[GitHub] [cassandra-accord] belliottsmith commented on a diff in pull request #12: Add transaction expiration

[GitBox <gi...@apache.org>]

belliottsmith commented on code in PR #12:
URL: https://github.com/apache/cassandra-accord/pull/12#discussion_r1018307936


##########
accord-core/src/main/java/accord/impl/InMemoryCommandStore.java:
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@@ -163,7 +157,17 @@ public long latestEpoch()
         }
 
         @Override
-        public Timestamp maxConflict(Keys keys)
+        public Timestamp preaccept(TxnId txnId, Keys keys)
+        {
+            Timestamp max = maxConflict(keys);
+            long epoch = latestEpoch();
+            if (txnId.compareTo(max) > 0 && txnId.epoch >= epoch && !agent.isExpired(txnId, time.now()))

Review Comment:
   This permits a majority of remote replicas to also collectively reject an expired transaction received from a long running coordinator  - and also means that recovery doesn't accidentally register a preaccept that can be counted towards the original coordination. Though perhaps for that we should just explicitly refuse to use the original ballot for recovery.
   
   This is all sort of arbitrary, so happy with any of these approaches.



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