#include <userver/kafka/producer.hpp>

Detailed Description

Apache Kafka Producer Client.

It exposes the API to send an arbitrary message to the Kafka Broker to certain topic by given key and optional partition.

Important implementation details

Implementation does not block on any send to Kafka and asynchronously waits for each message to be delivered.

Producer periodically polls the metadata about delivered messages from Kafka Broker, blocking for some time, in separate task processor.

Producer maintains the per topic statistics including the broker connection errors.

Remarks: Destructor may block for no more than a couple of seconds to ensure all sent messages are properly delivered

See also: https://docs.confluent.io/platform/current/clients/producer.html

Definition at line 44 of file producer.hpp.

Public Member Functions
	Producer (std::unique_ptr< impl::Configuration > configuration, engine::TaskProcessor &producer_task_processor, std::chrono::milliseconds poll_timeout, std::size_t send_retries)
	Creates the Kafka Producer.

	~Producer ()
	Waits until all messages are sent for a certain timeout and destroy the inner producer.

	Producer (const Producer &)=delete

	Producer (Producer &&)=delete

Producer &	operator= (const Producer &)=delete

Producer &	operator= (Producer &&)=delete

void	Send (const std::string &topic_name, std::string_view key, std::string_view message, std::optional< std::uint32_t > partition=std::nullopt) const
	Sends given message to topic `topic_name` by given `key` and `partition` (if passed) with payload contains the `message` data. Asynchronously waits until the message is delivered or the delivery error occured.

engine::TaskWithResult< void >	SendAsync (std::string topic_name, std::string key, std::string message, std::optional< std::uint32_t > partition=std::nullopt) const
	Same as `Producer::Send`, but returns the task which can be used to wait the message delivery.

void	DumpMetric (utils::statistics::Writer &writer) const
	Dumps per topic messages produce statistics.

Static Public Attributes
static constexpr std::chrono::milliseconds	kDefaultPollTimeout {10}
	Time producer waits for new delivery events.

static constexpr std::size_t	kDefaultSendRetries = 5
	How many times `Produce::Send*` retries when delivery failures. Retries take place only when errors are transient.

Member Function Documentation

◆ DumpMetric()

void kafka::Producer::DumpMetric ( utils::statistics::Writer & writer ) const

Dumps per topic messages produce statistics.

See also: impl/stats.hpp

◆ Send()

void kafka::Producer::Send	(	const std::string &	topic_name,
		std::string_view	key,
		std::string_view	message,
		std::optional< std::uint32_t >	partition = std::nullopt ) const

Sends given message to topic topic_name by given key and partition (if passed) with payload contains the message data. Asynchronously waits until the message is delivered or the delivery error occured.

No payload data is copied. Method holds the data until message is delivered.

thread-safe and can be called from any number of threads simultaneously.

Producer::Send call may take at most delivery_timeout_ms x send_retries_count milliseconds.

If partition not passed, partition is chosen by internal Kafka partitioner.

Warning: if enable_idempotence option is enabled, do not use both explicit partitions and Kafka-chosen ones

Exceptions

std::runtime_error if message is not delivery and acked by Kafka Broker

◆ SendAsync()

engine::TaskWithResult< void > kafka::Producer::SendAsync	(	std::string	topic_name,
		std::string	key,
		std::string	message,
		std::optional< std::uint32_t >	partition = std::nullopt ) const

Same as Producer::Send, but returns the task which can be used to wait the message delivery.

Warning: If user schedules a batch of send requests with Producer::SendAsync, some send requests may be retried by the library (for instance, in case of network blink). Though, the order messages are written to partition may differ from the order messages are initially sent

Member Data Documentation

◆ kDefaultPollTimeout

constexpr std::chrono::milliseconds kafka::Producer::kDefaultPollTimeout {10}

staticconstexpr

Time producer waits for new delivery events.

Definition at line 47 of file producer.hpp.

◆ kDefaultSendRetries

constexpr std::size_t kafka::Producer::kDefaultSendRetries = 5

staticconstexpr

How many times Produce::Send* retries when delivery failures. Retries take place only when errors are transient.

Remarks: librdkafka already has a retry mechanism. Moreover, user-retried requests may lead to messages reordering or duplication. Nevertheless, the library retries a small list of delivery errors (such as message guaranteed timeouts), including errors those are not retried by librdkafka and errors that may occure when the Kafka cluster or topic have just been created (for instance, in tests)

See also: impl/producer_impl.cpp for the list of errors retryable by library

Definition at line 59 of file producer.hpp.

The documentation for this class was generated from the following file:

userver/kafka/producer.hpp