Changed the order of things

also fixed spelling of amqp

src/magic_amqp.py

@@ -0,0 +1,121 @@
+from flask import Flask
+from threading import Lock
+import pika
+import pika.exceptions
+import json
+import time
+
+
+class MagicAMQP:
+    """
+    This is my pathetic attempt to make RabbitMQ connection in a Flask app reliable and performant.
+    """
+
+    def __init__(self, app: Flask = None):
+        self.app = app
+        if app:
+            self.init_app(app)
+
+        self._lock = Lock()
+        self._credentials = None
+
+    def init_app(self, app: Flask):
+        self.app = app
+        self.app.config.setdefault('FLASK_PIKA_PARAMS', {})
+        self.app.config.setdefault('EXCHANGE_NAME', None)
+        self.app.config.setdefault('RABBITMQ_QUEUE', None)
+
+        self._credentials = pika.PlainCredentials(
+            app.config['FLASK_PIKA_PARAMS']['username'],
+            app.config['FLASK_PIKA_PARAMS']['password']
+        )
+
+        self._reconnect_ampq()
+
+    def _reconnect_ampq(self):
+        self._pika_connection = pika.BlockingConnection(
+            pika.ConnectionParameters(
+                host=self.app.config['FLASK_PIKA_PARAMS']['host'],
+                credentials=self._credentials,
+                heartbeat=10,
+                socket_timeout=5)
+        )
+        self._pika_channel = self._pika_connection.channel()
+        self._pika_channel.exchange_declare(
+            exchange=self.app.config['EXCHANGE_NAME'],
+            exchange_type='direct'
+        )
+
+    def loop(self):
+        """
+        This method should be called periodically to keep up the connection
+        """
+        lock_start = time.time()
+        with self._lock:
+            lock_acquire_time = time.time() - lock_start
+            if lock_acquire_time >= 0.5:
+                self.app.logger.warning(f"Loop: Lock acquire took {lock_acquire_time:5f} sec")
+
+            try:
+                self._pika_connection.process_data_events(0)
+                # We won't attempt retry if this fail
+            except pika.exceptions.AMQPConnectionError as e:
+                self.app.logger.warning(f"Connection error during process loop: {e} (attempting reconnect)")
+                self._reconnect_ampq()
+
+            total_time = time.time() - lock_start
+            if total_time > 1:
+                self.app.logger.warning(f"Loop: Total loop took {total_time:5f} sec")
+
+    def publish(self, payload=None):
+        """
+        Publish a simple json serialized message to the configured queue.
+        If the connection is broken, then this call will block until the connection is restored
+        """
+        lock_start = time.time()
+        with self._lock:
+            lock_acquire_time = time.time() - lock_start
+            if lock_acquire_time >= 0.2:
+                self.app.logger.warning(f"Publish: Lock acquire took {lock_acquire_time:5f} sec")
+            tries = 0
+            while True:
+                try:
+                    self._pika_channel.basic_publish(
+                        exchange=self.app.config['EXCHANGE_NAME'],
+                        routing_key='feature',
+                        body=json.dumps(payload).encode('UTF-8')
+                    )
+                    break  # message sent successfully
+                except pika.exceptions.AMQPConnectionError as e:
+                    self.app.logger.warning(f"Connection error during publish: {e} (attempting reconnect)")
+
+                    if tries > 30:
+                        raise  # just give up
+
+                    while True:
+                        try:
+                            self._reconnect_ampq()
+                            break
+                        except pika.exceptions.AMQPConnectionError as e:
+                            self.app.logger.warning(f"Connection error during reconnection: {e} (attempting reconnect)")
+                            tries += 1
+
+                            if tries > 30:
+                                raise  # just give up
+
+                        if tries > 10:
+                            time.sleep(2)
+            total_time = time.time() - lock_start
+            if total_time > 0.4:
+                self.app.logger.warning(f"Publish: Total publish took {total_time:5f} sec")
+
+    def is_healthy(self) -> bool:
+        with self._lock:
+            if not self._pika_channel:
+                return False
+
+            return self._pika_channel.is_open and self._pika_connection.is_open
+
+
+# instance to be used in the flask app
+magic_amqp = MagicAMQP()