Elect leaders api implemented

examples/.gitignore

@@ -21,4 +21,5 @@ list_consumer_group_offsets
 alter_consumer_group_offsets
 incremental_alter_configs
 user_scram
-list_offsets
+list_offsets
+elect_leaders

examples/CMakeLists.txt

@@ -62,6 +62,9 @@ target_link_libraries(describe_cluster PUBLIC rdkafka)
 add_executable(list_offsets list_offsets.c ${win32_sources})
 target_link_libraries(list_offsets PUBLIC rdkafka)
 
+add_executable(elect_leaders elect_leaders.c ${win32_sources})
+target_link_libraries(elect_leaders PUBLIC rdkafka)
+
 # The targets below has Unix include dirs and do not compile on Windows.
 if(NOT WIN32)
     add_executable(rdkafka_example rdkafka_example.c)

examples/Makefile

@@ -13,6 +13,7 @@ EXAMPLES ?= rdkafka_example rdkafka_performance rdkafka_example_cpp \
 	incremental_alter_configs \
 	user_scram \
 	list_offsets \
+	elect_leaders \
 	misc
 
 all: $(EXAMPLES)
@@ -153,6 +154,10 @@ list_offsets: ../src/librdkafka.a list_offsets.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) [email protected] -o $@ $(LDFLAGS) \
 		../src/librdkafka.a $(LIBS)
 
+elect_leaders: ../src/librdkafka.a elect_leaders.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) [email protected] -o $@ $(LDFLAGS) \
+		../src/librdkafka.a $(LIBS)
+
 misc: ../src/librdkafka.a misc.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) [email protected] -o $@ $(LDFLAGS) \
 		../src/librdkafka.a $(LIBS)

