Method cacheDurableMessage

coderd/x/chatd/chatd.go:4584–4599

cacheDurableMessage stores a recently persisted message event in the per-chat stream state so that same-replica subscribers can catch up from memory instead of the database. The afterMessageID is the message ID that precedes this message (i.e. message.ID - 1).

(chatID uuid.UUID, event codersdk.ChatStreamEvent)

// from memory instead of the database. The afterMessageID is the
// message ID that precedes this message (i.e. message.ID - 1).
func (p *Server) cacheDurableMessage(chatID uuid.UUID, event codersdk.ChatStreamEvent) {
	state := p.getOrCreateStreamState(chatID)
	state.mu.Lock()
	defer state.mu.Unlock()

	if len(state.durableMessages) >= maxDurableMessageCacheSize {
		if evicted := state.durableMessages[0]; evicted.Message != nil {
			state.durableEvictedBefore = evicted.Message.ID
		}
		// Zero the dropped slot so the evicted *ChatMessage is
		// GC-eligible; see publishToStream for the same pattern.
		state.durableMessages[0] = codersdk.ChatStreamEvent{}
		state.durableMessages = state.durableMessages[1:]
	}
	state.durableMessages = append(state.durableMessages, event)
}

// getCachedDurableMessages returns cached durable messages with IDs
// greater than afterID. Returns nil when the cache has no relevant