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-module(fabric_update_docs).
-export([go/3]).
-include("fabric.hrl").
go(DbName, AllDocs, Options) ->
GroupedDocs = lists:map(fun({#shard{name=Name, node=Node} = Shard, Docs}) ->
Ref = rexi:cast(Node, {fabric_rpc, update_docs, [Name, Docs, Options]}),
{Shard#shard{ref=Ref}, Docs}
end, group_docs_by_shard(DbName, AllDocs)),
{Workers, _} = lists:unzip(GroupedDocs),
Acc0 = {length(Workers), length(AllDocs), couch_util:get_value(w, Options, 1),
GroupedDocs, dict:new()},
case fabric_util:recv(Workers, #shard.ref, fun handle_message/3, Acc0) of
{ok, Results} ->
{ok, couch_util:reorder_results(AllDocs, Results)};
Else ->
Else
end.
handle_message({rexi_DOWN, _, _, _}, _Worker, Acc0) ->
skip_message(Acc0);
handle_message({rexi_EXIT, _}, _Worker, Acc0) ->
skip_message(Acc0);
handle_message({ok, Replies}, Worker, Acc0) ->
{WaitingCount, DocCount, W, GroupedDocs, DocReplyDict0} = Acc0,
Docs = couch_util:get_value(Worker, GroupedDocs),
DocReplyDict = append_update_replies(Docs, Replies, DocReplyDict0),
case {WaitingCount, dict:size(DocReplyDict)} of
{1, _} ->
% last message has arrived, we need to conclude things
{W, Reply} = dict:fold(fun force_reply/3, {W,[]}, DocReplyDict),
{stop, Reply};
{_, DocCount} ->
% we've got at least one reply for each document, let's take a look
case dict:fold(fun maybe_reply/3, {stop,W,[]}, DocReplyDict) of
continue ->
{ok, {WaitingCount - 1, DocCount, W, GroupedDocs, DocReplyDict}};
{stop, W, FinalReplies} ->
{stop, FinalReplies}
end;
{_, N} when N < DocCount ->
% no point in trying to finalize anything yet
{ok, {WaitingCount - 1, DocCount, W, GroupedDocs, DocReplyDict}}
end.
force_reply(Doc, Replies, {W, Acc}) ->
% TODO make a real decision here
case Replies of
[] ->
{W, [{Doc, {error, internal_server_error}} | Acc]};
[Reply| _] ->
{W, [{Doc, Reply} | Acc]}
end.
maybe_reply(_, _, continue) ->
% we didn't meet quorum for all docs, so we're fast-forwarding the fold
continue;
maybe_reply(Doc, Replies, {stop, W, Acc}) ->
case update_quorum_met(W, Replies) of
{true, Reply} ->
{stop, W, [{Doc, Reply} | Acc]};
false ->
continue
end.
update_quorum_met(W, Replies) ->
% TODO make a real decision here
case length(Replies) >= W of
true ->
{true, hd(Replies)};
false ->
false
end.
-spec group_docs_by_shard(binary(), [#doc{}]) -> [{#shard{}, [#doc{}]}].
group_docs_by_shard(DbName, Docs) ->
dict:to_list(lists:foldl(fun(#doc{id=Id} = Doc, D0) ->
lists:foldl(fun(Shard, D1) ->
dict:append(Shard, Doc, D1)
end, D0, partitions:for_key(DbName,Id))
end, dict:new(), Docs)).
append_update_replies([], [], DocReplyDict) ->
DocReplyDict;
append_update_replies([Doc|Rest1], [Reply|Rest2], Dict0) ->
% TODO what if the same document shows up twice in one update_docs call?
append_update_replies(Rest1, Rest2, dict:append(Doc, Reply, Dict0)).
skip_message(Acc0) ->
% TODO fix this
{ok, Acc0}.
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