idempotent

func DoIdempotent ¶

func DoIdempotent(ctx context.Context, store *redis.Redis, key string, v any, seconds, expired int, fn func(ctx context.Context, v any) error) (bool, error)

DoIdempotent ensures that for a given key the user function fn is executed at most once across distributed workers, and subsequent callers reuse the cached result.

• First caller:
• Tries cache; if miss, acquires a distributed lock, executes fn, stores the result in cache, and returns (false, nil).
• Concurrent callers:
• If cache already has the value, return (true, nil).
• If the lock is held by another worker, they wait up to `seconds` by polling the cache:
• If the value appears in cache during this window, return (true, nil).
• If it never appears, return an error (for example ErrorCacheEmpty or underlying Redis error).

seconds is the lock TTL in seconds and should be greater than the worst-case execution time of fn. expired is the cache TTL in seconds.