:to_doc_info(FullDocInfo) of
    #doc_info{revs=[#rev_info{deleted=false, rev=Rev}|_]} ->
        Id = FullDocInfo#full_doc_info.id,
        Value = {[{rev,couch_doc:rev_to_str(Rev)}]},
        view_fold({{Id,Id}, Value}, OffsetReds, Acc);
    #doc_info{revs=[#rev_info{deleted=true}|_]} ->
        {ok, Acc}
    end;
view_fold(KV, OffsetReds, #view_acc{offset=nil} = Acc) ->
    % calculates the offset for this shard
    #view_acc{db=Db, reduce_fun=Reduce} = Acc,
    Offset = Reduce(OffsetReds),
    rexi:sync_reply({total_and_offset, couch_db:get_doc_count(Db), Offset}),
    view_fold(KV, OffsetReds, Acc#view_acc{offset=Offset});
view_fold(_KV, _Offset, #view_acc{limit=0} = Acc) ->
    % we scanned through limit+skip local rows
    {stop, Acc};
view_fold({{Key,Id}, Value}, _Offset, Acc) ->
    % the normal case
    #view_acc{
        db = Db,
        limit = Limit,
        include_docs = IncludeDocs,
        stop_fun = PassedEnd
    } = Acc,
    case PassedEnd(Key, Id) of
    true ->
        {stop, Acc};
    false ->
        RowProps = case IncludeDocs of
        true ->
            case couch_db:open_doc(Db, Id, []) of
              {not_found, missing} ->
                  [{id, Id}, {key, Key}, {value, Value}, {error, missing}];
              {not_found, deleted} ->
                  [{id, Id}, {key, Key}, {value, Value}];
              {ok, Doc} ->
                  JsonDoc = couch_doc:to_json_obj(Doc, []),
                  [{id, Id}, {key, Key}, {value, Value}, {doc, JsonDoc}]
            end;
        false ->
            [{id, Id}, {key, Key}, {value, Value}]
        end,
        rexi:sync_reply({row, RowProps}),
        {ok, Acc#view_acc{limit=Limit-1}}
    end.

all_docs_stop_fun(#view_query_args{direction=fwd, end_key=EndKey}) ->
    fun(ViewKey, _) ->
        couch_db_updater:less_docid(EndKey, ViewKey)
    end;
all_docs_stop_fun(#view_query_args{direction=rev, end_key=EndKey}) ->
    fun(ViewKey, _) ->
        couch_db_updater:less_docid(ViewKey, EndKey)
    end.