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%% 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_registry).
-behaviour(gen_server).
-export([start_link/0]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
code_change/3]).
-export([register/3, unregister/2,
binary_to_type/1, lookup_module/2, lookup_all/1]).
-define(SERVER, ?MODULE).
-define(ETS_NAME, ?MODULE).
-spec start_link() -> rabbit_types:ok_pid_or_error().
-spec register(atom(), binary(), atom()) -> 'ok'.
-spec unregister(atom(), binary()) -> 'ok'.
-spec binary_to_type(binary()) -> atom() | rabbit_types:error('not_found').
-spec lookup_module(atom(), atom()) ->
rabbit_types:ok_or_error2(atom(), 'not_found').
-spec lookup_all(atom()) -> [{atom(), atom()}].
%%---------------------------------------------------------------------------
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%%---------------------------------------------------------------------------
register(Class, TypeName, ModuleName) ->
gen_server:call(?SERVER, {register, Class, TypeName, ModuleName}, infinity).
unregister(Class, TypeName) ->
gen_server:call(?SERVER, {unregister, Class, TypeName}, infinity).
%% This is used with user-supplied arguments (e.g., on exchange
%% declare), so we restrict it to existing atoms only. This means it
%% can throw a badarg, indicating that the type cannot have been
%% registered.
binary_to_type(TypeBin) when is_binary(TypeBin) ->
case catch list_to_existing_atom(binary_to_list(TypeBin)) of
{'EXIT', {badarg, _}} -> {error, not_found};
TypeAtom -> TypeAtom
end.
lookup_module(Class, T) when is_atom(T) ->
case ets:lookup(?ETS_NAME, {Class, T}) of
[{_, Module}] ->
{ok, Module};
[] ->
{error, not_found}
end.
lookup_all(Class) ->
[{K, V} || [K, V] <- ets:match(?ETS_NAME, {{Class, '$1'}, '$2'})].
%%---------------------------------------------------------------------------
internal_binary_to_type(TypeBin) when is_binary(TypeBin) ->
list_to_atom(binary_to_list(TypeBin)).
internal_register(Class, TypeName, ModuleName)
when is_atom(Class), is_binary(TypeName), is_atom(ModuleName) ->
ClassModule = class_module(Class),
Type = internal_binary_to_type(TypeName),
RegArg = {{Class, Type}, ModuleName},
ok = sanity_check_module(ClassModule, ModuleName),
true = ets:insert(?ETS_NAME, RegArg),
conditional_register(RegArg),
ok = ClassModule:added_to_rabbit_registry(Type, ModuleName),
ok.
internal_unregister(Class, TypeName) ->
ClassModule = class_module(Class),
Type = internal_binary_to_type(TypeName),
UnregArg = {Class, Type},
conditional_unregister(UnregArg),
true = ets:delete(?ETS_NAME, UnregArg),
ok = ClassModule:removed_from_rabbit_registry(Type),
ok.
%% register exchange decorator route callback only when implemented,
%% in order to avoid unnecessary decorator calls on the fast
%% publishing path
conditional_register({{exchange_decorator, Type}, ModuleName}) ->
case erlang:function_exported(ModuleName, route, 2) of
true -> true = ets:insert(?ETS_NAME,
{{exchange_decorator_route, Type},
ModuleName});
false -> ok
end;
conditional_register(_) ->
ok.
conditional_unregister({exchange_decorator, Type}) ->
true = ets:delete(?ETS_NAME, {exchange_decorator_route, Type}),
ok;
conditional_unregister(_) ->
ok.
sanity_check_module(ClassModule, Module) ->
case catch lists:member(ClassModule,
lists:flatten(
[Bs || {Attr, Bs} <-
Module:module_info(attributes),
Attr =:= behavior orelse
Attr =:= behaviour])) of
{'EXIT', {undef, _}} -> {error, not_module};
false -> {error, {not_type, ClassModule}};
true -> ok
end.
% Registry class modules. There should exist module for each registry class.
% Class module should be behaviour (export behaviour_info/1) and implement
% rabbit_registry_class behaviour itself: export added_to_rabbit_registry/2
% and removed_from_rabbit_registry/1 functions.
class_module(exchange) -> rabbit_exchange_type;
class_module(auth_mechanism) -> rabbit_auth_mechanism;
class_module(runtime_parameter) -> rabbit_runtime_parameter;
class_module(exchange_decorator) -> rabbit_exchange_decorator;
class_module(queue_decorator) -> rabbit_queue_decorator;
class_module(policy_validator) -> rabbit_policy_validator;
class_module(operator_policy_validator) -> rabbit_policy_validator;
class_module(policy_merge_strategy) -> rabbit_policy_merge_strategy;
class_module(ha_mode) -> rabbit_mirror_queue_mode;
class_module(channel_interceptor) -> rabbit_channel_interceptor;
class_module(queue_master_locator) -> rabbit_queue_master_locator.
%%---------------------------------------------------------------------------
init([]) ->
?ETS_NAME = ets:new(?ETS_NAME, [protected, set, named_table]),
{ok, none}.
handle_call({register, Class, TypeName, ModuleName}, _From, State) ->
ok = internal_register(Class, TypeName, ModuleName),
{reply, ok, State};
handle_call({unregister, Class, TypeName}, _From, State) ->
ok = internal_unregister(Class, TypeName),
{reply, ok, State};
handle_call(Request, _From, State) ->
{stop, {unhandled_call, Request}, State}.
handle_cast(Request, State) ->
{stop, {unhandled_cast, Request}, State}.
handle_info(Message, State) ->
{stop, {unhandled_info, Message}, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
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