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rdkafka_consume_batch.cpp
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rdkafka_consume_batch.cpp
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/*
* librdkafka - Apache Kafka C library
*
* Copyright (c) 2018, Magnus Edenhill
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Apache Kafka consumer & producer example programs
* using the Kafka driver from librdkafka
* (https://github.com/edenhill/librdkafka)
*
* This example shows how to read batches of messages.
* Note that messages are fetched from the broker in batches regardless
* of how the application polls messages from librdkafka, this example
* merely shows how to accumulate a set of messages in the application.
*/
#include <iostream>
#include <string>
#include <cstdlib>
#include <cstdio>
#include <csignal>
#include <cstring>
#ifndef _MSC_VER
#include <sys/time.h>
#endif
#ifdef _MSC_VER
#include "../win32/wingetopt.h"
#include <atltime.h>
#elif _AIX
#include <unistd.h>
#else
#include <getopt.h>
#include <unistd.h>
#endif
/*
* Typically include path in a real application would be
* #include <librdkafka/rdkafkacpp.h>
*/
#include "rdkafkacpp.h"
static bool run = true;
static void sigterm (int sig) {
run = false;
}
/**
* @returns the current wall-clock time in milliseconds
*/
static int64_t now () {
#ifndef _MSC_VER
struct timeval tv;
gettimeofday(&tv, NULL);
return ((int64_t)tv.tv_sec * 1000) + (tv.tv_usec / 1000);
#else
#error "now() not implemented for Windows, please submit a PR"
#endif
}
/**
* @brief Accumulate a batch of \p batch_size messages, but wait
* no longer than \p batch_tmout milliseconds.
*/
static std::vector<RdKafka::Message *>
consume_batch (RdKafka::KafkaConsumer *consumer, size_t batch_size, int batch_tmout) {
std::vector<RdKafka::Message *> msgs;
msgs.reserve(batch_size);
int64_t end = now() + batch_tmout;
int remaining_timeout = batch_tmout;
while (msgs.size() < batch_size) {
RdKafka::Message *msg = consumer->consume(remaining_timeout);
switch (msg->err()) {
case RdKafka::ERR__TIMED_OUT:
delete msg;
return msgs;
case RdKafka::ERR_NO_ERROR:
msgs.push_back(msg);
break;
default:
std::cerr << "%% Consumer error: " << msg->errstr() << std::endl;
run = false;
delete msg;
return msgs;
}
remaining_timeout = end - now();
if (remaining_timeout < 0)
break;
}
return msgs;
}
int main (int argc, char **argv) {
std::string errstr;
std::string topic_str;
std::vector<std::string> topics;
int batch_size = 100;
int batch_tmout = 1000;
/* Create configuration objects */
RdKafka::Conf *conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
if (conf->set("enable.partition.eof", "false", errstr) != RdKafka::Conf::CONF_OK) {
std::cerr << errstr << std::endl;
exit(1);
}
/* Read command line arguments */
int opt;
while ((opt = getopt(argc, argv, "g:B:T::b:X:")) != -1) {
switch (opt) {
case 'g':
if (conf->set("group.id", optarg, errstr) != RdKafka::Conf::CONF_OK) {
std::cerr << errstr << std::endl;
exit(1);
}
break;
case 'B':
batch_size = atoi(optarg);
break;
case 'T':
batch_tmout = atoi(optarg);
break;
case 'b':
if (conf->set("bootstrap.servers", optarg, errstr) != RdKafka::Conf::CONF_OK) {
std::cerr << errstr << std::endl;
exit(1);
}
break;
case 'X':
{
char *name, *val;
name = optarg;
if (!(val = strchr(name, '='))) {
std::cerr << "%% Expected -X property=value, not " <<
name << std::endl;
exit(1);
}
*val = '\0';
val++;
if (conf->set(name, val, errstr) != RdKafka::Conf::CONF_OK) {
std::cerr << errstr << std::endl;
exit(1);
}
}
break;
default:
goto usage;
}
}
/* Topics to consume */
for (; optind < argc ; optind++)
topics.push_back(std::string(argv[optind]));
if (topics.empty() || optind != argc) {
usage:
fprintf(stderr,
"Usage: %s -g <group-id> -B <batch-size> [options] topic1 topic2..\n"
"\n"
"librdkafka version %s (0x%08x)\n"
"\n"
" Options:\n"
" -g <group-id> Consumer group id\n"
" -B <batch-size> How many messages to batch (default: 100).\n"
" -T <batch-tmout> How long to wait for batch-size to accumulate in milliseconds. (default 1000 ms)\n"
" -b <brokers> Broker address (localhost:9092)\n"
" -X <prop=name> Set arbitrary librdkafka configuration property\n"
"\n",
argv[0],
RdKafka::version_str().c_str(), RdKafka::version());
exit(1);
}
signal(SIGINT, sigterm);
signal(SIGTERM, sigterm);
/* Create consumer */
RdKafka::KafkaConsumer *consumer = RdKafka::KafkaConsumer::create(conf, errstr);
if (!consumer) {
std::cerr << "Failed to create consumer: " << errstr << std::endl;
exit(1);
}
delete conf;
/* Subscribe to topics */
RdKafka::ErrorCode err = consumer->subscribe(topics);
if (err) {
std::cerr << "Failed to subscribe to " << topics.size() << " topics: "
<< RdKafka::err2str(err) << std::endl;
exit(1);
}
/* Consume messages in batches of \p batch_size */
while (run) {
auto msgs = consume_batch(consumer, batch_size, batch_tmout);
std::cout << "Accumulated " << msgs.size() << " messages:" << std::endl;
for (auto &msg : msgs) {
std::cout << " Message in " << msg->topic_name() << " [" << msg->partition() << "] at offset " << msg->offset() << std::endl;
delete msg;
}
}
/* Close and destroy consumer */
consumer->close();
delete consumer;
return 0;
}