1 files changed, 148 insertions, 0 deletions
diff --git a/src/fabric_view_map.erl b/src/fabric_view_map.erl
new file mode 100644
index 00000000..6ec7dfde
--- /dev/null
+++ b/src/fabric_view_map.erl
@@ -0,0 +1,148 @@
+-module(fabric_view_map).
+
+-export([go/5]).
+
+-include("fabric.hrl").
+
+go(DbName, {GroupId, View}, Args, Callback, Acc0) ->
+    {ok, DDoc} = fabric:open_doc(DbName, <<"_design/", GroupId/binary>>, []),
+    Workers = lists:map(fun(#shard{name=Name, node=Node} = Shard) ->
+        Ref = rexi:cast(Node, {fabric_rpc, map_view, [Name, DDoc, View, Args]}),
+        Shard#shard{ref = Ref}
+    end, partitions:all_parts(DbName)),
+    BufferSize = couch_config:get("fabric", "map_buffer_size", "2"),
+    #view_query_args{limit = Limit, skip = Skip, keys = Keys} = Args,
+    State = #collector{
+        query_args = Args,
+        callback = Callback,
+        buffer_size = list_to_integer(BufferSize),
+        counters = fabric_dict:init(Workers, 0),
+        skip = Skip,
+        limit = Limit,
+        stop_fun = stop_fun(Args),
+        keydict = fabric_view:keydict(Keys),
+        user_acc = Acc0
+    },
+    try fabric_util:receive_loop(Workers, #shard.ref, fun handle_message/3,
+        State, infinity, 5000) of
+    {ok, NewState} ->
+        {ok, NewState#collector.user_acc};
+    Error ->
+        Error
+    after
+        fabric_util:cleanup(Workers)
+    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({total_and_offset, Tot, Off}, {Worker, From}, State) ->
+    #collector{
+        callback = Callback,
+        counters = Counters0,
+        total_rows = Total0,
+        offset = Offset0,
+        user_acc = AccIn
+    } = State,
+    case fabric_dict:lookup_element(Worker, Counters0) of
+    undefined ->
+        % this worker lost the race with other partition copies, terminate
+        gen_server:reply(From, stop),
+        {ok, State};
+    0 ->
+        gen_server:reply(From, ok),
+        Counters1 = fabric_dict:update_counter(Worker, 1, Counters0),
+        Counters2 = fabric_view:remove_overlapping_shards(Worker, Counters1),
+        Total = Total0 + Tot,
+        Offset = Offset0 + Off,
+        case fabric_dict:any(0, Counters2) of
+        true ->
+            {ok, State#collector{
+                counters = Counters2,
+                total_rows = Total,
+                offset = Offset
+            }};
+        false ->
+            FinalOffset = erlang:min(Total, Offset+State#collector.skip),
+            {Go, Acc} = Callback({total_and_offset, Total, FinalOffset}, AccIn),
+            {Go, State#collector{
+                counters = fabric_dict:decrement_all(Counters2),
+                total_rows = Total,
+                offset = FinalOffset,
+                user_acc = Acc
+            }}
+        end
+    end;
+
+handle_message(#view_row{} = Row, {Worker, From}, State) ->
+    #collector{
+        query_args = #view_query_args{direction=Dir},
+        counters = Counters0,
+        rows = Rows0,
+        keydict = KeyDict
+    } = State,
+    Rows = merge_row(Dir, KeyDict, Row#view_row{worker=Worker}, Rows0),
+    Counters1 = fabric_dict:update_counter(Worker, 1, Counters0),
+    State1 = State#collector{rows=Rows, counters=Counters1},
+    State2 = fabric_view:maybe_pause_worker(Worker, From, State1),
+    fabric_view:maybe_send_row(State2);
+
+handle_message(complete, Worker, State) ->
+    Counters = fabric_dict:update_counter(Worker, 1, State#collector.counters),
+    fabric_view:maybe_send_row(State#collector{counters = Counters}).
+
+stop_fun(#view_query_args{} = QueryArgs) ->
+    #view_query_args{
+        direction = Dir,
+        inclusive_end = Inclusive,
+        end_key = EndKey,
+        end_docid = EndDocId
+    } = QueryArgs,
+    stop_fun(Dir, Inclusive, EndKey, EndDocId).
+
+stop_fun(fwd, true, EndKey, EndDocId) ->
+    fun(#view_row{key=Key, id=Id}) ->
+        couch_view:less_json([EndKey, EndDocId], [Key, Id])
+    end;
+stop_fun(fwd, false, EndKey, EndDocId) ->
+    fun(#view_row{key=K}) when K==EndKey -> true; (#view_row{key=Key, id=Id}) ->
+        couch_view:less_json([EndKey, EndDocId], [Key, Id])
+    end;
+stop_fun(rev, true, EndKey, EndDocId) ->
+    fun(#view_row{key=Key, id=Id}) ->
+        couch_view:less_json([Key, Id], [EndKey, EndDocId])
+    end;
+stop_fun(rev, false, EndKey, EndDocId) ->
+    fun(#view_row{key=K}) when K==EndKey -> true; (#view_row{key=Key, id=Id}) ->
+        couch_view:less_json([Key, Id], [EndKey, EndDocId])
+    end.
+
+merge_row(fwd, undefined, Row, Rows) ->
+    lists:merge(fun(#view_row{key=KeyA, id=IdA}, #view_row{key=KeyB, id=IdB}) ->
+        couch_view:less_json([KeyA, IdA], [KeyB, IdB])
+    end, [Row], Rows);
+merge_row(rev, undefined, Row, Rows) ->
+    lists:merge(fun(#view_row{key=KeyA, id=IdA}, #view_row{key=KeyB, id=IdB}) ->
+        couch_view:less_json([KeyB, IdB], [KeyA, IdA])
+    end, [Row], Rows);
+merge_row(_, KeyDict, Row, Rows) ->
+    lists:merge(fun(#view_row{key=A, id=IdA}, #view_row{key=B, id=IdB}) ->
+        if A =:= B -> IdA < IdB; true ->
+            dict:fetch(A, KeyDict) < dict:fetch(B, KeyDict)
+        end
+    end, [Row], Rows).
+