问题

I have a set of structs defined in Thrift such as the following:

struct Foo {
  1: i32 a,
  2: i64 b
}

I need to do the following in C++:

(a) Serialize instances of Foo into Thrift-compatible bytes (either using the Binary or Compact Thrift protocol)

(b) Send the byte-serialized instances to a Kafka topic

Question

How I do send the Thrift serialized instances to a Kafka cluster?

Thanks in advance

回答1:

Figured out the answer to my own question.

Serialization

The code snippet below illustrates how to serialize an instance of Foo to Thrift-compatible bytes (using the Thrift Compact protocol). In order to use the Binary protocol, replace TCompactProtocol with TBinaryProtocol.

#include <thrift/transport/TBufferTransports.h>
#include <thrift/protocol/TCompactProtocol.h>

using apache::thrift::protocol::TCompactProtocol;
using apache::thrift::transport::TMemoryBuffer;

...
...
boost::shared_ptr<TMemoryBuffer> buffer(new TMemoryBuffer());
boost::shared_ptr<TCompactProtocol> protocol(new TCompactProtocol(buffer));
uint8_t **serialized_bytes = reinterpret_cast<uint8_t **>(malloc(sizeof(uint8_t *)));
uint32_t num_bytes = 0;

// 'foo' is an instance of Foo
foo->write(protocol.get());
buffer->getBuffer(serialized_bytes, &num_bytes);

Sending to Kafka cluster

The following code snippet illustrates how to send the Thrift-compatible bytes to a Kafka cluster.

NOTE: The kafka client library used below is librdkafka.

#include "rdkafkacpp.h"

std::string errstr;

// Create global configuration
RdKafka::Conf *conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
conf->set("metadata.broker.list", "localhost:9092", errstr);
conf->set("api.version.request", "true", errstr);

// Create kafka producer
RdKafka::Producer *producer = RdKafka::Producer::create(conf, errstr);

// Create topic-specific configuration
RdKafka::Topic *topic = RdKafka::Topic::create(producer, "topic_name", nullptr, errstr);

auto partition = 1;

// Sending the serialized bytes to Kafka cluster
auto res = producer->produce(
    topic, partition,
    RdKafka::Producer::RK_MSG_COPY /* Copy payload */,
    serialized_bytes, num_bytes,
    NULL, NULL);

  if (res != RdKafka::ERR_NO_ERROR) {
    std::cerr << "Failed to publish message" << RdKafka::err2str(res) << std::endl;
  } else {
    std::cout << "Published message of " << num_bytes << " bytes" << std::endl;
  }

producer->flush(10000);

来源：https://stackoverflow.com/questions/42871143/serializing-a-serialized-thrift-struct-to-kafka-in-c

标签

c++