Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

Thanks for the suggested changes. Below are the comments:

1. Cluster: a transaction on 2 or more shards can pass when 1 shard has no replica acknowledgement

BatchResult.getSyncedSlaves() returns the sum of the WAIT replies from all masters in the batch. Refer to CommandBatchService, near L339 and L775.

2. Default options now cause commits to fail if a replica is slow

The default value of syncSlaves is 0, which means "all available slaves". Because of this value, createOptions() already sends WAIT <availableSlaves> for default transactions. The new check tests batchOptions.getSyncSlaves() > 0. As a result, the check applies to all default commits. It also applies to users who did not request replica sync.

3. The exception shows a failed transaction, but the master contains the data

WAIT does not cancel the write. After each exception in my tests, the master contained the value. At that point, executed is already true, so a rollback() call is not possible.

The exception type is also the same as for "Unable to execute transaction". In that case, Redisson wrote no data. RedissonTransactionManager.doCommit changes the exception to TransactionSystemException. If the application retries a failed transaction, it applies the writes two times.

Can you use a subclass for this exception? For example, TransactionSyncException extends TransactionException. With a subclass, the current catch blocks continue to work. The message must tell what occurred, for example: Transaction committed, but only 2 of 3 replicas acknowledged within 2000 ms. Also, update the syncSlaves Javadoc and docs/transactions.md with the new behaviour.

4. The test does not test the change

RedissonTransactionSyncSlavesTest only examines the getters, equals and hashCode of TransactionOptions. Thus, the test passes if you remove the fix.

Minor items

• createOptions() changed from private to package-private, but no code uses it. Make it private again.
• The check occurs two times, in commit and in commitAsync. One small private method can contain the check for both.