Replay Buffer

Same API as the core createReplay plugin, but backed by Redis sorted sets. Messages survive restarts and are shared across instances.

When to use over the built-in plugin: The core replay buffer lives in process memory - it is lost on restart and not shared between instances. Use the Redis version when you need message history that survives deploys or is consistent across a cluster.

Setup

// src/lib/server/replay.js
import { redis } from './redis.js';
import { createReplay } from 'svelte-adapter-uws-extensions/redis/replay';

export const replay = createReplay(redis, {
  size: 500,
  ttl: 3600  // expire after 1 hour
});

Usage

// In a form action or API route
export const actions = {
  send: async ({ request, platform }) => {
    const data = Object.fromEntries(await request.formData());
    const msg = await db.createMessage(data);
    await replay.publish(platform, 'chat', 'created', msg);
  }
};

// In +page.server.js
export async function load() {
  const messages = await db.getRecentMessages();
  return { messages, seq: await replay.seq('chat') };
}

// In hooks.ws.js - handle replay requests
export async function message(ws, { data, platform }) {
  const msg = JSON.parse(Buffer.from(data).toString());
  if (msg.type === 'replay') {
    await replay.replay(ws, msg.topic, msg.since, platform);
    return;
  }
}

Options

API

All methods are async (they hit Redis). The API otherwise matches the core plugin exactly: