1%% This Source Code Form is subject to the terms of the Mozilla Public
2%% License, v. 2.0. If a copy of the MPL was not distributed with this
3%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
4%%
5%% Copyright (c) 2007-2021 VMware, Inc. or its affiliates.  All rights reserved.
6%%
7
8-module(rabbit_queue_decorator).
9
10-include_lib("rabbit_common/include/rabbit.hrl").
11-include("amqqueue.hrl").
12
13-export([select/1, set/1, register/2, unregister/1]).
14
15-behaviour(rabbit_registry_class).
16
17-export([added_to_rabbit_registry/2, removed_from_rabbit_registry/1]).
18
19%%----------------------------------------------------------------------------
20
21-callback startup(amqqueue:amqqueue()) -> 'ok'.
22
23-callback shutdown(amqqueue:amqqueue()) -> 'ok'.
24
25-callback policy_changed(amqqueue:amqqueue(), amqqueue:amqqueue()) ->
26    'ok'.
27
28-callback active_for(amqqueue:amqqueue()) -> boolean().
29
30%% called with Queue, MaxActivePriority, IsEmpty
31-callback consumer_state_changed(
32            amqqueue:amqqueue(), integer(), boolean()) -> 'ok'.
33
34%%----------------------------------------------------------------------------
35
36added_to_rabbit_registry(_Type, _ModuleName) -> ok.
37removed_from_rabbit_registry(_Type) -> ok.
38
39select(Modules) ->
40    [M || M <- Modules, code:which(M) =/= non_existing].
41
42set(Q) when ?is_amqqueue(Q) ->
43    Decorators = [D || D <- list(), D:active_for(Q)],
44    amqqueue:set_decorators(Q, Decorators).
45
46list() -> [M || {_, M} <- rabbit_registry:lookup_all(queue_decorator)].
47
48register(TypeName, ModuleName) ->
49    rabbit_registry:register(queue_decorator, TypeName, ModuleName),
50    [maybe_recover(Q) || Q <- rabbit_amqqueue:list()],
51    ok.
52
53unregister(TypeName) ->
54    rabbit_registry:unregister(queue_decorator, TypeName),
55    [maybe_recover(Q) || Q <- rabbit_amqqueue:list()],
56    ok.
57
58maybe_recover(Q0) when ?is_amqqueue(Q0) ->
59    Name = amqqueue:get_name(Q0),
60    Decs0 = amqqueue:get_decorators(Q0),
61    Q1 = set(Q0),
62    Decs1 = amqqueue:get_decorators(Q1),
63    Old = lists:sort(select(Decs0)),
64    New = lists:sort(select(Decs1)),
65    case New of
66        Old ->
67            ok;
68        _   ->
69            %% TODO LRB JSP 160169569 should startup be passed Q1 here?
70            [M:startup(Q0) || M <- New -- Old],
71            rabbit_amqqueue:update_decorators(Name)
72    end.
73