sanpwc commented on code in PR #2820:
URL: https://github.com/apache/ignite-3/pull/2820#discussion_r1389504176
##########
modules/table/src/main/java/org/apache/ignite/internal/table/distributed/replicator/PartitionReplicaListener.java:
##########
@@ -2383,6 +2424,35 @@ private CompletableFuture<Object>
applyCmdWithExceptionHandling(Command cmd) {
});
}
+ private void applyCmdWithRetryOnSafeTimeReorderException(Command cmd,
CompletableFuture<Object> resultFuture) {
+ raftClient.run(cmd).whenComplete((res, ex) -> {
+ if (ex != null) {
+ if (ex instanceof SafeTimeReorderException || ex.getCause()
instanceof SafeTimeReorderException) {
+ assert cmd instanceof SafeTimePropagatingCommand;
+
+ SafeTimePropagatingCommand safeTimePropagatingCommand =
(SafeTimePropagatingCommand) cmd;
+
+ HybridTimestamp safeTimeForRetry = hybridClock.now();
+
+ if ((cmd instanceof UpdateCommand && !((UpdateCommand)
cmd).full())
Review Comment:
> Why is this condition needed? Could you please add a comment explaining
this?
Added.
```
// Within primary replica it's required to update safe time in order to
prevent double storage updates in case of !1PC.
// Otherwise, it may be possible that a newer entry will be overwritten by
an older one that came as part of the raft
// replication flow:
// tx1 = transactions.begin();
// tx1.put(k1, v1) -> primary.apply(k1,v1) + asynchronous raft replication
(k1,v1)
// tx1.put(k1, v2) -> primary.apply(k1,v2) + asynchronous raft replication
(k1,v1)
// (k1,v1) replication overrides newer (k1, v2). Eventually (k1,v2)
replication will restore proper value.
// However it's possible that tx1.get(k1) will see v1 instead of v2.
```
>
> Also, this check seems to be fragile. What if we add an analogous request
in the future, but forget to mention it here?
>
> How about adding a marker interface common for both update commands? It
might be more difficult to forget about it when adding a third 'update' command
in the future.
I agree that given solution is fragile. It should be refactored with
something more reliable in https://issues.apache.org/jira/browse/IGNITE-20124
TODO added. Here I'm talking not only about safeTime adjustment on retry but
about general double updates prevention logic.
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