Added "builtin.features" property to allow applications to query for built-in features (e.g., gzip, snappy, zlib)

Author: edenhill

examples/rdkafka_example.cpp

@@ -292,11 +292,13 @@ int main (int argc, char **argv) {
 
   if (mode.empty() || topic_str.empty() || optind != argc) {
   usage:
+	  std::string features;
+	  conf->get("builtin.features", features);
     fprintf(stderr,
             "Usage: %s [-C|-P] -t <topic> "
             "[-p <partition>] [-b <host1:port1,host2:port2,..>]\n"
             "\n"
-            "librdkafka version %s (0x%08x)\n"
+            "librdkafka version %s (0x%08x, builtin.features \"%s\")\n"
             "\n"
             " Options:\n"
             "  -C | -P         Consumer or Producer mode\n"
@@ -331,6 +333,7 @@ int main (int argc, char **argv) {
             "\n",
 	    argv[0],
 	    RdKafka::version_str().c_str(), RdKafka::version(),
+		features.c_str(),
 	    RdKafka::get_debug_contexts().c_str());
 	exit(1);
   }

src-cpp/rdkafkacpp.h

@@ -392,6 +392,10 @@ class RD_EXPORT Conf {
                                 RebalanceCb *rebalance_cb,
                                 std::string &errstr) = 0;
 
+  /* Query single configuration value */
+  virtual Conf::ConfResult get(const std::string &name,
+	  std::string &value) const = 0;
+
   /**
    * Dump configuration names and values to list containing name,value tuples
    */

src-cpp/rdkafkacpp_int.h

@@ -325,6 +325,34 @@ class ConfImpl : public Conf {
     return Conf::CONF_OK;
   }
 
+  Conf::ConfResult get(const std::string &name, std::string &value) const {
+	  size_t size;
+	  rd_kafka_conf_res_t res = RD_KAFKA_CONF_OK;
+	  if (rk_conf_) {
+		  if ((res = rd_kafka_conf_get(rk_conf_,
+			  name.c_str(), NULL, &size)) != RD_KAFKA_CONF_OK)
+			  return static_cast<Conf::ConfResult>(res);
+
+		  value.resize(size);
+		  if ((res = rd_kafka_conf_get(rk_conf_, name.c_str(),
+			  (char *)value.c_str(), &size)) != RD_KAFKA_CONF_OK)
+			  return static_cast<Conf::ConfResult>(res);
+	  }
+	  else if (rkt_conf_) {
+		  if ((res = rd_kafka_topic_conf_get(rkt_conf_,
+			  name.c_str(), NULL, &size)) != RD_KAFKA_CONF_OK)
+			  return static_cast<Conf::ConfResult>(res);
+
+		  value.resize(size);
+		  if ((res = rd_kafka_topic_conf_get(rkt_conf_, name.c_str(),
+			  (char *)value.c_str(), &size)) != RD_KAFKA_CONF_OK)
+			  return static_cast<Conf::ConfResult>(res);
+	  }
+
+	  return Conf::CONF_OK;
+  }
+
+
 
   std::list<std::string> *dump ();
 

src/rdkafka_conf.c

@@ -72,6 +72,24 @@ struct rd_kafka_property {
  */
 static const struct rd_kafka_property rd_kafka_properties[] = {
 	/* Global properties */
+	{ _RK_GLOBAL, "builtin.features", _RK_C_S2F, _RK(builtin_features),
+	"Indicates the builtin features for this build of librdkafka. "
+	"An application can either query this value or attempt to set it "
+	"with its list of required features to check for library support.",
+	0, 0x7fffffff, 0xff,
+	.s2i = {
+#if WITH_ZLIB
+		{ 0x1, "gzip" },
+#endif
+#ifndef _MSC_VER
+		{ 0x2, "snappy" },
+#endif
+#if WITH_SSL
+		{ 0x4, "ssl" },
+#endif
+		{ 0, NULL }
+		}
+	},
 	{ _RK_GLOBAL, "client.id", _RK_C_STR, _RK(client_id_str),
 	  "Client identifier.",
 	  .sdef =  "rdkafka" },

src/rdkafka_conf.h

@@ -86,6 +86,7 @@ struct rd_kafka_conf_s {
         /* Client group configuration */
         int    coord_query_intvl_ms;
 
+	int builtin_features;
 	/*
 	 * Consumer configuration
 	 */