vinkal-chudgar commented on PR #24965:
URL: https://github.com/apache/pulsar/pull/24965#issuecomment-3515428703
> Why could take the method params into account ? There will be more request
to the broker, but the result is the same.
@Technoboy- The reason we must include these parameters in the key is that
they can lead to fundamentally different outcomes for the caller, breaking the
API contract if not handled separately. The logic within
`getPartitionedTopicMetadataAsync` demonstrates this.
```
if (!metadataAutoCreationEnabled &&
!clientCnx.isSupportsGetPartitionedMetadataWithoutAutoCreation()) {
if (useFallbackForNonPIP344Brokers) {
// Fall back to old behavior
finalAutoCreationEnabled = true;
} else {
// This path fails immediately
partitionFuture.completeExceptionally(new
PulsarClientException.FeatureNotSupportedException(...));
return;
}
}
// This path sends a request to the broker
ByteBuf request = Commands.newPartitionMetadataRequest(topicName.toString(),
requestId, finalAutoCreationEnabled);
```
Here is a practical example of why caching them separately is critical, as
two calls with the same `TopicName` but different parameters can produce
completely different results:
- **When the broker does not support PIP-344**, the outcome depends entirely
on the `useFallbackForNonPIP344Brokers` flag:
* One call might fail immediately with a
`FeatureNotSupportedException`.
* Another might fall back to the old behavior and succeed.
If we only deduped by `TopicName`, a caller that expects a failure could
incorrectly receive a successful result from the other caller. **This breaks
the method contract for that caller.**
- **Even when the broker supports PIP-344**, the
`metadataAutoCreationEnabled` flag changes the request sent. Coalescing
requests with different values for this flag hides the caller’s chosen behavior
and side effects (like topic auto-creation).
Regarding your point about increasing request volume: this change still
correctly deduplicates all concurrent calls that use the exact same parameters.
A new request is only sent when the parameters are different, ensuring we
respect the caller's intent while still preventing redundant traffic for
identical calls.
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