ElectLeaders api(KIP-460) implemented (#1818)

* electLeaders

* requested changes

* requested changes

* style fix

* requested changes

* whitespace error

* changes acc to new format

* requested changes

* whitespace error

* line break

* line break

* indentation changes

Author: PratRanj07

examples/adminapi.py

@@ -26,7 +26,7 @@
                                    AclOperation, AclPermissionType, AlterConfigOpType,
                                    ScramMechanism, ScramCredentialInfo,
                                    UserScramCredentialUpsertion, UserScramCredentialDeletion,
-                                   OffsetSpec)
+                                   OffsetSpec, ElectionType)
 import sys
 import threading
 import logging
@@ -878,6 +878,36 @@ def example_delete_records(a, args):
                 f" before offset {partition.offset}: {e}")
 
 
+def example_elect_leaders(a, args):
+    partitions = []
+    if (len(args) - 1) % 2 != 0:
+        raise ValueError("Invalid number of arguments for elect_leaders, Expected format: " +
+                         "elect_leaders <election_type> [<topic1> <partition1>" +
+                         " <topic2> <partition2> ..]")
+
+    try:
+        election_type = ElectionType[args[0]]
+    except KeyError:
+        raise ValueError(f"Invalid election_type: {args[0]}, expected 'PREFERRED' or 'UNCLEAN'")
+
+    for topic, partition in zip(args[1::2], args[2::2]):
+        partitions.append(TopicPartition(topic, int(partition)))
+
+    f = a.elect_leaders(election_type, partitions)
+    try:
+        results = f.result()
+        for partition, exception in results.items():
+            if exception is None:
+                print(f"Leader Election Successful for topic: '{partition.topic}'" +
+                      f" partition: '{partition.partition}'")
+            else:
+                print(
+                    "Leader Election Failed for topic: " +
+                    f"'{partition.topic}' partition: '{partition.partition}': {exception}")
+    except KafkaException as e:
+        print(f"Error electing leaders: {e}")
+
+
 if __name__ == '__main__':
     if len(sys.argv) < 3:
         sys.stderr.write('Usage: %s <bootstrap-brokers> <operation> <args..>\n\n' % sys.argv[0])
@@ -917,6 +947,7 @@ def example_delete_records(a, args):
         sys.stderr.write(' list_offsets <isolation_level> <topic1> <partition1> <offset_spec1> ' +
                          '[<topic2> <partition2> <offset_spec2> ..]\n')
         sys.stderr.write(' delete_records <topic1> <partition1> <offset1> [<topic2> <partition2> <offset2> ..]\n')
+        sys.stderr.write(' elect_leaders <election_type> [<topic1> <partition1> <topic2> <partition2> ..]\n')
         sys.exit(1)
 
     broker = sys.argv[1]
@@ -947,7 +978,8 @@ def example_delete_records(a, args):
               'describe_user_scram_credentials': example_describe_user_scram_credentials,
               'alter_user_scram_credentials': example_alter_user_scram_credentials,
               'list_offsets': example_list_offsets,
-              'delete_records': example_delete_records}
+              'delete_records': example_delete_records,
+              'elect_leaders': example_elect_leaders}
 
     if operation not in opsmap:
         sys.stderr.write('Unknown operation: %s\n' % operation)

src/confluent_kafka/admin/__init__.py

@@ -54,6 +54,8 @@
 from ._listoffsets import (OffsetSpec,  # noqa: F401
                            ListOffsetsResultInfo)
 
+from ._election import (ElectionType)  # noqa: F401
+
 from ._records import DeletedRecords  # noqa: F401
 
 from .._model import TopicCollection as _TopicCollection
@@ -548,6 +550,22 @@ def _check_delete_records(request):
             if req.partition < 0:
                 raise ValueError("'partition' cannot be negative")
 
+    @staticmethod
+    def _check_elect_leaders(election_type, partitions):
+        if not isinstance(election_type, ElectionType):
+            raise TypeError("Expected 'election_type' to be of type 'ElectionType'")
+        if partitions is not None:
+            if not isinstance(partitions, list):
+                raise TypeError("Expected 'partitions' to be a list, got " +
+                                f"'{type(partitions).__name__}'")
+            for partition in partitions:
+                if not isinstance(partition, _TopicPartition):
+                    raise TypeError("Element of the 'partitions' list must be of type 'TopicPartition'" +
+                                    f" got '{type(partition).__name__}' ")
+                if partition.partition < 0:
+                    raise ValueError("Elements of the 'partitions' list must not have negative value" +
+                                     " for 'partition' field")
+
     def create_topics(self, new_topics, **kwargs):
         """
         Create one or more new topics.
@@ -1258,3 +1276,38 @@ def delete_records(self, topic_partition_offsets, **kwargs):
 
