[KAFKA-17153] KafkaMetricsGroup#newGauge should accept functional interface instead of `com.yammer.metrics.core.Gague`

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.9.0
• Assignee: Kuan Po Tseng
• Reporter: Chia-Ping Tsai
• Created: 16/Jul/24 22:45
• Updated: 21/Jul/24 10:17
• Resolved: 21/Jul/24 10:17

Description

This is a kind of syntactic sugar. Java disallow lambdas to implement abstract classes, and hence there are many ugly impl of Gague in code base [0][1][2][3]. Those bad looking code will spring up as we migrate more and more scala code to java.

Hence, we should offer a variety to accept functional interface for java code. For example:

    public final <T> Gauge<T> newGauge(String name, Supplier<T> metric) {
        return newGauge(name, new Gauge<T>() {
            @Override
            public T value() {
                return metric.get();
            }
        }, Collections.emptyMap());
    }

[0] https://github.com/apache/kafka/blob/b015a83f6d286965af999c39c0902584fb6fb9de/server/src/main/java/org/apache/kafka/server/AssignmentsManager.java#L109
[1] https://github.com/apache/kafka/blob/b015a83f6d286965af999c39c0902584fb6fb9de/metadata/src/main/java/org/apache/kafka/image/loader/metrics/MetadataLoaderMetrics.java#L73
[2] https://github.com/apache/kafka/blob/b015a83f6d286965af999c39c0902584fb6fb9de/metadata/src/main/java/org/apache/kafka/controller/metrics/ControllerMetadataMetrics.java#L106
[3] https://github.com/apache/kafka/blob/b015a83f6d286965af999c39c0902584fb6fb9de/storage/src/main/java/org/apache/kafka/storage/internals/log/RemoteStorageThreadPool.java#L54

Issue Links

• links to: GitHub Pull Request #16618