1 files changed, 85 insertions, 0 deletions
diff --git a/apps/fabric/src/fabric_view_reduce.erl b/apps/fabric/src/fabric_view_reduce.erl
new file mode 100644
index 00000000..ddde9f22
--- /dev/null
+++ b/apps/fabric/src/fabric_view_reduce.erl
@@ -0,0 +1,85 @@
+-module(fabric_view_reduce).
+
+-export([go/6]).
+
+-include("fabric.hrl").
+-include_lib("mem3/include/mem3.hrl").
+-include_lib("couch/include/couch_db.hrl").
+
+go(DbName, GroupId, View, Args, Callback, Acc0) when is_binary(GroupId) ->
+    {ok, DDoc} = fabric:open_doc(DbName, <<"_design/", GroupId/binary>>, []),
+    go(DbName, DDoc, View, Args, Callback, Acc0);
+
+go(DbName, DDoc, VName, Args, Callback, Acc0) ->
+    #group{def_lang=Lang, views=Views} = Group =
+        couch_view_group:design_doc_to_view_group(#db{name=DbName}, DDoc),
+    {NthRed, View} = fabric_view:extract_view(nil, VName, Views, reduce),
+    {VName, RedSrc} = lists:nth(NthRed, View#view.reduce_funs),
+    Workers = lists:map(fun(#shard{name=Name, node=N} = Shard) ->
+        Ref = rexi:cast(N, {fabric_rpc, reduce_view, [Name,Group,VName,Args]}),
+        Shard#shard{ref = Ref}
+    end, mem3:shards(DbName)),
+    BufferSize = couch_config:get("fabric", "reduce_buffer_size", "20"),
+    #view_query_args{limit = Limit, skip = Skip} = Args,
+    State = #collector{
+        query_args = Args,
+        callback = Callback,
+        buffer_size = list_to_integer(BufferSize),
+        counters = fabric_dict:init(Workers, 0),
+        keys = Args#view_query_args.keys,
+        skip = Skip,
+        limit = Limit,
+        lang = Group#group.def_lang,
+        os_proc = couch_query_servers:get_os_process(Lang),
+        reducer = RedSrc,
+        rows = dict:new(),
+        user_acc = Acc0
+    },
+    try fabric_util:receive_loop(Workers, #shard.ref, fun handle_message/3,
+        State, infinity, 1000 * 60 * 60) of
+    {ok, NewState} ->
+        {ok, NewState#collector.user_acc};
+    Error ->
+        Error
+    after
+        fabric_util:cleanup(Workers),
+        catch couch_query_servers:ret_os_process(State#collector.os_proc)
+    end.
+
+handle_message({rexi_DOWN, _, _, _}, nil, State) ->
+    % TODO see if progress can be made here, possibly by removing all shards
+    % from that node and checking is_progress_possible
+    {ok, State};
+
+handle_message({rexi_EXIT, Reason}, Worker, State) ->
+    ?LOG_ERROR("~p rexi_EXIT ~p", [?MODULE, Reason]),
+    #collector{callback=Callback, counters=Counters0, user_acc=Acc} = State,
+    Counters = fabric_dict:erase(Worker, Counters0),
+    case fabric_view:is_progress_possible(Counters) of
+    true ->
+        {ok, State#collector{counters = Counters}};
+    false ->
+        Callback({error, dead_shards}, Acc),
+        {error, dead_shards}
+    end;
+
+handle_message(#view_row{key=Key} = Row, {Worker, From}, State) ->
+    #collector{counters = Counters0, rows = Rows0} = State,
+    case fabric_dict:lookup_element(Worker, Counters0) of
+    undefined ->
+        % this worker lost the race with other partition copies, terminate it
+        gen_server:reply(From, stop),
+        {ok, State};
+    _ ->
+        Rows = dict:append(Key, Row#view_row{worker=Worker}, Rows0),
+        C1 = fabric_dict:update_counter(Worker, 1, Counters0),
+        % TODO time this call, if slow don't do it every time
+        C2 = fabric_view:remove_overlapping_shards(Worker, C1),
+        State1 = State#collector{rows=Rows, counters=C2},
+        State2 = fabric_view:maybe_pause_worker(Worker, From, State1),
+        fabric_view:maybe_send_row(State2)
+    end;
+
+handle_message(complete, Worker, State) ->
+    Counters = fabric_dict:update_counter(Worker, 1, State#collector.counters),
+    fabric_view:maybe_send_row(State#collector{counters = Counters}).