Use ICU to compare POSTed view keys when necessary
It's possible for user-supplied view keys to compare equal under ICU
collation but not under Erlang's =:=. Since dict uses =:= for equality
this will result in runtime errors unless we fall back to ICU when
necessary and appropriate.
COUCHDB-2932
diff --git a/src/fabric_view_map.erl b/src/fabric_view_map.erl
index 3853d3e..7e27637 100644
--- a/src/fabric_view_map.erl
+++ b/src/fabric_view_map.erl
@@ -140,37 +140,97 @@
query_args = #mrargs{direction = Dir},
counters = Counters0,
rows = Rows0,
- keys = KeyDict,
+ keys = KeyDict0,
collation = Collation
} = State,
- Rows = merge_row(
+ {Rows, KeyDict} = merge_row(
Dir,
Collation,
- KeyDict,
+ KeyDict0,
Row#view_row{worker={Worker, From}},
Rows0
),
Counters1 = fabric_dict:update_counter(Worker, 1, Counters0),
- State1 = State#collector{rows=Rows, counters=Counters1},
+ State1 = State#collector{rows=Rows, counters=Counters1, keys=KeyDict},
fabric_view:maybe_send_row(State1);
handle_message(complete, Worker, State) ->
Counters = fabric_dict:update_counter(Worker, 1, State#collector.counters),
fabric_view:maybe_send_row(State#collector{counters = Counters}).
-merge_row(Dir, Collation, undefined, Row, Rows) ->
- lists:merge(fun(#view_row{key=KeyA, id=IdA}, #view_row{key=KeyB, id=IdB}) ->
- compare(Dir, Collation, {KeyA, IdA}, {KeyB, IdB})
- 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).
+merge_row(Dir, Collation, undefined, Row, Rows0) ->
+ Rows1 = lists:merge(
+ fun(#view_row{key=KeyA, id=IdA}, #view_row{key=KeyB, id=IdB}) ->
+ compare(Dir, Collation, {KeyA, IdA}, {KeyB, IdB})
+ end,
+ [Row],
+ Rows0
+ ),
+ {Rows1, undefined};
+merge_row(Dir, Collation, KeyDict0, Row, Rows0) ->
+ CmpFun = case Collation of
+ <<"raw">> ->
+ fun (A, A) -> 0;
+ (A, B) -> case A < B of
+ true -> -1;
+ false -> 1
+ end
+ end;
+ _ ->
+ fun couch_ejson_compare:less/2
+ end,
+ case maybe_update_keydict(Row#view_row.key, KeyDict0, CmpFun) of
+ undefined ->
+ {Rows0, KeyDict0};
+ KeyDict1 ->
+ Rows1 = lists:merge(
+ fun(#view_row{key=A, id=IdA}, #view_row{key=B, id=IdB}) ->
+ case {Dir, CmpFun(A, B)} of
+ {fwd, 0} ->
+ IdA < IdB;
+ {rev, 0} ->
+ IdB < IdA;
+ {fwd, _} ->
+ dict:fetch(A, KeyDict1) < dict:fetch(B, KeyDict1);
+ {rev, _} ->
+ dict:fetch(B, KeyDict1) < dict:fetch(A, KeyDict1)
+ end
+ end,
+ [Row],
+ Rows0
+ ),
+ {Rows1, KeyDict1}
+ end.
compare(_, _, A, A) -> true;
compare(fwd, <<"raw">>, A, B) -> A < B;
compare(rev, <<"raw">>, A, B) -> B < A;
compare(fwd, _, A, B) -> couch_ejson_compare:less_json_ids(A, B);
compare(rev, _, A, B) -> couch_ejson_compare:less_json_ids(B, A).
+
+% KeyDict captures the user-supplied ordering of keys POSTed by the user by
+% mapping to integers (see fabric_view:keydict/1). It's possible that these keys
+% do not compare equal (i.e., =:=, used by dict) to those returned by the view
+% but are in fact equal under ICU. In this case (assuming the view uses ICU
+% collation) we must update KeyDict with a mapping from the ICU-equal key to its
+% appropriate value.
+maybe_update_keydict(Key, KeyDict, CmpFun) ->
+ case dict:find(Key, KeyDict) of
+ {ok, _} ->
+ KeyDict;
+ error ->
+ case key_index(Key, dict:to_list(KeyDict), CmpFun) of
+ undefined ->
+ undefined;
+ Value ->
+ dict:store(Key, Value, KeyDict)
+ end
+ end.
+
+key_index(_, [], _) ->
+ undefined;
+key_index(KeyA, [{KeyB, Value}|KVs], CmpFun) ->
+ case CmpFun(KeyA, KeyB) of
+ 0 -> Value;
+ _ -> key_index(KeyA, KVs, CmpFun)
+ end.
