How to check if brokers recovered from all down?

[BewareMyPower]

Read the FAQ first: https://github.com/edenhill/librdkafka/wiki/FAQ

Description

I'm maintaining a C++ kafka client sdk that wraps librdkafka, and it used rd_kafka_broker_any() (in rdkafka_broker.c) to check if there is any up broker.

Though it's an internal function, it's not a static function, so the sdk explicitly declared this function to call it.

I thought it's not a proper way, so I want to

• use error_cb to check if brokers are all down by checking ERR__ALL_BROKERS_DOWN;
• use stats_cb to parse json to find if exists some broker that broker[].state == UP.

Just like #1801.

But the previous maintainer thought it's too complicated to define a callback, parse json or just do some string operations in stats_cb, etc. And it seems not better than just call rd_kafka_broker_any(), except that rd_kafka_broker_destroy() (which is another internal function or macro) must be called to reduce refcnt.

Is there a simpler way to check if brokers recovered from all down ?

Additional, is there any needs to call rd_kafka_produce() to send message to the produce queue in dr_msg_cb when err == RD_KAFKA_ERR__MSG_TIMED_OUT? And if there is other error like ERR_LEADER_NOT_AVAILABLE in dr_msg_cb, and I call rd_kafka_produce() to enqueue the message again, will repeated message produced happen?

Appreciate you response and help.

Checklist

IMPORTANT: We will close issues where the checklist has not been completed.

Please provide the following information:

• librdkafka version (release number or git tag): 1.0.1
• Apache Kafka version: 1.1.0
• librdkafka client configuration: <REPLACE with e.g., message.timeout.ms=123, auto.reset.offset=earliest, ..>
• Operating system: <REPLACE with e.g., Centos 5 (x64)>
• Provide logs (with debug=.. as necessary) from librdkafka
• Provide broker log excerpts
• Critical issue

[DavidLiuXh]

@edenhill
Please help me to see this question. Thanks~

[edenhill]

There's no support for calling librdkafka-internal functions, don't do it.