kowshik commented on a change in pull request #9001:
URL: https://github.com/apache/kafka/pull/9001#discussion_r468089357
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File path: core/src/main/scala/kafka/controller/KafkaController.scala
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@@ -266,6 +275,199 @@ class KafkaController(val config: KafkaConfig,
}
}
+ private def createFeatureZNode(newNode: FeatureZNode): Int = {
+ info(s"Creating FeatureZNode at path: ${FeatureZNode.path} with contents:
$newNode")
+ zkClient.createFeatureZNode(newNode)
+ val (_, newVersion) = zkClient.getDataAndVersion(FeatureZNode.path)
+ newVersion
+ }
+
+ private def updateFeatureZNode(updatedNode: FeatureZNode): Int = {
+ info(s"Updating FeatureZNode at path: ${FeatureZNode.path} with contents:
$updatedNode")
+ zkClient.updateFeatureZNode(updatedNode)
+ }
+
+ /**
+ * This method enables the feature versioning system (KIP-584).
+ *
+ * Development in Kafka (from a high level) is organized into features. Each
feature is tracked by
+ * a name and a range of version numbers. A feature can be of two types:
+ *
+ * 1. Supported feature:
+ * A supported feature is represented by a name (String) and a range of
versions (defined by a
+ * {@link SupportedVersionRange}). It refers to a feature that a particular
broker advertises
+ * support for. Each broker advertises the version ranges of its own
supported features in its
+ * own BrokerIdZNode. The contents of the advertisement are specific to the
particular broker and
+ * do not represent any guarantee of a cluster-wide availability of the
feature for any particular
+ * range of versions.
+ *
+ * 2. Finalized feature:
+ * A finalized feature is represented by a name (String) and a range of
version levels (defined
+ * by a {@link FinalizedVersionRange}). Whenever the feature versioning
system (KIP-584) is
+ * enabled, the finalized features are stored in the cluster-wide common
FeatureZNode.
+ * In comparison to a supported feature, the key difference is that a
finalized feature exists
+ * in ZK only when it is guaranteed to be supported by any random broker in
the cluster for a
+ * specified range of version levels. Also, the controller is the only
entity modifying the
+ * information about finalized features.
+ *
+ * This method sets up the FeatureZNode with enabled status, which means
that the finalized
+ * features stored in the FeatureZNode are active. The enabled status should
be written by the
+ * controller to the FeatureZNode only when the broker IBP config is greater
than or equal to
+ * KAFKA_2_7_IV0.
Review comment:
To be sure we are on same page, is this because of a controller failover
during an IBP bump?
It seems to me that this can happen mainly when IBP is being bumped from a
value less than KAFKA_2_7_IV0 to a value greater than or equal to KAFKA_2_7_IV0
(assuming subsequent IBP bumps will be from KAFKA_2_7_IV0 to a higher value, so
the node status will remain enabled).
In general, I'm not sure how to avoid this node status flip until IBP bump
has been completed cluster-wide.
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