Idempotence now prevents pain later • Hacker News Board

Re: Idempotence now prevents pain later

#131

Post by tareqak » Sat, Apr 10, 2021, 11:26 AM UTC

gregmac wrote: post #88

I have worked on lots of software that involves event-driven actions, and apply this concept throughout. "Need to send a notification email when x condition becomes true". Naive way: during processing, check the condition and call the SendEmail() function. Idempotent way: Run a query that finds all x conditions, join to a list of notifications based on email+id+time, and only if there's no entry, send the notificatio…

The idempotent way is definitely better, but I argue/add that it would be better to have the incoming business requirement phrased appropriately such that the idempotent approach is the first one that comes to mind.

I am not sure how to perform that rewording/transformation in general though or even for the examples above.

Re: Idempotence now prevents pain later

#132

Post by xnx » Sat, Apr 10, 2021, 7:47 PM UTC

gregmac wrote: post #88

I have worked on lots of software that involves event-driven actions, and apply this concept throughout. "Need to send a notification email when x condition becomes true". Naive way: during processing, check the condition and call the SendEmail() function. Idempotent way: Run a query that finds all x conditions, join to a list of notifications based on email+id+time, and only if there's no entry, send the notificatio…

I've set up a bunch of Windows batch scripts similarly, but didn't know the name for it. It's beautiful because failures, crashes, bugs, restarts, etc. barely matter. The next time the system is able to do what it was supposed to do, it does.

Re: Idempotence now prevents pain later

#133

Post by kyrra » Sun, Apr 11, 2021, 12:20 AM UTC

speedgoose wrote: post #79

kyrra wrote: post #51

Googler opinions are my own. I work on payments stuff. Payments at Google defined some specs for payment companies to build to, which allows easy onboarding as a form of payment on google's platform. We have a page talking about idempotency and expected behavior. https://developers.google.com/standard-payments/reference/id... I don't think it's that different from other payment companies, like adyen or worldpay, but…

Sorry if it's a bit off topic but are you required by your employer to tell us you work from them and whether your opinion represents them or not? I read such disclaimers a lot about people working in your company, but extremely rarely for any other company.

Google has some wording in our contract thst says we are required to put a disclaimer when we're posting publicly, I don't remember the exact wording, but I always include it on any topic that is even tangentially related to the company.

This is actually a lot better than previous companies. My employee contract when I was at Cisco, basically said I couldn't talk about anything Cisco related on the internet without sign off from upper management or PR or something.