[SCB-1707] Forward compensation only sends once a failure event if multiple retries fail

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: pack-0.6.0
• Component/s: Saga
• Assignee: Lei Zhang
• Reporter: Lei Zhang
• Created: 07/Jan/20 14:59
• Updated: 23/Jun/23 19:29
• Resolved: 13/Jan/20 06:10

Description

Forward compensation will retry after the call fails until the maximum number of retries is exceeded. It calls the reverse compensate applyTo method with each retry. This will cause multiple TxStartedEvent and TxAbortEvent to be sent. Test case [1] proves this.
 
For example, retries=2, the first failure, and the second success, Alpha will receive the following events
 
TxStartedEvent-tx1 (first)
TxAbortEvent-tx1（This will trigger the compensation operation）
TxStartedEvent-tx1 (second)
TxEndedEvent-tx1 (tx1 will be submitted)
 
I suggest sending the TxAbortEvent event only if the last forward retry failed. The modified event list looks as follows
 
Example 1: retries=3 and retry all failed
 
TxStartedEvent-tx1
TxStartedEvent-tx1
TxStartedEvent-tx1
TxAbortEvent-tx1(Trigger compensation operation)
 
Example 2: retries=3 and last retry succeeded
 
TxStartedEvent-tx1
TxStartedEvent-tx1
TxStartedEvent-tx1
TxEndedEvent-tx1 
[1] https://github.com/apache/servicecomb-pack/blob/133a2fa7247b2ba00a380762a38369849390560e/omega/omega-transaction/src/test/java/org/apache/servicecomb/pack/omega/transaction/TransactionAspectTest.java#L309 tx/src/test/java/org/apache/servicecomb/pack/omega/transaction/spring/TransactionInterceptionTest.java#L199
 
[3] https://github.com/apache/servicecomb-pack/blob/133a2fa7247b2ba00a380762a38369849390560e/omega/omega-transaction/src/test/java/org/apache/servicecomb/pack/omega/transaction/TransactionAspectTest.java#L353
 

Issue Links

• links to: GitHub Pull Request #630