Refactor: Replace emptyReporter with DiscardReporter

[zJiaJun]

Purpose

This PR replaces the custom emptyReporter implementation in plugins/core/tracer.go with the existing reporter.NewDiscardReporter() to reduce code duplication and improve maintainability.

Changes

• Replace &emptyReporter{} with reporter.NewDiscardReporter() in the newTracer() method
• Remove the redundant emptyReporter struct and its method implementations

Motivation and Context

The emptyReporter and DiscardReporter have identical functionality - they both implement the Reporter interface but don't perform any actual operations. Using the existing DiscardReporter implementation reduces code duplication and follows the DRY principle.

[wu-sheng]

@mrproliu This seems to be a code level optimization only. We could keep this in 0.7?

[Copilot]

Pull Request Overview

This PR refactors the tracer functionality to reduce code duplication by replacing the custom emptyReporter with the existing DiscardReporter.

• Replaces the instantiation of &emptyReporter{} with reporter.NewDiscardReporter() in newTracer.
• Removes the emptyReporter type and its methods.
• Updates discard_reporter.go to return ConnectionStatusDisconnect for clarity.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
plugins/core/tracer.go	Replaces emptyReporter with DiscardReporter and removes unused code.
plugins/core/reporter/discard_reporter.go	Updates ConnectionStatus to return ConnectionStatusDisconnect.

[zJiaJun]

@mrproliu This seems to be a code level optimization only. We could keep this in 0.7?

@wu-sheng
I would like to propose adding a Kafka Reporter implementation to SkyWalking-Go to enhance its data reporting capabilities. This feature would allow users to send tracing data to Apache SkyWalking OAP server through Kafka, which is particularly beneficial in high-throughput environments

I would be happy to contribute to this implementation if the proposal is accepted. Please let me know your thoughts on this addition and any specific requirements or considerations I should be aware of.

[wu-sheng]

Kafka reporter is fine, as other agents have that.
The key is dependency management. We need to avoid impacting user app dependency tree.

[wu-sheng]

Kafka reporter is fine, as other agents have that.
The key is dependency management. We need to avoid impacting user app dependency tree.

It seems we don't have a way to avoid that.
Please go ahead, and let us pick latest kafka go client for this new feature.

[mrproliu]

@zJiaJun Hi, please fix the UT.

[zJiaJun]

@zJiaJun Hi, please fix the UT.

Fixed

[zJiaJun]

It seems we don't have a way to avoid that.
Please go ahead, and let us pick latest kafka go client for this new feature.

I'll start working on the Kafka Reporter implementation. It may take some time, and I plan to use segmentio/kafka-go v0.4.47 as the client library.

[wu-sheng]

It seems we don't have a way to avoid that.
Please go ahead, and let us pick latest kafka go client for this new feature.

I'll start working on the Kafka Reporter implementation. It may take some time, and I plan to use segmentio/kafka-go v0.4.47 as the client library.

Take your time. We have tagged 0.6 release. We have plenty time for 0.7.