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% Copyright 2010 Cloudant
%
% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(fabric_doc_open).
-export([go/3]).
-include("fabric.hrl").
-include_lib("mem3/include/mem3.hrl").
-include_lib("couch/include/couch_db.hrl").
go(DbName, Id, Options) ->
Workers = fabric_util:submit_jobs(mem3:shards(DbName,Id), open_doc,
[Id, [deleted|Options]]),
SuppressDeletedDoc = not lists:member(deleted, Options),
R = couch_util:get_value(r, Options, couch_config:get("cluster","r","2")),
Acc0 = {length(Workers), list_to_integer(R), []},
case fabric_util:recv(Workers, #shard.ref, fun handle_message/3, Acc0) of
{ok, {ok, #doc{deleted=true}}} when SuppressDeletedDoc ->
{not_found, deleted};
{ok, Else} ->
Else;
Error ->
Error
end.
handle_message({rexi_DOWN, _, _, _}, _Worker, Acc0) ->
skip_message(Acc0);
handle_message({rexi_EXIT, _Reason}, _Worker, Acc0) ->
skip_message(Acc0);
handle_message(Reply, _Worker, {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.
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.
make_key({ok, #doc{id=Id, revs=Revs}}) ->
{Id, Revs};
make_key(Else) ->
Else.
repair_read_quorum_failure(Replies) ->
case [Doc || {_Key, {ok, Doc}, _Count} <- 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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