Reference library

Streaming & messaging

Kafka-style pub/sub, event consumers, async pipelines, and message-driven workflows.

4 matches

How to Build a Materialized View Updater Consumer Mock in Python

A mock consumer that queues change events and triggers refresh callbacks to simulate materialized view updates.

import time
from collections import deque
from dataclasses import dataclass, field
from typing import Callable, Deque, Optional


@dataclass
class MaterializedViewUpdater:
    """Mock updater that consumes change events and refreshes a view."""
    refresh: Optional[Callable[[str], None]] = None
    queue: Deque[tuple…

14 0 Open

Streaming & messaging easy

How to Implement Publish-Subscribe Fanout with Multiple Subscribers in Python

Create a simple publish-subscribe system in Python that broadcasts messages to multiple subscriber callbacks for a given topic.

pubsub messaging events

Python

import time

class PubSub:
    def __init__(self):
        self.subscribers = {}

    def subscribe(self, topic, callback):
        if topic not in self.subscribers:
            self.subscribers[topic] = []
        self.subscribers[topic].append(callback)

    def publish(self, topic, message):
        if topic in sel…

14 0 Open

Streaming & messaging easy

How to Implement an In-Memory Pub/Sub System in Python

This code implements a simple in-memory publish/subscribe system in Python, allowing topics, callbacks, and message broadcasting.

pubsub event-driven design-pattern

Python

class PubSub:
    def __init__(self):
        self.topics = {}

    def subscribe(self, topic, callback):
        if topic not in self.topics:
            self.topics[topic] = []
        self.topics[topic].append(callback)
        return lambda: self.unsubscribe(topic, callback)

    def unsubscribe(self, topic, callb…

18 0 Open

Streaming & messaging medium

How to Mock a Kafka Rebalance Listener in Python

Simulate Kafka consumer rebalance callbacks (on_partitions_revoked and on_partitions_assigned) with a mock consumer to test listener logic.

kafka rebalance mocking

Python

import time
from collections import defaultdict


class MockKafkaConsumer:
    def __init__(self):
        self.assignments = defaultdict(list)
        self.rebalances = 0

    def assign(self, partitions):
        self.rebalances += 1
        self.assignments.clear()
        for partition in partitions:
            s…

15 0 Open

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