mumrah commented on a change in pull request #8691:
URL: https://github.com/apache/kafka/pull/8691#discussion_r430482879
##########
File path: core/src/main/scala/kafka/server/KafkaServer.scala
##########
@@ -129,7 +129,10 @@ class KafkaServer(val config: KafkaConfig, time: Time =
Time.SYSTEM, threadNameP
private var shutdownLatch = new CountDownLatch(1)
+ //properties for MetricsContext
Review comment:
This comment was just about the `jmxPrefix` variable. I realize it's
pre-existing code, but now that it's not specific to JMX, I suggested renaming
it.
##########
File path:
clients/src/main/java/org/apache/kafka/common/metrics/MetricsContext.java
##########
@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.metrics;
+
+import org.apache.kafka.common.annotation.InterfaceStability;
+
+import java.util.Map;
+
+/**
+ * MetricsContext encapsulates additional metadata about metrics exposed via a
+ * {@link org.apache.kafka.common.metrics.MetricsReporter}
+ *
+ * The metadata map provides following information:
+ * - a <code>_namespace</node> field indicating the component exposing metrics
+ * e.g. kafka.server, kafka.consumer
+ * {@link JmxReporter} uses this as prefix for mbean names
+ *
+ * - for clients and streams libraries: any freeform fields passed in via
+ * client properties in the form of `metrics.context.<key>=<value>
+ *
+ * - for kafka brokers: kafka.broker.id, kafka.cluster.id
+ * - for connect workers: connect.kafka.cluster.id, connect.group.id
+ */
+@InterfaceStability.Evolving
+public interface MetricsContext {
+ /* predefined fields */
+ String NAMESPACE = "_namespace"; // metrics namespace, formerly jmx prefix
+
+ /**
+ * Returns metadata fields
+ */
+ Map<String, String> metadata();
Review comment:
That sounds good
##########
File path:
clients/src/main/java/org/apache/kafka/common/metrics/MetricsContext.java
##########
@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.metrics;
+
+import org.apache.kafka.common.annotation.InterfaceStability;
+
+import java.util.Map;
+
+/**
+ * MetricsContext encapsulates additional metadata about metrics exposed via a
+ * {@link org.apache.kafka.common.metrics.MetricsReporter}
+ *
+ * The metadata map provides following information:
+ * - a <code>_namespace</node> field indicating the component exposing metrics
+ * e.g. kafka.server, kafka.consumer
+ * {@link JmxReporter} uses this as prefix for mbean names
+ *
+ * - for clients and streams libraries: any freeform fields passed in via
+ * client properties in the form of `metrics.context.<key>=<value>
+ *
+ * - for kafka brokers: kafka.broker.id, kafka.cluster.id
+ * - for connect workers: connect.kafka.cluster.id, connect.group.id
+ */
+@InterfaceStability.Evolving
+public interface MetricsContext {
Review comment:
I wasn't suggesting that we eliminate the interface, I definitely think
having one is a good choice (for the reasons you mentioned). What I meant was
in this interface, we expose a Map as the collection of metrics tags/labels.
But since it appears that the usage is intended to be read-only, maybe a Map
isn't the best choice. Here's what I was thinking:
```java
interface MetricsContext {
String namespace();
String get(String field);
Collection<String> fields();
}
```
(included the namespace suggestion from my other comment as well).
##########
File path:
clients/src/main/java/org/apache/kafka/common/metrics/MetricsContext.java
##########
@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.metrics;
+
+import org.apache.kafka.common.annotation.InterfaceStability;
+
+import java.util.Map;
+
+/**
+ * MetricsContext encapsulates additional metadata about metrics exposed via a
+ * {@link org.apache.kafka.common.metrics.MetricsReporter}
+ *
+ * The metadata map provides following information:
+ * - a <code>_namespace</node> field indicating the component exposing metrics
+ * e.g. kafka.server, kafka.consumer
+ * {@link JmxReporter} uses this as prefix for mbean names
+ *
+ * - for clients and streams libraries: any freeform fields passed in via
+ * client properties in the form of `metrics.context.<key>=<value>
+ *
+ * - for kafka brokers: kafka.broker.id, kafka.cluster.id
+ * - for connect workers: connect.kafka.cluster.id, connect.group.id
+ */
+@InterfaceStability.Evolving
+public interface MetricsContext {
+ /* predefined fields */
+ String NAMESPACE = "_namespace"; // metrics namespace, formerly jmx prefix
Review comment:
Sorry, I shouldn't have said "field" since that implies a concrete
class. See above comment above for an example of what I meant.
##########
File path:
clients/src/main/java/org/apache/kafka/common/metrics/JmxReporter.java
##########
@@ -71,8 +72,13 @@ public JmxReporter() {
/**
* Create a JMX reporter that prefixes all metrics with the given string.
+ * @deprecated Since 2.6.0. Use {@link JmxReporter#JmxReporter()}
+ * Initialize JmxReporter with {@link
JmxReporter#contextChange(MetricsContext)}
+ * Populate prefix by adding _namespace/prefix key value pair to {@link
MetricsContext}
*/
+ @Deprecated
Review comment:
Sounds good, thanks 👍
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