Added support for unknown_topic_cache_ttl option in brod_client

src/brod.erl

@@ -374,6 +374,10 @@ start_client(BootstrapEndpoints, ClientId) ->
 %%     Producer configuration to use when auto_start_producers is true.
 %%     See {@link brod_producer:start_link/4} for details about producer config</li>
 %%
+%%   <li>`unknown_topic_cache_ttl' (optional, default=120000)
+%%
+%%     For how long unknown_topic error will be cached, in ms.</li>
+%%
 %% </ul>
 %%
 %% Connection options can be added to the same proplist. See
@@ -510,7 +514,7 @@ start_consumer(Client, TopicName, ConsumerConfig) ->
 %% is not statically configured for them.
 %% It is up to the callers how they want to distribute their data
 %% (e.g. random, roundrobin or consistent-hashing) to the partitions.
-%% NOTE: The partitions count is cached for 120 seconds.
+%% NOTE: The partitions count is cached.
 -spec get_partitions_count(client(), topic()) ->
         {ok, pos_integer()} | {error, any()}.
 get_partitions_count(Client, Topic) ->

src/brod_client.erl

@@ -71,6 +71,7 @@
 
 -define(DEFAULT_RECONNECT_COOL_DOWN_SECONDS, 1).
 -define(DEFAULT_GET_METADATA_TIMEOUT_SECONDS, 5).
+-define(DEFAULT_UNKNOWN_TOPIC_CACHE_TTL, 120000).
 
 %% ClientId as ets table name.
 -define(ETS(ClientId), ClientId).
@@ -85,8 +86,6 @@
 -define(CONSUMER(Topic, Partition, Pid),
         {?CONSUMER_KEY(Topic, Partition), Pid}).
 
--define(UNKNOWN_TOPIC_CACHE_EXPIRE_SECONDS, 120).
-
 -type endpoint() :: brod:endpoint().
 -type client() :: brod:client().
 -type client_id() :: brod:client_id().
@@ -613,6 +612,7 @@ do_get_metadata(Topic, State) when not is_tuple(Topic) ->
 do_get_metadata(FetchMetdataFor, Topic,
                 #state{ client_id   = ClientId
                       , workers_tab = Ets
+                      , config = Config
                       } = State0) ->
   Topics = case FetchMetdataFor of
              all -> all; %% in case no topic is given, get all
@@ -624,8 +624,11 @@ do_get_metadata(FetchMetdataFor, Topic,
   case request_sync(State, Request) of
     {ok, #kpro_rsp{api = metadata, msg = Metadata}} ->
       TopicMetadataArray = kf(topics, Metadata),
-      ok = update_partitions_count_cache(Ets, TopicMetadataArray),
-      ok = maybe_cache_unknown_topic_partition(Ets, Topic, TopicMetadataArray),
+      UnknownTopicCacheTtl = config(unknown_topic_cache_ttl, Config,
+                                    ?DEFAULT_UNKNOWN_TOPIC_CACHE_TTL),
+      ok = update_partitions_count_cache(Ets, TopicMetadataArray, UnknownTopicCacheTtl),
+      ok = maybe_cache_unknown_topic_partition(Ets, Topic, TopicMetadataArray,
+                                               UnknownTopicCacheTtl),
       {{ok, Metadata}, State};
     {error, Reason} ->
       ?BROD_LOG_ERROR("~p failed to fetch metadata for topics: ~p\n"
@@ -819,29 +822,30 @@ is_cooled_down(Ts, #state{config = Config}) ->
 
 %% call this function after fetched metadata for all topics
 %% to cache the not-found status of a given topic
-maybe_cache_unknown_topic_partition(Ets, Topic, TopicMetadataArray) ->
+maybe_cache_unknown_topic_partition(Ets, Topic, TopicMetadataArray, UnknownTopicCacheTtl) ->
   case find_partition_count_in_topic_metadata_array(TopicMetadataArray, Topic) of
     {error, unknown_topic_or_partition} = Err ->
-      _ = ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Err, os:timestamp()}),
+      _ = ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Err,
+                     {expire, expire_ts(UnknownTopicCacheTtl)}}),
       ok;
     _ ->
       %% do nothing when ok or any other error
       ok
   end.
 
