Added (global) on_commit callback.

Consumer.c

@@ -37,6 +37,10 @@ static int Consumer_clear (Consumer *self) {
 		Py_DECREF(self->on_revoke);
 		self->on_revoke = NULL;
 	}
+	if (self->on_commit) {
+		Py_DECREF(self->on_commit);
+		self->on_commit = NULL;
+	}
 	return 0;
 }
 
@@ -543,6 +547,18 @@ PyTypeObject ConsumerType = {
 	"\n"
 	"  Create new Consumer instance using provided configuration dict.\n"
 	"\n"
+	" Special configuration properties:\n"
+	"   ``on_commit``: Optional callback will be called when a commit "
+	"request has succeeded or failed.\n"
+	"\n"
+	"\n"
+	".. py:function:: on_commit(consumer, err, partitions)\n"
+	"\n"
+	"  :param Consumer consumer: Consumer instance.\n"
+	"  :param KafkaError err: Commit error object, or None on success.\n"
+	"  :param list(TopicPartition) partitions: List of partitions with "
+	"their committed offsets or per-partition errors.\n"
+	"\n"
 	"\n", /*tp_doc*/
 	(traverseproc)Consumer_traverse, /* tp_traverse */
 	(inquiry)Consumer_clear, /* tp_clear */
@@ -622,6 +638,51 @@ static void Consumer_rebalance_cb (rd_kafka_t *rk, rd_kafka_resp_err_t err,
 }
 
 
+static void Consumer_offset_commit_cb (rd_kafka_t *rk, rd_kafka_resp_err_t err,
+				       rd_kafka_topic_partition_list_t *c_parts,
+				       void *opaque) {
+	Consumer *self = opaque;
+	PyObject *parts, *k_err, *args, *result;
+
+	if (!self->on_commit)
+		return;
+
+	PyEval_RestoreThread(self->thread_state);
+
+	/* Insantiate error object */
+	k_err = KafkaError_new_or_None(err, NULL);
+
+	/* Construct list of TopicPartition based on 'c_parts' */
+	parts = c_parts_to_py(c_parts);
+
+	args = Py_BuildValue("(OOO)", self, k_err, parts);
+
+	Py_DECREF(k_err);
+	Py_DECREF(parts);
+
+	if (!args) {
+		cfl_PyErr_Format(RD_KAFKA_RESP_ERR__FAIL,
+				 "Unable to build callback args");
+		self->thread_state = PyEval_SaveThread();
+		self->callback_crashed++;
+		return;
+	}
+
+	result = PyObject_CallObject(self->on_commit, args);
+
+	Py_DECREF(args);
+
+	if (result)
+		Py_DECREF(result);
+	else {
+		self->callback_crashed++;
+		rd_kafka_yield(rk);
+	}
+
+	self->thread_state = PyEval_SaveThread();
+}
+
+
 
 static PyObject *Consumer_new (PyTypeObject *type, PyObject *args,
 				   PyObject *kwargs) {
@@ -640,6 +701,7 @@ static PyObject *Consumer_new (PyTypeObject *type, PyObject *args,
 	}
 
 	rd_kafka_conf_set_rebalance_cb(conf, Consumer_rebalance_cb);
+	rd_kafka_conf_set_offset_commit_cb(conf, Consumer_offset_commit_cb);
 
 	self->rk = rd_kafka_new(RD_KAFKA_CONSUMER, conf,
 				errstr, sizeof(errstr));

confluent_kafka.c

@@ -966,6 +966,34 @@ static int producer_conf_set_special (Producer *self, rd_kafka_conf_t *conf,
 }
 
 
+/**
+ * @brief Set single special consumer config value.
+ *
+ * @returns 1 if handled, 0 if unknown, or -1 on failure (exception raised).
+ */
+static int consumer_conf_set_special (Consumer *self, rd_kafka_conf_t *conf,
+				      rd_kafka_topic_conf_t *tconf,
+				      const char *name, PyObject *valobj) {
+
+	if (!strcasecmp(name, "on_commit")) {
+		if (!PyCallable_Check(valobj)) {
+			cfl_PyErr_Format(
+				RD_KAFKA_RESP_ERR__INVALID_ARG,
+				"%s requires a callable "
+				"object", name);
+			return -1;
+		}
+
+		self->on_commit = valobj;
+		Py_INCREF(self->on_commit);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+
 /**
  * Common config setup for Kafka client handles.
  *
@@ -1004,6 +1032,7 @@ rd_kafka_conf_t *common_conf_setup (rd_kafka_type_t ktype,
 		const char *k;
 		const char *v;
 		char errstr[256];
+		int r;
 
