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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) 2007-2014 GoPivotal, Inc. All rights reserved.
%%
-module(rabbit_dead_letter).
-export([publish/5]).
-include("rabbit.hrl").
-include("rabbit_framing.hrl").
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-type reason() :: 'expired' | 'rejected' | 'maxlen'.
-spec publish(rabbit_types:message(), reason(), rabbit_types:exchange(),
'undefined' | binary(), rabbit_amqqueue:name()) -> 'ok'.
-endif.
%%----------------------------------------------------------------------------
publish(Msg, Reason, X, RK, QName) ->
DLMsg = make_msg(Msg, Reason, X#exchange.name, RK, QName),
Delivery = rabbit_basic:delivery(false, false, DLMsg, undefined),
{Queues, Cycles} = detect_cycles(Reason, DLMsg,
rabbit_exchange:route(X, Delivery)),
lists:foreach(fun log_cycle_once/1, Cycles),
rabbit_amqqueue:deliver(rabbit_amqqueue:lookup(Queues), Delivery),
ok.
make_msg(Msg = #basic_message{content = Content,
exchange_name = Exchange,
routing_keys = RoutingKeys},
Reason, DLX, RK, #resource{name = QName}) ->
{DeathRoutingKeys, HeadersFun1} =
case RK of
undefined -> {RoutingKeys, fun (H) -> H end};
_ -> {[RK], fun (H) -> lists:keydelete(<<"CC">>, 1, H) end}
end,
ReasonBin = list_to_binary(atom_to_list(Reason)),
TimeSec = rabbit_misc:now_ms() div 1000,
PerMsgTTL = per_msg_ttl_header(Content#content.properties),
HeadersFun2 =
fun (Headers) ->
%% The first routing key is the one specified in the
%% basic.publish; all others are CC or BCC keys.
RKs = [hd(RoutingKeys) | rabbit_basic:header_routes(Headers)],
RKs1 = [{longstr, Key} || Key <- RKs],
Info = [{<<"reason">>, longstr, ReasonBin},
{<<"queue">>, longstr, QName},
{<<"time">>, timestamp, TimeSec},
{<<"exchange">>, longstr, Exchange#resource.name},
{<<"routing-keys">>, array, RKs1}] ++ PerMsgTTL,
HeadersFun1(rabbit_basic:prepend_table_header(<<"x-death">>,
Info, Headers))
end,
Content1 = #content{properties = Props} =
rabbit_basic:map_headers(HeadersFun2, Content),
Content2 = Content1#content{properties =
Props#'P_basic'{expiration = undefined}},
Msg#basic_message{exchange_name = DLX,
id = rabbit_guid:gen(),
routing_keys = DeathRoutingKeys,
content = Content2}.
per_msg_ttl_header(#'P_basic'{expiration = undefined}) ->
[];
per_msg_ttl_header(#'P_basic'{expiration = Expiration}) ->
[{<<"original-expiration">>, longstr, Expiration}];
per_msg_ttl_header(_) ->
[].
detect_cycles(rejected, _Msg, Queues) ->
{Queues, []};
detect_cycles(_Reason, #basic_message{content = Content}, Queues) ->
#content{properties = #'P_basic'{headers = Headers}} =
rabbit_binary_parser:ensure_content_decoded(Content),
NoCycles = {Queues, []},
case Headers of
undefined ->
NoCycles;
_ ->
case rabbit_misc:table_lookup(Headers, <<"x-death">>) of
{array, Deaths} ->
{Cycling, NotCycling} =
lists:partition(fun (#resource{name = Queue}) ->
is_cycle(Queue, Deaths)
end, Queues),
OldQueues = [rabbit_misc:table_lookup(D, <<"queue">>) ||
{table, D} <- Deaths],
OldQueues1 = [QName || {longstr, QName} <- OldQueues],
{NotCycling, [[QName | OldQueues1] ||
#resource{name = QName} <- Cycling]};
_ ->
NoCycles
end
end.
is_cycle(Queue, Deaths) ->
{Cycle, Rest} =
lists:splitwith(
fun ({table, D}) ->
{longstr, Queue} =/= rabbit_misc:table_lookup(D, <<"queue">>);
(_) ->
true
end, Deaths),
%% Is there a cycle, and if so, is it "fully automatic", i.e. with
%% no reject in it?
case Rest of
[] -> false;
[H|_] -> lists:all(
fun ({table, D}) ->
{longstr, <<"rejected">>} =/=
rabbit_misc:table_lookup(D, <<"reason">>);
(_) ->
%% There was something we didn't expect, therefore
%% a client must have put it there, therefore the
%% cycle was not "fully automatic".
false
end, Cycle ++ [H])
end.
log_cycle_once(Queues) ->
Key = {queue_cycle, Queues},
case get(Key) of
true -> ok;
undefined -> rabbit_log:warning(
"Message dropped. Dead-letter queues cycle detected" ++
": ~p~nThis cycle will NOT be reported again.~n",
[Queues]),
put(Key, true)
end.
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