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-module(fabric_doc).
-export([open_doc/3, open_revs/4, get_missing_revs/2, update_docs/3]).
-include("../../couch/src/couch_db.hrl").
-include("../../dynomite/include/membership.hrl").
open_doc(DbName, Id, Options) ->
Workers = fabric_util:submit_jobs(partitions:for_key(DbName,Id), open_doc,
[Id, Options]),
SuppressDeletedDoc = not lists:member(deleted, Options),
Acc0 = {length(Workers), couch_util:get_value(r, Options, 1), []},
case fabric_util:recv(Workers, #shard.ref, fun handle_open_doc/3, Acc0) of
{ok, #doc{deleted=true}} when SuppressDeletedDoc ->
{not_found, deleted};
{ok, {not_found, missing}} ->
{not_found, missing};
Else ->
Else
end.
open_revs(DbName, Id, Revs, Options) ->
Workers = fabric_util:submit_jobs(partitions:for_key(DbName,Id), open_revs,
[Id, Revs, Options]),
Acc0 = {length(Workers), couch_util:get_value(r, Options, 1), []},
fabric_util:recv(Workers, #shard.ref, fun handle_open_revs/3, Acc0).
update_docs(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_update_docs/3, Acc0) of
{ok, Results} ->
{ok, couch_util:reorder_results(AllDocs, Results)};
Else ->
Else
end.
get_missing_revs(_DbName, _IdsRevs) ->
ok.
handle_open_doc(_Worker, {rexi_DOWN, _, _, _}, Acc0) ->
skip_message(Acc0);
handle_open_doc(_Worker, {rexi_EXIT, _Reason}, Acc0) ->
skip_message(Acc0);
handle_open_doc(_Worker, Reply, {WaitingCount, R, Replies}) ->
case merge_read_reply(make_key(Reply), Reply, Replies) of
{_, KeyCount} when KeyCount =:= R ->
{stop, Reply};
{NewReplies, KeyCount} when KeyCount < R ->
if WaitingCount =:= 1 ->
% last message arrived, but still no quorum
repair_read_quorum_failure(NewReplies);
true ->
{ok, {WaitingCount-1, R, NewReplies}}
end
end.
handle_open_revs(_Worker, {rexi_DOWN, _, _, _}, Acc0) ->
skip_message(Acc0);
handle_open_revs(_Worker, {rexi_EXIT, _}, Acc0) ->
skip_message(Acc0);
handle_open_revs(_Worker, _Reply, {_WaitingCount, _R, _Replies}) ->
{stop, not_implemented}.
handle_update_docs(_Worker, {rexi_DOWN, _, _, _}, Acc0) ->
skip_message(Acc0);
handle_update_docs(_Worker, {rexi_EXIT, _}, Acc0) ->
skip_message(Acc0);
handle_update_docs(Worker, {ok, Replies}, 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_update_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_update_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_update_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_update_reply(_, _, continue) ->
% we didn't meet quorum for all docs, so we're fast-forwarding the fold
continue;
maybe_update_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)).
skip_message({1, _R, Replies}) ->
repair_read_quorum_failure(Replies);
skip_message({WaitingCount, R, Replies}) ->
{ok, {WaitingCount-1, R, Replies}}.
merge_read_reply(Key, Reply, Replies) ->
case lists:keyfind(Key, 1, Replies) of
false ->
{[{Key, Reply, 1} | Replies], 1};
{Key, _, N} ->
{lists:keyreplace(Key, 1, Replies, {Key, Reply, N+1}), N+1}
end.
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)).
make_key({ok, #doc{id=Id, revs=Revs}}) ->
{Id, Revs};
make_key({not_found, missing}) ->
{not_found, missing}.
repair_read_quorum_failure(Replies) ->
case [Doc || {ok, Doc} <- Replies] of
[] ->
{stop, {not_found, missing}};
[Doc|_] ->
% TODO merge docs to find the winner as determined by replication
{stop, {ok, Doc}}
end.
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