1 files changed, 60 insertions, 0 deletions
diff --git a/deps/rabbitmq_sharding/src/rabbit_sharding_exchange_type_modulus_hash.erl b/deps/rabbitmq_sharding/src/rabbit_sharding_exchange_type_modulus_hash.erl
new file mode 100644
index 0000000000..0509972757
--- /dev/null
+++ b/deps/rabbitmq_sharding/src/rabbit_sharding_exchange_type_modulus_hash.erl
@@ -0,0 +1,60 @@
+%% This Source Code Form is subject to the terms of the Mozilla Public
+%% License, v. 2.0. If a copy of the MPL was not distributed with this
+%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
+%%
+%% Copyright (c) 2007-2020 VMware, Inc. or its affiliates.  All rights reserved.
+%%
+
+-module(rabbit_sharding_exchange_type_modulus_hash).
+
+-include_lib("rabbit_common/include/rabbit.hrl").
+
+-behaviour(rabbit_exchange_type).
+
+-export([description/0, serialise_events/0, route/2, info/1, info/2]).
+-export([validate/1, validate_binding/2,
+         create/2, delete/3, policy_changed/2,
+         add_binding/3, remove_bindings/3, assert_args_equivalence/2]).
+
+-rabbit_boot_step(
+   {rabbit_sharding_exchange_type_modulus_hash_registry,
+    [{description, "exchange type x-modulus-hash: registry"},
+     {mfa,         {rabbit_registry, register,
+                    [exchange, <<"x-modulus-hash">>, ?MODULE]}},
+     {cleanup, {rabbit_registry, unregister,
+                [exchange, <<"x-modulus-hash">>]}},
+     {requires,    rabbit_registry},
+     {enables,     kernel_ready}]}).
+
+-define(PHASH2_RANGE, 134217728). %% 2^27
+
+description() ->
+    [{description, <<"Modulus Hashing Exchange">>}].
+
+serialise_events() -> false.
+
+route(#exchange{name = Name},
+      #delivery{message = #basic_message{routing_keys = Routes}}) ->
+    Qs = rabbit_router:match_routing_key(Name, ['_']),
+    case length(Qs) of
+        0 -> [];
+        N -> [lists:nth(hash_mod(Routes, N), Qs)]
+    end.
+
+info(_) -> [].
+
+info(_, _) -> [].
+
+validate(_X) -> ok.
+validate_binding(_X, _B) -> ok.
+create(_Tx, _X) -> ok.
+delete(_Tx, _X, _Bs) -> ok.
+policy_changed(_X1, _X2) -> ok.
+add_binding(_Tx, _X, _B) -> ok.
+remove_bindings(_Tx, _X, _Bs) -> ok.
+assert_args_equivalence(X, Args) ->
+    rabbit_exchange:assert_args_equivalence(X, Args).
+
+hash_mod(Routes, N) ->
+    M = erlang:phash2(Routes, ?PHASH2_RANGE) rem N,
+    M + 1. %% erlang lists are 1..N indexed.