--spec update_partitions_count_cache(ets:tab(), [kpro:struct()]) -> ok.
-update_partitions_count_cache(_Ets, []) -> ok;
-update_partitions_count_cache(Ets, [TopicMetadata | Rest]) ->
+-spec update_partitions_count_cache(ets:tab(), [kpro:struct()], non_neg_integer()) -> ok.
+update_partitions_count_cache(_Ets, [], _UnknownTopicCacheTtl) -> ok;
+update_partitions_count_cache(Ets, [TopicMetadata | Rest], UnknownTopicCacheTtl) ->
   Topic = kf(name, TopicMetadata),
   case get_partitions_count_in_metadata(TopicMetadata) of
     {ok, Cnt} ->
-      ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Cnt, os:timestamp()});
+      ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Cnt, {added, now_ts()}});
     {error, ?unknown_topic_or_partition} = Err ->
-      ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Err, os:timestamp()});
+      ets:insert(Ets, {?TOPIC_METADATA_KEY(Topic), Err, {expire, expire_ts(UnknownTopicCacheTtl)}});
     {error, _Reason} ->
       ok
   end,
-  update_partitions_count_cache(Ets, Rest).
+  update_partitions_count_cache(Ets, Rest, UnknownTopicCacheTtl).
 
 %% Get partition counter from cache.
 %% If cache is not hit, send meta data request to retrieve.
@@ -893,9 +897,8 @@ lookup_partitions_count_cache(Ets, Topic) ->
   try ets:lookup(Ets, ?TOPIC_METADATA_KEY(Topic)) of
     [{_, Count, _Ts}] when is_integer(Count) ->
       {ok, Count};
-    [{_, {error, Reason}, Ts}] ->
-      case timer:now_diff(os:timestamp(), Ts) =<
-            ?UNKNOWN_TOPIC_CACHE_EXPIRE_SECONDS * 1000000 of
+    [{_, {error, Reason}, {expire, ExpireTs}}] when is_integer(ExpireTs) ->
+      case is_expired(ExpireTs) of
         true  -> {error, Reason};
         false -> false
       end;
@@ -987,6 +990,15 @@ safe_gen_call(Server, Call, Timeout) ->
 -spec kf(kpro:field_name(), kpro:struct()) -> kpro:field_value().
 kf(FieldName, Struct) -> kpro:find(FieldName, Struct).
 
+-spec expire_ts(integer()) -> integer().
+expire_ts(Ttl) -> now_ts() + Ttl.
+
+-spec is_expired(integer()) -> boolean().
+is_expired(ExpireTs) -> now_ts() - ExpireTs < 0.
+
+-spec now_ts() -> integer().
+now_ts() -> erlang:monotonic_time(millisecond).
+
 %%%_* Emacs ====================================================================
 %%% Local Variables:
 %%% allout-layout: t

test/brod_client_SUITE.erl

@@ -43,6 +43,7 @@
         , t_sasl_plain_file_ssl/1
         , t_sasl_callback/1
         , t_magic_version/1
+        , t_get_partitions_count_configure_cache_ttl/1
         , t_get_partitions_count_safe/1
         , t_double_stop_consumer/1
         ]).
@@ -125,6 +126,22 @@ t_get_partitions_count_safe(Config) when is_list(Config) ->
   ?assertMatch({error, unknown_topic_or_partition}, Res2),
   ok = brod:stop_client(Client).
 
+
+t_get_partitions_count_configure_cache_ttl(Config) when is_list(Config) ->
+  Client = ?FUNCTION_NAME,
+  ClientConfig = [{unknown_topic_cache_ttl, 100}],
+  ok = start_client(?HOSTS, Client, ClientConfig),
+  Topic = <<"unknown-topic-001">>,
+  Res = brod:get_partitions_count_safe(Client, Topic),
+  ?assertMatch({error, unknown_topic_or_partition}, Res),
+  Res2 = brod_client:lookup_partitions_count_cache(Client, Topic),
+  ?assertMatch({error, unknown_topic_or_partition}, Res2),
+  timer:sleep(101),
+  Res3 = brod_client:lookup_partitions_count_cache(Client, Topic),
+  ?assertMatch(false, Res3),
+  ok = brod:stop_client(Client).
+
+
 t_skip_unreachable_endpoint(Config) when is_list(Config) ->
   Client = t_skip_unreachable_endpoint,
   ok = start_client([{"localhost", 8192} | ?HOSTS], Client),