Kirjeldage väljamakseoperatsioonide idempotentsusmehhanismi: kus hoiti võtit, milline oli TTL, kuidas käsitleti kokkupõrkeid

The idempotency mechanism of write operations is usually implemented by storing a unique operation key (for example, UUID or request hash) in a fast storage with a limited lifetime (TTL).

• Where the key is stored: the operation key is stored in a distributed cache or database that supports TTL, such as Redis.
• TTL: the lifetime of the key is set according to business logic, for example, 5-10 minutes, to prevent repeated charges in a short period.
• Collision handling: upon receiving a request with an existing key, the operation is not repeated, but the result of the previous call is returned. If the key does not exist, the operation is executed and the key is stored.

This approach ensures that repeated requests with the same key do not lead to double charging, ensuring idempotency.