Go back to reading multi_buy_enabled flag

config/sys.config

@@ -24,6 +24,7 @@
             host => "localhost",
             port => 8080
         }},
+        {multi_buy_enabled, true},
         {multi_buy_service, #{
             transport => http,
             host => "localhost",

config/sys.config.src

@@ -26,6 +26,7 @@
             host => "${HPR_DOWNLINK_SERVICE_HOST}",
             port => "${HPR_DOWNLINK_SERVICE_PORT}"
         }},
+        {multi_buy_enabled, ${HPR_MULTI_BUY_ENABLED}},
         {multi_buy_service, #{
             transport => "${HPR_MULTI_BUY_SERVICE_TRANSPORT}",
             host => "${HPR_MULTI_BUY_SERVICE_HOST}",

src/hpr_multi_buy.erl

@@ -7,7 +7,8 @@
     init/0,
     update_counter/2,
     cleanup/1,
-    make_key/2
+    make_key/2,
+    enabled/0
 ]).
 
 -define(ETS, hpr_multi_buy_ets).
@@ -41,22 +42,28 @@ update_counter(Key, Max) ->
         LocalCounter when LocalCounter > Max ->
             {error, ?MULTIBUY};
         LocalCounter ->
-            case request(Key) of
-                {ok, ServiceCounter} when ServiceCounter > Max ->
-                    ets:update_counter(
-                        ?ETS,
-                        Key,
-                        {2, Max - LocalCounter + 1},
-                        {default, 0, erlang:system_time(millisecond)}
-                    ),
-                    {error, ?MULTIBUY};
-                {ok, _ServiceCounter} ->
+            case enabled() of
+                false ->
+                    %% ETS-only mode: no external service configured
                     {ok, false};
-                {error, Reason} ->
-                    lager:error("failed to get a counter for ~s: ~p", [
-                        hpr_utils:bin_to_hex_string(Key), Reason
-                    ]),
-                    {ok, true}
+                true ->
+                    case request(Key) of
+                        {ok, ServiceCounter} when ServiceCounter > Max ->
+                            ets:update_counter(
+                                ?ETS,
+                                Key,
+                                {2, Max - LocalCounter + 1},
+                                {default, 0, erlang:system_time(millisecond)}
+                            ),
+                            {error, ?MULTIBUY};
+                        {ok, _ServiceCounter} ->
+                            {ok, false};
+                        {error, Reason} ->
+                            lager:error("failed to get a counter for ~s: ~p", [
+                                hpr_utils:bin_to_hex_string(Key), Reason
+                            ]),
+                            {ok, true}
+                    end
             end
     end.
 
@@ -82,6 +89,10 @@ make_key(PacketUp, Route) ->
 %% Internal Function Definitions
 %% ------------------------------------------------------------------
 
+-spec enabled() -> boolean().
+enabled() ->
+    application:get_env(hpr, multi_buy_enabled, true).
+
 -spec scheduled_cleanup(Duration :: non_neg_integer()) -> ok.
 scheduled_cleanup(Duration) ->
     {ok, _} = timer:apply_interval(Duration, ?MODULE, cleanup, [Duration]),
@@ -119,6 +130,7 @@ all_test_() ->
         ?_test(test_max_too_low()),
         ?_test(test_update_counter()),
         ?_test(test_update_counter_with_service()),
+        ?_test(test_update_counter_ets_only()),
         ?_test(test_cleanup()),
         ?_test(test_scheduled_cleanup())
     ]}.
@@ -173,6 +185,29 @@ test_update_counter_with_service() ->
     ?assertEqual({error, ?MULTIBUY}, ?MODULE:update_counter(Key, Max)),
     ok.
 
+test_update_counter_ets_only() ->
+    %% Disable external multi-buy service (ETS-only mode)
+    application:set_env(hpr, multi_buy_enabled, false),
+
+    Key = crypto:strong_rand_bytes(16),
+    Max = 3,
+
+    %% The external service should never be called in ETS-only mode
+    meck:expect(helium_multi_buy_multi_buy_client, inc, fun(_, _) ->
+        error(should_not_be_called)
+    end),
+
+    %% In ETS-only mode, successful updates return {ok, false} (not free)
+    ?assertEqual({ok, false}, ?MODULE:update_counter(Key, Max)),
+    ?assertEqual({ok, false}, ?MODULE:update_counter(Key, Max)),
+    ?assertEqual({ok, false}, ?MODULE:update_counter(Key, Max)),
+    %% Once max is exceeded, still get multi_buy error from local ETS
+    ?assertEqual({error, ?MULTIBUY}, ?MODULE:update_counter(Key, Max)),
+
+    %% Re-enable for other tests
+    application:set_env(hpr, multi_buy_enabled, true),
+    ok.
+
 test_cleanup() ->
     Key1 = crypto:strong_rand_bytes(16),
     Key2 = crypto:strong_rand_bytes(16),

src/hpr_routing.erl

@@ -502,6 +502,9 @@ foreach_setup() ->
     ok = hpr_multi_buy:init(),
     ok = hpr_device_stats:init(),
     ok = hpr_netid_stats:init(),
+    %% NOTE: These tests expect that routing is setup to hit multi-buy, but the
+    %% grpc service is not there.
+    application:set_env(hpr, multi_buy_enabled, true),
     meck:new(hpr_gateway_location, [passthrough]),
     meck:expect(hpr_gateway_location, get, fun(_) -> {error, not_implemented} end),
     ok.

src/hpr_sup.erl

@@ -76,7 +76,7 @@ init([]) ->
     _ = maybe_start_channel(ConfigServiceConfig, ?IOT_CONFIG_CHANNEL),
     _ = maybe_start_channel(LocationServiceConfig, ?LOCATION_CHANNEL),
     _ = maybe_start_channel(DownlinkServiceConfig, ?DOWNLINK_CHANNEL),
-    _ = maybe_start_channel(MultiBuyServiceConfig, ?MULTI_BUY_CHANNEL),
+    _ = maybe_start_multi_buy_channel(MultiBuyServiceConfig),
 
     ElliConfigMetrics = [
         {callback, hpr_metrics_handler},
@@ -132,6 +132,14 @@ maybe_start_channel(Config, ChannelName) ->
             lager:error("no host/port/transport to start ~s", [ChannelName])
     end.
 
+maybe_start_multi_buy_channel(Config) ->
+    case hpr_multi_buy:enabled() of
+        true ->
+            maybe_start_channel(Config, ?MULTI_BUY_CHANNEL);
+        false ->
+            lager:info("multi_buy disabled, not starting ~s", [?MULTI_BUY_CHANNEL])
+    end.
+
 -spec timing(Label :: string(), Fn :: fun()) -> ok.
 timing(Label, Fn) ->
     Start = erlang:system_time(millisecond),