Make exchanges modular behaviours. Added

rabbit_exchange_behaviour. Split fanout, direct, topic and headers
into new modules that implement the new behaviour. Added convention
that for exchange type X, a module named rabbit_exchange_type_X must
exist.

1 files changed, 93 insertions, 0 deletions

diff --git a/src/rabbit_exchange_type_headers.erl b/src/rabbit_exchange_type_headers.erl
new file mode 100644
index 00000000..e539aca4
--- /dev/null
+++ b/src/rabbit_exchange_type_headers.erl
@@ -0,0 +1,93 @@
+-module(rabbit_exchange_type_headers).
+-include("rabbit.hrl").
+-include("rabbit_framing.hrl").
+
+-behaviour(rabbit_exchange_behaviour).
+
+-export([description/0, route/3]).
+-export([recover/1, init/1, delete/1, add_binding/2, delete_binding/2]).
+
+-ifdef(use_specs).
+-spec(headers_match/2 :: (amqp_table(), amqp_table()) -> boolean()).
+-endif.
+
+description() ->
+    [{name, <<"headers">>},
+     {description, <<"AMQP headers exchange, as per the AMQP specification">>}].
+
+route(#exchange{name = Name}, _RoutingKey, Content) ->
+    Headers = case (Content#content.properties)#'P_basic'.headers of
+                  undefined -> [];
+                  H         -> rabbit_misc:sort_arguments(H)
+              end,
+    rabbit_router:match_bindings(Name, fun (#binding{args = Spec}) ->
+                                               headers_match(Spec, Headers)
+                                       end).
+
+default_headers_match_kind() -> all.
+
+parse_x_match(<<"all">>) -> all;
+parse_x_match(<<"any">>) -> any;
+parse_x_match(Other) ->
+    rabbit_log:warning("Invalid x-match field value ~p; expected all or any",
+                       [Other]),
+    default_headers_match_kind().
+
+%% Horrendous matching algorithm. Depends for its merge-like
+%% (linear-time) behaviour on the lists:keysort
+%% (rabbit_misc:sort_arguments) that route/3 and
+%% rabbit_exchange:{add,delete}_binding/4 do.
+%%
+%%                 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+%% In other words: REQUIRES BOTH PATTERN AND DATA TO BE SORTED ASCENDING BY KEY.
+%%                 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+%%
+headers_match(Pattern, Data) ->
+    MatchKind = case lists:keysearch(<<"x-match">>, 1, Pattern) of
+                    {value, {_, longstr, MK}} -> parse_x_match(MK);
+                    {value, {_, Type, MK}} ->
+                        rabbit_log:warning("Invalid x-match field type ~p "
+                                           "(value ~p); expected longstr",
+                                           [Type, MK]),
+                        default_headers_match_kind();
+                    _ -> default_headers_match_kind()
+                end,
+    headers_match(Pattern, Data, true, false, MatchKind).
+
+headers_match([], _Data, AllMatch, _AnyMatch, all) ->
+    AllMatch;
+headers_match([], _Data, _AllMatch, AnyMatch, any) ->
+    AnyMatch;
+headers_match([{<<"x-", _/binary>>, _PT, _PV} | PRest], Data,
+              AllMatch, AnyMatch, MatchKind) ->
+    headers_match(PRest, Data, AllMatch, AnyMatch, MatchKind);
+headers_match(_Pattern, [], _AllMatch, AnyMatch, MatchKind) ->
+    headers_match([], [], false, AnyMatch, MatchKind);
+headers_match(Pattern = [{PK, _PT, _PV} | _], [{DK, _DT, _DV} | DRest],
+              AllMatch, AnyMatch, MatchKind) when PK > DK ->
+    headers_match(Pattern, DRest, AllMatch, AnyMatch, MatchKind);
+headers_match([{PK, _PT, _PV} | PRest], Data = [{DK, _DT, _DV} | _],
+              _AllMatch, AnyMatch, MatchKind) when PK < DK ->
+    headers_match(PRest, Data, false, AnyMatch, MatchKind);
+headers_match([{PK, PT, PV} | PRest], [{DK, DT, DV} | DRest],
+              AllMatch, AnyMatch, MatchKind) when PK == DK ->
+    {AllMatch1, AnyMatch1} =
+        if
+            %% It's not properly specified, but a "no value" in a
+            %% pattern field is supposed to mean simple presence of
+            %% the corresponding data field. I've interpreted that to
+            %% mean a type of "void" for the pattern field.
+            PT == void -> {AllMatch, true};
+            %% Similarly, it's not specified, but I assume that a
+            %% mismatched type causes a mismatched value.
+            PT =/= DT  -> {false, AnyMatch};
+            PV == DV   -> {AllMatch, true};
+            true       -> {false, AnyMatch}
+        end,
+    headers_match(PRest, DRest, AllMatch1, AnyMatch1, MatchKind).
+
+recover(_X) -> ok.
+init(_X) -> ok.
+delete(_X) -> ok.
+add_binding(_X, _B) -> ok.
+delete_binding(_X, _B) -> ok.