jolshan commented on code in PR #15685:
URL: https://github.com/apache/kafka/pull/15685#discussion_r1618016824
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server-common/src/main/java/org/apache/kafka/server/common/Features.java:
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@@ -16,72 +16,134 @@
*/
package org.apache.kafka.server.common;
-import java.util.Collections;
-import java.util.HashMap;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
import java.util.Map;
-import java.util.Objects;
+import java.util.stream.Collectors;
-import static org.apache.kafka.server.common.MetadataVersion.FEATURE_NAME;
+/**
+ * This is enum for the various features implemented for Kafka clusters.
+ * KIP-584: Versioning Scheme for Features introduced the idea of various
features, but only added one feature -- MetadataVersion.
+ * KIP-1022: Formatting and Updating Features allowed for more features to be
added. In order to set and update features,
+ * they need to be specified via the StorageTool or FeatureCommand tools.
+ * <br>
+ * Having a unified enum for the features that will use a shared type in the
API used to set and update them
+ * makes it easier to process these features.
+ */
+public enum Features {
+
+ /**
+ * Features defined. If a feature is included in this list, and marked to
be used in production they will also be specified when
+ * formatting a cluster via the StorageTool. MetadataVersion is handled
separately, so it is not included here.
+ *
+ * See {@link TestFeatureVersion} as an example. See {@link
FeatureVersion} when implementing a new feature.
+ */
+ TEST_VERSION("test.feature.version", TestFeatureVersion.values());
+
+ public static final Features[] FEATURES;
+ public static final List<Features> PRODUCTION_FEATURES;
-public final class Features {
- private final MetadataVersion version;
- private final Map<String, Short> finalizedFeatures;
- private final long finalizedFeaturesEpoch;
+ public static final List<String> PRODUCTION_FEATURE_NAMES;
+ private final String name;
+ private final FeatureVersion[] featureVersions;
- public static Features fromKRaftVersion(MetadataVersion version) {
- return new Features(version, Collections.emptyMap(), -1, true);
+ Features(String name,
+ FeatureVersion[] featureVersions) {
+ this.name = name;
+ this.featureVersions = featureVersions;
}
- public Features(
- MetadataVersion version,
- Map<String, Short> finalizedFeatures,
- long finalizedFeaturesEpoch,
- boolean kraftMode
- ) {
- this.version = version;
- this.finalizedFeatures = new HashMap<>(finalizedFeatures);
- this.finalizedFeaturesEpoch = finalizedFeaturesEpoch;
- // In KRaft mode, we always include the metadata version in the
features map.
- // In ZK mode, we never include it.
- if (kraftMode) {
- this.finalizedFeatures.put(FEATURE_NAME, version.featureLevel());
- } else {
- this.finalizedFeatures.remove(FEATURE_NAME);
- }
+ static {
+ Features[] enumValues = Features.values();
+ FEATURES = Arrays.copyOf(enumValues, enumValues.length);
+
+ PRODUCTION_FEATURES = Arrays.stream(FEATURES).filter(feature ->
+ feature.name !=
TEST_VERSION.featureName()).collect(Collectors.toList());
+ PRODUCTION_FEATURE_NAMES = PRODUCTION_FEATURES.stream().map(feature ->
+ feature.name).collect(Collectors.toList());
}
- public MetadataVersion metadataVersion() {
- return version;
+ public String featureName() {
+ return name;
}
- public Map<String, Short> finalizedFeatures() {
- return finalizedFeatures;
+ public FeatureVersion[] featureVersions() {
+ return featureVersions;
}
- public long finalizedFeaturesEpoch() {
- return finalizedFeaturesEpoch;
+ public short latestProduction() {
+ return defaultValue(MetadataVersion.LATEST_PRODUCTION);
}
- @Override
- public boolean equals(Object o) {
- if (o == null || !(o.getClass().equals(Features.class))) return false;
- Features other = (Features) o;
- return version == other.version &&
- finalizedFeatures.equals(other.finalizedFeatures) &&
- finalizedFeaturesEpoch == other.finalizedFeaturesEpoch;
+ /**
+ * Creates a FeatureVersion from a level.
+ *
+ * @param level the level of the feature
+ * @return the FeatureVersionUtils.FeatureVersion for the feature
the enum is based on.
+ * @throws IllegalArgumentException if the feature is not known.
+ */
+ public FeatureVersion fromFeatureLevel(short level) {
+ return Arrays.stream(featureVersions).filter(featureVersion ->
+ featureVersion.featureLevel() == level).findFirst().orElseThrow(
+ () -> new IllegalArgumentException("No feature:" +
featureName() + " with feature level " + level));
}
- @Override
- public int hashCode() {
- return Objects.hash(version, finalizedFeatures,
finalizedFeaturesEpoch);
+ /**
+ * A method to validate the feature can be set. If a given feature relies
on another feature, the dependencies should be
+ * captured in {@link FeatureVersion#dependencies()}
+ * <p>
+ * For example, say feature X level x relies on feature Y level y:
+ * if feature X >= x then throw an error if feature Y < y.
+ *
+ * All feature levels above 0 require metadata.version=4 (IBP_3_3_IV0) in
order to write the feature records to the cluster.
+ *
+ * @param feature the feature we are validating
+ * @param metadataVersion the metadata version we have (or want
to set)
+ * @param features the feature versions (besides
MetadataVersion) we have (or want to set)
+ * @throws IllegalArgumentException if the feature is not valid
+ */
+ public static void validateVersion(FeatureVersion feature, MetadataVersion
metadataVersion, Map<String, Short> features) {
+ if (feature.featureLevel() >= 1 &&
metadataVersion.isLessThan(MetadataVersion.IBP_3_3_IV0))
+ throw new IllegalArgumentException(feature.featureName() + " could
not be set to " + feature.featureLevel() +
+ " because it depends on metadata.version=4 (" +
MetadataVersion.IBP_3_3_IV0 + ")");
+
+ for (Map.Entry<String, Short> dependency:
feature.dependencies().entrySet()) {
+ Short featureLevel = features.get(dependency.getKey());
+
+ if (featureLevel == null || featureLevel < dependency.getValue()) {
+ throw new IllegalArgumentException(feature.featureName() + "
could not be set to " + feature.featureLevel() +
+ " because it depends on " + dependency.getKey() + "
level " + dependency.getValue());
+ }
+ }
+ }
+
+ /**
+ * A method to return the default (latest production) level of a feature
based on the metadata version provided.
+ *
+ * Every time a new feature is added, it should create a mapping from
metadata version to feature version
+ * with {@link FeatureVersion#bootstrapMetadataVersion()}. When the
feature version is production ready, the metadata
+ * version should be made production ready as well.
+ *
+ * @param metadataVersion the metadata version we want to use to set the
default.
+ * @return the default version level for the feature and potential
metadata version
Review Comment:
I was meaning given the input of MV. I can clarify this since it is
confusing.
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