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HardPrep Room Coding #2125

Compensating transaction may not execute

Code reviewDatabases & SQLReliability & on-callSenior–Staff~20 min

Review this Java method that reserves inventory, then charges the card, and undoes the reservation if the charge fails.

What a strong answer looks like

Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix, specific and kind.

0:00 of about 20 min
Mark a line and say what kind of problem it is.0 findings
1public void purchase(Order o) {
2 inventory.reserve(o.sku(), o.qty());
3 try {
4 payment.charge(o.card(), o.total());
5 } catch (ChargeException e) {
6 inventory.release(o.sku(), o.qty()); // compensate
7 throw e;
8 }
9}
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.