         super(AdminClient, self).delete_records(topic_partition_offsets, f, **kwargs)
         return futmap
+
+    def elect_leaders(self, election_type, partitions=None, **kwargs):
+        """
+        Perform Preferred or Unclean leader election for
+        all the specified topic partitions.
+
+        :param ElectionType election_type: The type of election to perform.
+        :param List[TopicPartition]|None partitions: The topic partitions to perform
+               the election on. Use ``None`` to perform on all the topic partitions.
+        :param float request_timeout: The overall request timeout in seconds,
+               including broker lookup, request transmission, operation time
+               on broker, and response. Default: `socket.timeout.ms*1000.0`
+        :param float operation_timeout: The operation timeout in seconds,
+               controlling how long the 'elect_leaders' request will block
+               on the broker waiting for the election to propagate
+               in the cluster. A value of 0 returns immediately.
+               Default: `socket.timeout.ms/1000.0`
+
+        :returns: A future. Method result() of the future returns
+                  dict[TopicPartition, KafkaException|None].
+
+        :rtype: future
+
+        :raises KafkaException: Operation failed locally or on broker.
+        :raises TypeError: Invalid input type.
+        :raises ValueError: Invalid input value.
+        """
+
+        AdminClient._check_elect_leaders(election_type, partitions)
+
+        f = AdminClient._create_future()
+
+        super(AdminClient, self).elect_leaders(election_type.value, partitions, f, **kwargs)
+
+        return f

src/confluent_kafka/admin/_election.py

@@ -0,0 +1,29 @@
+# Copyright 2024 Confluent Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from enum import Enum
+from .. import cimpl as _cimpl
+
+
+class ElectionType(Enum):
+    """
+    Enumerates the different types of leader elections.
+    """
+    PREFERRED = _cimpl.ELECTION_TYPE_PREFERRED  #: Preferred election
+    UNCLEAN = _cimpl.ELECTION_TYPE_UNCLEAN  #: Unclean election
+
+    def __lt__(self, other):
+        if self.__class__ != other.__class__:
+            return NotImplemented
+        return self.value < other.value

src/confluent_kafka/src/Admin.c

@@ -3059,6 +3059,104 @@ const char Admin_delete_records_doc[] = PyDoc_STR(
         "\n"
         "  This method should not be used directly, use confluent_kafka.AdminClient.delete_records()\n");
 
