How to solve the problem of lost messages and lack of delivery guarantee in Redis pub/sub for chess?

Redis pub/sub does not guarantee message delivery: if the subscriber is disconnected or cannot process the message in time, it is lost. For chess, where reliable move delivery is crucial, this is critical.

Solutions:

1. Use Redis Streams instead of pub/sub. Streams store messages, and the client can read them from the desired position, ensuring guaranteed delivery.

2. Implement acknowledgments (ACK) at the application level: after receiving a message, the client sends an acknowledgment, and the server resends if no ACK is received.

3. Store game state and recent moves in a database so that upon reconnection, the client can request missed events.

Example of using Redis Streams in Go:

// Write a move to the stream
client.XAdd(&redis.XAddArgs{
    Stream: "chess_moves",
    Values: map[string]interface{}{"move": "e2e4", "game_id": "123"},
})

// Read moves from a position
client.XRead(&redis.XReadArgs{
    Streams: []string{"chess_moves", "0"},
    Count:  10,
    Block:  0,
})

Thus, it is possible to ensure reliable message delivery and avoid losses.