 		if (!(ks = cfl_PyObject_Unistr(ko))) {
 			PyErr_SetString(PyExc_TypeError,
@@ -1028,24 +1057,22 @@ rd_kafka_conf_t *common_conf_setup (rd_kafka_type_t ktype,
 		}
 
 		/* Special handling for certain config keys. */
-		if (ktype == RD_KAFKA_PRODUCER) {
-			int r;
-
+		if (ktype == RD_KAFKA_PRODUCER)
 			r = producer_conf_set_special((Producer *)self0,
 						      conf, tconf, k, vo);
-			if (r == -1) {
-				/* Error */
-				Py_DECREF(ks);
-				rd_kafka_topic_conf_destroy(tconf);
-				rd_kafka_conf_destroy(conf);
-				return NULL;
-
-			} else if (r == 1) {
-				/* Handled */
-				continue;
-			}
+		else
+			r = consumer_conf_set_special((Consumer *)self0,
+						      conf, tconf, k, vo);
+		if (r == -1) {
+			/* Error */
+			Py_DECREF(ks);
+			rd_kafka_topic_conf_destroy(tconf);
+			rd_kafka_conf_destroy(conf);
+			return NULL;
 
-			/* FALLTHRU */
+		} else if (r == 1) {
+			/* Handled */
+			continue;
 		}
 
 

confluent_kafka.h

@@ -197,6 +197,7 @@ typedef struct {
 	int rebalance_assigned;  /* Rebalance: Callback performed assign() call.*/
 	PyObject *on_assign;     /* Rebalance: on_assign callback */
 	PyObject *on_revoke;     /* Rebalance: on_revoke callback */
+	PyObject *on_commit;     /* Commit callback */
 	int callback_crashed;
 	PyThreadState *thread_state;
 } Consumer;

docs/index.rst

@@ -21,6 +21,7 @@ providing a dict of configuration properties to the instance constructor, e.g.::
 
   conf = {'bootstrap.servers': 'mybroker.com',
           'group.id': 'mygroup', 'session.timeout.ms': 6000,
+          'on_commit': my_commit_callback,
           'default.topic.config': {'auto.offset.reset': 'smallest'}}
   consumer = confluent_kafka.Consumer(**conf)
 
@@ -40,5 +41,8 @@ The Python bindings also provide some additional configuration properties:
   This property may also be set per-message by passing ``callback=somefunc``
   to the confluent_kafka.Producer.produce() function.
 
+* ``on_commit`` (**Consumer**): Callback used to indicate success or failure
+  of commit requests.
+
 
 

integration_test.py

@@ -191,6 +191,13 @@ def verify_producer_performance(with_dr_cb=True):
           (t_delivery_spent - t_produce_spent))
 
 
+def print_commit_result (consumer, err, partitions):
+    if err is not None:
+        print('# Failed to commit offsets: %s: %s' % (err, partitions))
+    else:
+        print('# Committed offsets for: %s' % partitions)
+
+
 def verify_consumer():
     """ Verify basic Consumer functionality """
 
@@ -199,6 +206,7 @@ def verify_consumer():
             'group.id': 'test.py',
             'session.timeout.ms': 6000,
             'enable.auto.commit': False,
+            'on_commit': print_commit_result,
             'default.topic.config': {
                 'auto.offset.reset': 'earliest'
             }}

tests/test_Consumer.py

@@ -12,7 +12,11 @@ def test_basic_api():
     except TypeError as e:
         assert str(e) == "expected configuration dict"
 
-    kc = Consumer({'group.id':'test', 'socket.timeout.ms':'100'})
+    def dummy_commit_cb (consumer, err, partitions):
+        pass
+
+    kc = Consumer({'group.id':'test', 'socket.timeout.ms':'100',
+                   'on_commit': dummy_commit_cb})
 
     kc.subscribe(["test"])
     kc.unsubscribe()