+/**
+ * @brief Elect leaders
+ */
+PyObject *Admin_elect_leaders(Handle *self, PyObject *args, PyObject *kwargs) {
+        PyObject *election_type = NULL, *partitions = NULL, *future;
+        rd_kafka_ElectLeaders_t *c_elect_leaders = NULL;
+        rd_kafka_ElectionType_t c_election_type;
+        struct Admin_options options       = Admin_options_INITIALIZER;
+        rd_kafka_AdminOptions_t *c_options = NULL;
+        rd_kafka_topic_partition_list_t *c_partitions = NULL;
+        CallState cs;
+        rd_kafka_queue_t *rkqu;
+
+        static char *kws[] = {"election_type",
+                              "partitions"
+                              "future",
+                              /* options */
+                              "request_timeout", "operation_timeout", NULL};
+
+        if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OOO|ff", kws,
+                                         &election_type, &partitions, &future,
+                                         &options.request_timeout,
+                                         &options.operation_timeout)) {
+                goto err;
+        }
+
+        c_options = Admin_options_to_c(self, RD_KAFKA_ADMIN_OP_ELECTLEADERS,
+                                       &options, future);
+        if (!c_options) {
+                goto err; /* Exception raised by options_to_c() */
+        }
+
+        /* options_to_c() sets future as the opaque, which is used in the
+         * background_event_cb to set the results on the future as the
+         * admin operation is finished, so we need to keep our own refcount. */
+        Py_INCREF(future);
+
+        c_election_type = (rd_kafka_ElectionType_t)cfl_PyInt_AsInt(election_type);
+
+        if (partitions != Py_None && !PyList_Check(partitions)) {
+                PyErr_SetString(PyExc_ValueError, "partitions must be None or a list");
+                goto err;
+        }
+
+        if (partitions != Py_None) {
+                c_partitions = py_to_c_parts(partitions);
+        }
+
+        c_elect_leaders = rd_kafka_ElectLeaders_new(c_election_type, c_partitions);
+        
+        if(c_partitions) {
+                rd_kafka_topic_partition_list_destroy(c_partitions);
+        }
+
+        /* Use librdkafka's background thread queue to automatically dispatch
+         * Admin_background_event_cb() when the admin operation is finished. */
+        rkqu = rd_kafka_queue_get_background(self->rk);
+
+        /**
+         *
+         * Call ElectLeaders
+         *
+         * We need to set up a CallState and release GIL here since
+         * the event_cb may be triggered immediately.
+         *
+         */
+        CallState_begin(self, &cs);
+        rd_kafka_ElectLeaders(self->rk, c_elect_leaders, c_options, rkqu);
+        CallState_end(self, &cs);
+
+        rd_kafka_queue_destroy(rkqu); /* drop reference from get_background */
+
+        rd_kafka_AdminOptions_destroy(c_options);
+        rd_kafka_ElectLeaders_destroy(c_elect_leaders);
+
+        Py_RETURN_NONE;
+
+err:
+        if (c_elect_leaders) {
+                rd_kafka_ElectLeaders_destroy(c_elect_leaders);
+        }
+        if (c_options) {
+                rd_kafka_AdminOptions_destroy(c_options);
+                Py_DECREF(future);
+        }
+        return NULL;
+}
+
+const char Admin_elect_leaders_doc[] = PyDoc_STR(
+    ".. py:function:: elect_leaders(election_type, partitions, "
+    "future, [request_timeout, operation_timeout])\n"
+    "\n"
+    "  Perform Preferred or Unclean election for the specified "
+    "Topic Partitions.\n"
+    "\n"
+    "  This method should not be used directly, use "
+    "confluent_kafka.AdminClient.elect_leaders()\n");
+
 /**
  * @brief Call rd_kafka_poll() and keep track of crashing callbacks.
  * @returns -1 if callback crashed (or poll() failed), else the number
@@ -3225,6 +3323,10 @@ static PyMethodDef Admin_methods[] = {
            Admin_delete_records_doc
         },
 
+        { "elect_leaders", (PyCFunction)Admin_elect_leaders, METH_VARARGS | METH_KEYWORDS, 
+           Admin_elect_leaders_doc
+        },
+
         { NULL }
 };
 
@@ -4875,6 +4977,23 @@ static void Admin_background_event_cb (rd_kafka_t *rk, rd_kafka_event_t *rkev,
                 break;
         }
 
+        case RD_KAFKA_EVENT_ELECTLEADERS_RESULT: 
+        {
+                size_t c_result_cnt;
+
+                const rd_kafka_ElectLeaders_result_t
+                    *c_elect_leaders_res_event =
+                        rd_kafka_event_ElectLeaders_result(rkev);
+
+                const rd_kafka_topic_partition_result_t **partition_results =
+                        rd_kafka_ElectLeaders_result_partitions(
+                            c_elect_leaders_res_event, &c_result_cnt);
+
+                result = c_topic_partition_result_to_py_dict(partition_results, c_result_cnt);
+
+                break;
+        }
+
         default:
                 Py_DECREF(error); /* Py_None */
                 error = KafkaError_new0(RD_KAFKA_RESP_ERR__UNSUPPORTED_FEATURE,

src/confluent_kafka/src/AdminTypes.c

@@ -597,6 +597,14 @@ static void AdminTypes_AddObjectsOffsetSpec (PyObject *m) {
         PyModule_AddIntConstant(m,"OFFSET_SPEC_LATEST", RD_KAFKA_OFFSET_SPEC_LATEST);
 }
 
+static void AdminTypes_AddObjectsElectionType(PyObject *m) {
+        /* rd_kafka_ElectionType_t */
+        PyModule_AddIntConstant(m, "ELECTION_TYPE_PREFERRED",
+                                RD_KAFKA_ELECTION_TYPE_PREFERRED);
+        PyModule_AddIntConstant(m, "ELECTION_TYPE_UNCLEAN",
+                                RD_KAFKA_ELECTION_TYPE_UNCLEAN);
+}
+
 /**
  * @brief Add Admin types to module
  */
@@ -616,4 +624,5 @@ void AdminTypes_AddObjects (PyObject *m) {
         AdminTypes_AddObjectsScramMechanismType(m);
         AdminTypes_AddObjectsIsolationLevel(m);
         AdminTypes_AddObjectsOffsetSpec(m);
+        AdminTypes_AddObjectsElectionType(m);
 }