examples/elect_leaders.c

@@ -0,0 +1,329 @@
+/*
+ * librdkafka - Apache Kafka C library
+ *
+ * Copyright (c) 2024, Confluent Inc.
+ * 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 SH 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.
+ */
+
+/**
+ * Example utility that shows how to use Elect Leaders (AdminAPI)
+ * to trigger preffered or unclean elections for
+ * one or more topic partitions.
+ */
+
+#include <signal.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+
+#ifdef _WIN32
+#include "../win32/wingetopt.h"
+#else
+#include <getopt.h>
+#endif
+
+
+/* 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"
+
+
+const char *argv0;
+
+static rd_kafka_queue_t *queue = NULL; /** Admin result queue.
+                                        *  This is a global so we can
+                                        *  yield in stop() */
+static volatile sig_atomic_t run = 1;
+
+/**
+ * @brief Signal termination of program
+ */
+static void stop(int sig) {
+        if (!run) {
+                fprintf(stderr, "%% Forced termination\n");
+                exit(2);
+        }
+        run = 0;
+        if (queue)
+                rd_kafka_queue_yield(queue);
+}
+
+static void usage(const char *reason, ...) {
+
+        fprintf(stderr,
+                "Elect Leaders usage examples\n"
+                "\n"
+                "Usage: %s <options> <election_type( 0(Preffered)/ 1(Unclean))> "
+                "<topic1> <partition1> ...\n"
+                "\n"
+                "Options:\n"
+                "   -b <brokers>    Bootstrap server list to connect to.\n"
+                "   -X <prop=val>   Set librdkafka configuration property.\n"
+                "                   See CONFIGURATION.md for full list.\n"
+                "   -d <dbg,..>     Enable librdkafka debugging (%s).\n"
+                "\n",
+                argv0, rd_kafka_get_debug_contexts());
+
+        if (reason) {
+                va_list ap;
+                char reasonbuf[512];
+
+                va_start(ap, reason);
+                vsnprintf(reasonbuf, sizeof(reasonbuf), reason, ap);
+                va_end(ap);
+
+                fprintf(stderr, "ERROR: %s\n", reasonbuf);
+        }
+
+        exit(reason ? 1 : 0);
+}
+
+
+#define fatal(...)                                                             \
+        do {                                                                   \
+                fprintf(stderr, "ERROR: ");                                    \
+                fprintf(stderr, __VA_ARGS__);                                  \
+                fprintf(stderr, "\n");                                         \
+                exit(2);                                                       \
+        } while (0)
+
+
+/**
+ * @brief Set config property. Exit on failure.
+ */
+static void conf_set(rd_kafka_conf_t *conf, const char *name, const char *val) {
+        char errstr[512];
+
+        if (rd_kafka_conf_set(conf, name, val, errstr, sizeof(errstr)) !=
+            RD_KAFKA_CONF_OK)
+                fatal("Failed to set %s=%s: %s", name, val, errstr);
+}
+
+static int print_elect_leader_result(const rd_kafka_ElectLeader_result_t *result) {
+        rd_kafka_resp_err_t err;
+        const rd_kafka_topic_partition_result_t **results;
+        size_t results_cnt;
+        size_t i;
+        int retval = 0;
+
+        err = rd_kafka_ElectionResult_error(result);
+
+        results = rd_kafka_ElectionResult_partition(result, &results_cnt);
+
+        if(err){
+                printf("%% ElectLeader failed: %s\n", rd_kafka_err2str(err));
+                retval = 1;
+        } else {
+                for(i = 0; i < results_cnt; i++){
+                        if(rd_kafka_topic_partition_result_error(results[i])){
+                             printf("%% ElectLeader failed for %s [%" PRId32 "] : %s\n",
+                                rd_kafka_topic_partition_result_topic(results[i]),
+                                rd_kafka_topic_partition_result_partition(results[i]),
+                                rd_kafka_topic_partition_result_error_string(results[i]));
+                        }
+                        else{
+                                printf("%% ElectLeader succeeded for %s [%" PRId32 "]\n",
+                                        rd_kafka_topic_partition_result_topic(results[i]),
+                                        rd_kafka_topic_partition_result_partition(results[i]));
+                        }
+                }
+        }
+
+        return retval;
+}
+
+/**
+ * @brief Parse an integer or fail.
+ */
+int64_t parse_int(const char *what, const char *str) {
+        char *end;
+        unsigned long n = strtoull(str, &end, 0);
+
+        if (end != str + strlen(str)) {
+                fprintf(stderr, "%% Invalid input for %s: %s: not an integer\n",
+                        what, str);
+                exit(1);
+        }
+
+        return (int64_t)n;
+}
+
+static void cmd_elect_leader(rd_kafka_conf_t *conf, int argc, char **argv) {
+        rd_kafka_t *rk;
+        char errstr[512];
+        rd_kafka_AdminOptions_t *options;
+        rd_kafka_event_t *event = NULL;
+        rd_kafka_topic_partition_list_t *partitions;
+        rd_kafka_ElectionType_t election_type;
+        rd_kafka_ElectLeader_t *elect_leader;
+        int i;
+        int retval = 0;
+
+        if(argc < 3){
+                usage("Invalid number of arguments");
+        }
+        int etype = parse_int("election_type", argv[0]);
+
+        if(etype == 0){
+                election_type = RD_KAFKA_ELECTION_TYPE_PREFERRED;
+        } else if(etype == 1){
+                election_type = RD_KAFKA_ELECTION_TYPE_UNCLEAN;
+        } else {
+                usage("Invalid election type");
+        }
+        argc--;
+        argv++;
+        partitions = rd_kafka_topic_partition_list_new(argc/2);
+        if(argc % 2 != 0){
+                usage("Invalid number of arguments");
+        }
+        for(i = 0; i < argc; i+=2){
+                rd_kafka_topic_partition_list_add(
+                    partitions, argv[i], parse_int("partition", argv[i+1]));
+        }
+
+        elect_leader = rd_kafka_ElectLeader_new(election_type, partitions);
+
+        /*
+         * Create consumer 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_CONSUMER, conf, errstr, sizeof(errstr));
+        if (!rk) {
+                usage("Failed to create new consumer: %s", errstr);
+        }
+
+        /*
+         * Elect Leaders
+         */
+        queue = rd_kafka_queue_new(rk);
+
+        /* Signal handler for clean shutdown */
+        signal(SIGINT, stop);
+
+
+        options = rd_kafka_AdminOptions_new(rk, RD_KAFKA_ADMIN_OP_ELECTLEADER);
+
+        if (rd_kafka_AdminOptions_set_request_timeout(
+                options, 10 * 1000 /* 10s */, errstr, sizeof(errstr))) {
+                fprintf(stderr, "%% Failed to set timeout: %s\n", errstr);
+                goto exit;
+        }
+
+        if(rd_kafka_AdminOptions_set_operation_timeout(
+                options, 10 * 1000 /* 10s */, errstr, sizeof(errstr))) {
+                fprintf(stderr, "%% Failed to set operation timeout: %s\n", errstr);
+                goto exit;
+        }
+
+        rd_kafka_ElectLeader(rk, elect_leader, options, queue);
+        rd_kafka_ElectLeader_destroy(elect_leader);
+        rd_kafka_AdminOptions_destroy(options);
+
+
+        /* Wait for results */
+        event = rd_kafka_queue_poll(queue, -1 /* indefinitely but limited by
+                                               * the request timeout set
+                                               * above (10s) */);
+
+        if (!event) {
+                /* User hit Ctrl-C,
+                 * see yield call in stop() signal handler */
+                fprintf(stderr, "%% Cancelled by user\n");
+
+        } else if (rd_kafka_event_error(event)) {
+                rd_kafka_resp_err_t err = rd_kafka_event_error(event);
+                /* ElectLeaders request failed */
+                fprintf(stderr, "%% ElectLeaders failed[%" PRId32 "]: %s\n", err,
+                        rd_kafka_event_error_string(event));
+                goto exit;
+        } else {
+                /* ElectLeaders request succeeded */
+                const rd_kafka_ElectLeader_result_t *result;
+                result = rd_kafka_event_ElectLeader_result(event);
+                retval = print_elect_leader_result(result);
+        }
+
+
+exit:
+        if (event)
+                rd_kafka_event_destroy(event);
+
+        rd_kafka_queue_destroy(queue);
+        /* Destroy the client instance */
+        rd_kafka_destroy(rk);
+
+        exit(retval);
+
+}
+
+
+int main(int argc, char **argv) {
+        rd_kafka_conf_t *conf; /**< Client configuration object */
+        int opt;
+        argv0 = argv[0];
+
+        /*
+         * Create Kafka client configuration place-holder
+         */
+        conf = rd_kafka_conf_new();
+
+
+        /*
+         * Parse common options
+         */
+        while ((opt = getopt(argc, argv, "b:X:d:")) != -1) {
+                switch (opt) {
+                case 'b':
+                        conf_set(conf, "bootstrap.servers", optarg);
+                        break;
+
+                case 'X': {
+                        char *name = optarg, *val;
+
+                        if (!(val = strchr(name, '=')))
+                                fatal("-X expects a name=value argument");
+
+                        *val = '\0';
+                        val++;
+
+                        conf_set(conf, name, val);
+                        break;
+                }
+
+                case 'd':
+                        conf_set(conf, "debug", optarg);
+                        break;
+
+                default:
+                        usage("Unknown option %c", (char)opt);
+                }
+        }
+
+        cmd_elect_leader(conf, argc - optind, &argv[optind]);
+
+        return 0;
+}