chore: add async example (#291)

Author: nachatz

examples/async.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+#
+
+# NOTE: requires version 3.9.0+ of pulsar-client library
+import asyncio
+from pulsar.asyncio import Client, Producer, Consumer
+from pulsar import BatchingType
+
+NUM_MESSAGES = 100
+TOPIC_NAME = 'my-async-topic'
+SUBSCRIPTION_NAME = 'my-async-subscription'
+SERVICE_URL = 'pulsar://localhost:6650'
+
+async def produce(producer: Producer, id: int) -> None:
+    await producer.send((f'hello-{id}').encode('utf-8'), None)
+    await producer.flush()
+
+async def consume(consumer: Consumer) -> None:
+    msg = await consumer.receive()
+    print("Received message '{0}' id='{1}'".format(msg.data().decode('utf-8'), msg.message_id()))
+    await consumer.acknowledge(msg)
+
+async def main() -> None:
+    client: Client = Client(SERVICE_URL)
+    consumer = await client.subscribe(TOPIC_NAME, SUBSCRIPTION_NAME,
+        properties={
+            "consumer-name": "test-consumer-name",
+            "consumer-id": "test-consumer-id"
+        })
+
+    producer = await client.create_producer(
+        TOPIC_NAME,
+        block_if_queue_full=True,
+        batching_enabled=True,
+        batching_max_publish_delay_ms=10,
+        properties={
+            "producer-name": "test-producer-name",
+            "producer-id": "test-producer-id"
+        },
+        batching_type=BatchingType.KeyBased
+    )
+
+    tasks = []
+    for id in range(NUM_MESSAGES):
+        tasks.append(asyncio.create_task(produce(producer, id)))
+        tasks.append(asyncio.create_task(consume(consumer)))
+    await asyncio.gather(*tasks)
+
+    await producer.close()
+    await consumer.close()
+    await client.close()
+
+if __name__ == '__main__':
+    asyncio.run(main())