Added a simple producer example

examples/.gitignore

@@ -4,4 +4,4 @@ rdkafka_example_cpp
 rdkafka_consumer_example
 rdkafka_consumer_example_cpp
 kafkatest_verifiable_client
-
+rdkafka_simple_producer

examples/Makefile

@@ -1,6 +1,6 @@
 EXAMPLES ?= rdkafka_example rdkafka_performance rdkafka_example_cpp \
 	rdkafka_consumer_example rdkafka_consumer_example_cpp \
-	kafkatest_verifiable_client
+	kafkatest_verifiable_client rdkafka_simple_producer
 
 all: $(EXAMPLES)
 
@@ -28,6 +28,10 @@ rdkafka_example: ../src/librdkafka.a rdkafka_example.c
 	@echo "# More usage options:"
 	@echo "./$@ -h"
 
+rdkafka_simple_producer: ../src/librdkafka.a rdkafka_simple_producer.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) $@.c -o $@ $(LDFLAGS) \
+		../src/librdkafka.a $(LIBS)
+
 rdkafka_consumer_example: ../src/librdkafka.a rdkafka_consumer_example.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) rdkafka_consumer_example.c -o $@ $(LDFLAGS) \
 		../src/librdkafka.a $(LIBS)

examples/rdkafka_simple_producer.c

@@ -0,0 +1,260 @@
+/*
+ * librdkafka - Apache Kafka C library
+ *
+ * Copyright (c) 2017, 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.
+ */
+
+/**
+ * Simple Apache Kafka producer
+ * using the Kafka driver from librdkafka
+ * (https://github.com/edenhill/librdkafka)
+ */
+
+#include <stdio.h>
+#include <signal.h>
+#include <string.h>
+
+
+/* Typical include path would be <librdkafka/rdkafka.h>, but this program
+ * is builtin from within the librdkafka source tree and thus differs. */
+#include "rdkafka.h"
+
+
+static int run = 1;
+
+/**
+ * @brief Signal termination of program
+ */
+static void stop (int sig) {
+        run = 0;
+        fclose(stdin); /* abort fgets() */
+}
+
+
+/**
+ * @brief Message delivery report callback.
+ *
+ * This callback is called exactly once per message, indicating if
+ * the message was succesfully delivered
+ * (rkmessage->err == RD_KAFKA_RESP_ERR_NO_ERROR) or permanently
+ * failed delivery (rkmessage->err != RD_KAFKA_RESP_ERR_NO_ERROR).
+ *
+ * The callback is triggered from rd_kafka_poll() and executes on
+ * the application's thread.
+ */
+static void dr_msg_cb (rd_kafka_t *rk,
+                       const rd_kafka_message_t *rkmessage, void *opaque) {
+        if (rkmessage->err)
+                fprintf(stderr, "%% Message delivery failed: %s\n",
+                        rd_kafka_err2str(rkmessage->err));
+        else
+                fprintf(stderr,
+                        "%% Message delivered (%zd bytes, "
+                        "partition %"PRId32")\n",
+                        rkmessage->len, rkmessage->partition);
+
+        /* The rkmessage is destroyed automatically by librdkafka */
+}
+
+
+
+int main (int argc, char **argv) {
+        rd_kafka_t *rk;         /* Producer instance handle */
+        rd_kafka_topic_t *rkt;  /* Topic object */
+        rd_kafka_conf_t *conf;  /* Temporary configuration object */
+        char errstr[512];       /* librdkafka API error reporting buffer */
+        char buf[512];          /* Message value temporary buffer */
+        const char *brokers;    /* Argument: broker list */
+        const char *topic;      /* Argument: topic to produce to */
+
+        /*
+         * Argument validation
+         */
+        if (argc != 3) {
+                fprintf(stderr, "%% Usage: %s <broker> <topic>\n", argv[0]);
+                return 1;
+        }
+
+        brokers = argv[1];
+        topic   = argv[2];
+
+
+        /*
+         * Create Kafka client configuration place-holder
+         */
+        conf = rd_kafka_conf_new();
+
+        /* Set bootstrap broker(s) as a comma-separated list of
+         * host or host:port (default port 9092).
+         * librdkafka will use the bootstrap brokers to acquire the full
+         * set of brokers from the cluster. */
+        if (rd_kafka_conf_set(conf, "bootstrap.servers", brokers,
+                              errstr, sizeof(errstr)) != RD_KAFKA_CONF_OK) {
+                fprintf(stderr, "%s\n", errstr);
+                return 1;
+        }
+
+        /* Set the delivery report callback.
+         * This callback will be called once per message to inform
+         * the application if delivery succeeded or failed.
+         * See dr_msg_cb() above. */
+        rd_kafka_conf_set_dr_msg_cb(conf, dr_msg_cb);
+
+
+        /*
+         * Create producer instance.
+         *
+         * NOTE: rd_kafka_new() takes ownership of the conf object
+         *       and the application must not reference it again after
+         *       this call.
+         */
+        rk = rd_kafka_new(RD_KAFKA_PRODUCER, conf, errstr, sizeof(errstr));
+        if (!rk) {
+                fprintf(stderr,
+                        "%% Failed to create new producer: %s\n", errstr);
+                return 1;
+        }
+
+
+        /* Create topic object that will be reused for each message
+         * produced.
+         *
+         * Both the producer instance (rd_kafka_t) and topic objects (topic_t)
+         * are long-lived objects that should be reused as much as possible.
+         */
+        rkt = rd_kafka_topic_new(rk, topic, NULL);
+        if (!rkt) {
