++ed by:
AERO SREZIC
Author image 🦖🦜Graham Ollis🦃🦕
and 1 contributors

NAME

Kafka::Librd - bindings for librdkafka

SYNOPSIS

    use Kafka::Librd;

    my $kafka = Kafka::Librd->new(
        Kafka::Librd::RD_KAFKA_CONSUMER,
        {
            "group.id" => 'consumer_id',
        },
    );
    $kafka->brokers_add('server1:9092,server2:9092');
    $kafka->subscribe( \@topics );
    while (1) {
        my $msg = $kafka->consumer_poll(1000);
        if ($msg) {
            if ( $msg->err ) {
                say "Error: ", Kafka::Librd::Error::to_string($err);
            }
            else {
                say $msg->payload;
            }
        }
    }

DESCRIPTION

This module provides perl bindings for librdkafka.

METHODS

new

    $kafka = $class->new($type, \%config)

Create a new instance. $type can be either RD_KAFKA_CONSUMER or RD_KAFKA_PRODUCER. Config is a hash with configuration parameters as described in https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md, additionally it may include default_topic_config key, with a hash containing default topic configuration properties.

brokers_add

    $cnt = $kafka->brokers_add($brokers)

add one or more brokers to the list of initial bootstrap brokers. $brokers is a comma separated list of brokers in the format [proto://]host[:port].

subscribe

    $err = $kafka->subscribe(\@topics)

subscribe to the list of topics using balanced consumer groups.

unsubscribe

    $err = $kafka->unsubscribe

unsubscribe from the current subscription set

subscription

    $tplist = $kafka->subscription

return current subscriptions. Subscription returned as a reference to array of hashes with the following fields: topic, partition, offset, metadata.

assign

    $err = $kafka->assign(\@tplist)

assign partitions to consume. @tplist is an array of hashes with topic and partition fields set.

assignment

    $tplist = $kafka->assignment

return current assignment. Result returned in the same way as for "subscription".

consumer_poll

    $msg = $kafka->consumer_poll($timeout_ms)

poll for messages or events. If any message or event received, returns "Kafka::Librd::Message" object. If <$msg-err>> for returned object is zero (RD_KAFKA_RESP_ERR_NO_ERROR), then it is a proper message, otherwise it is an event or an error.

commit

    $err = $kafka->commit(\@tplist, $async)

commit offsets to the broker. @tplist is an array of hashes with the following keys: topic, partition, offset, metadata. If @topic_partition_list is missing or undef, then current partition assignment is used instead. If $async is 1, then method returns immediately, if it is 0 or missing then method blocks until offsets are committed.

commit_message

    $err = $kafka->commit_message($msg, $async)

commit message's offset for the message's partition. $async same as for "commit".

committed

    $tplist = $kafka->committed(\@tplist, $timeout_ms)

retrieve committed offsets for topics and partitions specified in @tplist, which is an array of hashes with topic and partition fields. Returned $tplist contains a copy of the input list with added offset fields.

position

    $tplist = $kafka->position(\@tplist)

retrieve current offsets for topics and partitions specified in @tplist, which is an array of hashes with topic and partition fields. Returned $tplist contains a copy of the input list with added offset fields.

consumer_close

    $err = $kafka->consumer_close

close down the consumer

topic

    $topic = $kafka->topic($name, \%config)

Return a topic object, that can be used to produce messages.

If an error occurs during creation of the topic, undef is returned. In such case use "Kafka::Librd::Error::last_error" to obtain the corresponding error code!

outq_len

    $len = $kafka->outq_len

return the current out queue length.

flush

    $kafka->flush($timeout_ms)

wait until all outstanding produce requests, et.al, are completed.

destroy

    $kafka->destroy

destroy kafka handle

dump

    $kafka->dump

dump internal state of kafka handle to stdout, only useful for debugging

Kafka::Librd::Topic

This class maps to rd_kafka_topic_t structure from librdkafka and represents topic. It should be created with "topic" method of Kafka::Librd object. It provides the following method:

produce

    $status = $topic->produce($partition, $msgflags, $payload, $key)

produce a message for the topic. $msgflags can be RD_KAFKA_MSG_F_BLOCK in the future, but currently it should be set to 0, RD_KAFKA_MSG_F_COPY and RD_KAFKA_MSG_F_FREE must not be used, internally RD_KAFKA_MSG_F_COPY is always set.

The returned status is -1 in case of an error, otherwise 0. The error code can be retrieved using the "Kafka::Librd::Error::last_error" function.

destroy

    $topic->destroy

destroy topic handle

Kafka::Librd::Message

This class maps to rd_kafka_message_t structure from librdkafka and represents message or event. Objects of this class have the following methods:

err

return error code from the message

topic

return topic name

partition

return partition number

offset

return offset. Note, that the value is truncated to 32 bit if your perl doesn't support 64 bit integers.

key

return message key

payload

return message payload

timestamp(\$tstype)

return message timestamp (milliseconds since UNIX epoch)

The $tstype argument is optional, and if present, it should be a scalar reference. It will be filled with one of the following values:

  • Kafka::Librd::RD_KAFKA_TIMESTAMP_NOT_AVAILABLE

  • Kafka::Librd::RD_KAFKA_TIMESTAMP_CREATE_TIME

  • Kafka::Librd::RD_KAFKA_TIMESTAMP_LOG_APPEND_TIME

Kafka::Librd::Error

Kafka::Librd::Error::to_string

   my $error_message =  Kafka::Librd::Error::to_string($err)

Convert an error code into a human-readable error description. Use this for error codes returned by "Kafka::Librd::Error::last_error" and Kafka::Librd::Message::err.

Kafka::Librd::Error::last_error

    my $err = Kafka::Librd::Error::last_error

Retrieve the last error state set by function calls "topic" and "produce". This function should be called immediately after those functions, since they store error information globally.

CAVEATS

Message offset is truncated to 32 bit if perl compiled without support for 64 bit integers.

SEE ALSO

https://github.com/edenhill/librdkafka

BUGS

Please report any bugs or feature requests via GitHub bug tracker at http://github.com/uperl/Kafka-Librd/issues.

AUTHOR

Original author Pavel Shaydo <zwon at cpan.org>

Current maintainer Graham Ollis <plicease@cpan.org>

LICENSE AND COPYRIGHT

Copyright (C) 2016, 2017 Pavel Shaydo

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.