Added asyncio producer example

Author: mhowlett

examples/asyncio.py

@@ -0,0 +1,111 @@
+# Copyright 2019 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.
+
+# Companion code to the blog post "Integrating Kafka With Python Asyncio Web Applications"
+# https://www.confluent.io/blog/[path-to-blog-post]
+
+import asyncio
+from confluent_kafka import Producer
+from confluent_kafka import KafkaException
+from fastapi import FastAPI, HTTPException
+from pydantic import BaseModel
+from time import time
+from threading import Thread
+import uvicorn
+
+
+class AIOProducer:
+    def __init__(self, configs, loop):
+        self._loop = loop or asyncio.get_event_loop()
+        self._producer = Producer(configs)
+        self._cancelled = False
+        self._poll_thread = Thread(target=self._poll_loop)
+        self._poll_thread.start()
+
+    def _poll_loop(self):
+        while not self._cancelled:
+            self._producer.poll(0.1)
+
+    def close(self):
+        self._cancelled = True
+        self._poll_thread.join()
+
+    def async_produce(self, topic, value):
+        result = self._loop.create_future()
+        def ack(err, msg):
+            if err:
+                self._loop.call_soon_threadsafe(result.set_exception, KafkaException(err))
+            else:
+                self._loop.call_soon_threadsafe(result.set_result, msg)
+        self._producer.produce(topic, value, on_delivery=ack)
+        return result
+
+    def produce(self, topic, value, ack=None):
+        self._producer.produce(topic, value, on_delivery=ack)
+
+
+app = FastAPI()
+
+class Item(BaseModel):
+    name: str
+
+producer = None
+
+@app.on_event("startup")
+async def startup_event():
+    global producer
+    producer = AIOProducer(
+        {"bootstrap.servers": "localhost:9092"},
+        asyncio.get_event_loop())
+
+@app.on_event("shutdown")
+def shutdown_event():
+    producer.close()
+
+@app.post("/items1")
+async def create_item1(item: Item):
+    try:
+        result = await producer.async_produce("items", item.name)
+        return { "timestamp": result.timestamp() }
+    except KafkaException as ex:
+        raise HTTPException(status_code=500, detail=ex.args[0].str())
+
+cnt = 0
+def ack(err, msg):
+    global cnt
+    cnt = cnt + 1
+
+@app.post("/items2")
+async def create_item2(item: Item):
+    try:
+        result = producer.produce("items", item.name, ack=ack)
+        return { "timestamp": time() }
+    except KafkaException as ex:
+        raise HTTPException(status_code=500, detail=ex.args[0].str())
+
+@app.post("/items3")
+async def create_item3(item: Item):
+    try:
+        result = producer.produce("items", item.name)
+        return { "timestamp": time() }
+    except KafkaException as ex:
+        raise HTTPException(status_code=500, detail=ex.args[0].str())
+
+@app.post("/items4")
+async def create_item4(item: Item):
+    return { "timestamp": time() }
+
+
+if __name__ == '__main__':
+    uvicorn.run(app, host='0.0.0.0', port=8000)