+                fprintf(stderr, "%% Failed to create topic object: %s\n",
+                        rd_kafka_err2str(rd_kafka_last_error()));
+                rd_kafka_destroy(rk);
+                return 1;
+        }
+
+        /* Signal handler for clean shutdown */
+        signal(SIGINT, stop);
+
+        fprintf(stderr,
+                "%% Type some text and hit enter to produce message\n"
+                "%% Or just hit enter to only serve delivery reports\n"
+                "%% Press Ctrl-C or Ctrl-D to exit\n");
+
+        while (run && fgets(buf, sizeof(buf), stdin)) {
+                size_t len = strlen(buf);
+
+                if (buf[len-1] == '\n') /* Remove newline */
+                        buf[--len] = '\0';
+
+                if (len == 0) {
+                        /* Empty line: only serve delivery reports */
+                        rd_kafka_poll(rk, 0/*non-blocking */);
+                        continue;
+                }
+
+                /*
+                 * Send/Produce message.
+                 * This is an asynchronous call, on success it will only
+                 * enqueue the message on the internal producer queue.
+                 * The actual delivery attempts to the broker are handled
+                 * by background threads.
+                 * The previously registered delivery report callback
+                 * (dr_msg_cb) is used to signal back to the application
+                 * when the message has been delivered (or failed).
+                 */
+        retry:
+                if (rd_kafka_produce(
+                            /* Topic object */
+                            rkt,
+                            /* Use builtin partitioner to select partition*/
+                            RD_KAFKA_PARTITION_UA,
+                            /* Make a copy of the payload. */
+                            RD_KAFKA_MSG_F_COPY,
+                            /* Message payload (value) and length */
+                            buf, len,
+                            /* Optional key and its length */
+                            NULL, 0,
+                            /* Message opaque, provided in
+                             * delivery report callback as
+                             * msg_opaque. */
+                            NULL) == -1) {
+                        /**
+                         * Failed to *enqueue* message for producing.
+                         */
+                        fprintf(stderr,
+                                "%% Failed to produce to topic %s: %s\n",
+                                rd_kafka_topic_name(rkt),
+                                rd_kafka_err2str(rd_kafka_last_error()));
+
+                        /* Poll to handle delivery reports */
+                        if (rd_kafka_last_error() ==
+                            RD_KAFKA_RESP_ERR__QUEUE_FULL) {
+                                /* If the internal queue is full, wait for
+                                 * messages to be delivered and then retry.
+                                 * The internal queue represents both
+                                 * messages to be sent and messages that have
+                                 * been sent or failed, awaiting their
+                                 * delivery report callback to be called.
+                                 *
+                                 * The internal queue is limited by the
+                                 * configuration property
+                                 * queue.buffering.max.messages */
+                                rd_kafka_poll(rk, 1000/*block for max 1000ms*/);
+                                goto retry;
+                        }
+                } else {
+                        fprintf(stderr, "%% Enqueued message (%zd bytes) "
+                                "for topic %s\n",
+                                len, rd_kafka_topic_name(rkt));
+                }
+
+
+                /* A producer application should continually serve
+                 * the delivery report queue by calling rd_kafka_poll()
+                 * at frequent intervals.
+                 * Either put the poll call in your main loop, or in a
+                 * dedicated thread, or call it after every
+                 * rd_kafka_produce() call.
+                 * Just make sure that rd_kafka_poll() is still called
+                 * during periods where you are not producing any messages
+                 * to make sure previously produced messages have their
+                 * delivery report callback served (and any other callbacks
+                 * you register). */
+                rd_kafka_poll(rk, 0/*non-blocking*/);
+        }
+
+
+        /* Wait for final messages to be delivered or fail.
+         * rd_kafka_flush() is an abstraction over rd_kafka_poll() which
+         * waits for all messages to be delivered. */
+        fprintf(stderr, "%% Flushing final messages..\n");
+        rd_kafka_flush(rk, 10*1000 /* wait for max 10 seconds */);
+
+        /* Destroy topic object */
+        rd_kafka_topic_destroy(rkt);
+
+        /* Destroy the producer instance */
+        rd_kafka_destroy(rk);
+
+        return 0;
+}