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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (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.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and
%% limitations under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developer of the Original Code is GoPivotal, Inc.
%% Copyright (c) 2007-2013 GoPivotal, Inc. All rights reserved.
%%
-module(rabbit_router).
-include_lib("stdlib/include/qlc.hrl").
-include("rabbit.hrl").
-export([match_bindings/2, match_routing_key/2]).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-export_type([routing_key/0, match_result/0]).
-type(routing_key() :: binary()).
-type(match_result() :: [rabbit_types:binding_destination()]).
-spec(match_bindings/2 :: (rabbit_types:binding_source(),
fun ((rabbit_types:binding()) -> boolean())) ->
match_result()).
-spec(match_routing_key/2 :: (rabbit_types:binding_source(),
[routing_key()] | ['_']) ->
match_result()).
-endif.
%%----------------------------------------------------------------------------
%% TODO: Maybe this should be handled by a cursor instead.
%% TODO: This causes a full scan for each entry with the same source
match_bindings(SrcName, Match) ->
Query = qlc:q([DestinationName ||
#route{binding = Binding = #binding{
source = SrcName1,
destination = DestinationName}} <-
mnesia:table(rabbit_route),
SrcName == SrcName1,
Match(Binding)]),
mnesia:async_dirty(fun qlc:e/1, [Query]).
match_routing_key(SrcName, [RoutingKey]) ->
find_routes(#route{binding = #binding{source = SrcName,
destination = '$1',
key = RoutingKey,
_ = '_'}},
[]);
match_routing_key(SrcName, [_|_] = RoutingKeys) ->
find_routes(#route{binding = #binding{source = SrcName,
destination = '$1',
key = '$2',
_ = '_'}},
[list_to_tuple(['orelse' | [{'=:=', '$2', RKey} ||
RKey <- RoutingKeys]])]).
%%--------------------------------------------------------------------
%% Normally we'd call mnesia:dirty_select/2 here, but that is quite
%% expensive for the same reasons as above, and, additionally, due to
%% mnesia 'fixing' the table with ets:safe_fixtable/2, which is wholly
%% unnecessary. According to the ets docs (and the code in erl_db.c),
%% 'select' is safe anyway ("Functions that internally traverse over a
%% table, like select and match, will give the same guarantee as
%% safe_fixtable.") and, furthermore, even the lower level iterators
%% ('first' and 'next') are safe on ordered_set tables ("Note that for
%% tables of the ordered_set type, safe_fixtable/2 is not necessary as
%% calls to first/1 and next/2 will always succeed."), which
%% rabbit_route is.
find_routes(MatchHead, Conditions) ->
ets:select(rabbit_route, [{MatchHead, Conditions, ['$1']}]).
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