kamalcph commented on code in PR #20913:
URL: https://github.com/apache/kafka/pull/20913#discussion_r3199747635
##########
storage/src/main/java/org/apache/kafka/storage/internals/log/LogConfig.java:
##########
@@ -399,6 +411,15 @@ public Boolean remoteLogCopyDisable() {
return remoteLogConfig.remoteLogCopyDisable;
}
+
+ public long remoteCopyLagMs() {
+ return remoteLogConfig.remoteCopyLagMs == MAX_REMOTE_COPY_LAG_MS ?
localRetentionMs() : remoteLogConfig.remoteCopyLagMs;
Review Comment:
> using -1 or Long.MaxValue to reach the max delay lag
Both usages are fine. From the KIP discussion:
```
3) if set to a value in between: it creates a buffer windows. users can save
costs for a period but still upload data well before it hits the retention
limit, avoiding burst traffic issues
```
Most likely users will configure a positive value to have buffer window.
(eg) Topic-A is configured with
retention.ms = 2 days
local.retention.ms = 3 hrs
remote.copy.lag.ms = 2.5 hrs
Whenever you reduce the `local.rentention.ms`, then you also may have to
reduce the `remote.copy.lag.ms` otherwise the validation might throw an error.
With the internal logic `max(0, min(copy_lag, local_retention))`, it can take
the lower of both config.
When `remote.copy.lag.ms ` is set to -1 and `local.retention.ms` is set to
-2, then the value of copy lag gets derived from `retention.ms`. This is the
concern that the value is derived from two other configs. I think usage of
either -1 or Long.MaxValue is fine.
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