Re: [PR] KAFKA-17367: Share coordinator impl. Broker side code. [2/N] [kafka]

["chia7712 (via GitHub)" <gi...@apache.org>]

chia7712 commented on code in PR #17011:
URL: https://github.com/apache/kafka/pull/17011#discussion_r2680952783


##########
share-coordinator/src/main/java/org/apache/kafka/coordinator/share/ShareCoordinatorShard.java:
##########
@@ -17,58 +17,565 @@
 
 package org.apache.kafka.coordinator.share;
 
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.Uuid;
 import org.apache.kafka.common.message.ReadShareGroupStateRequestData;
 import org.apache.kafka.common.message.ReadShareGroupStateResponseData;
 import org.apache.kafka.common.message.WriteShareGroupStateRequestData;
 import org.apache.kafka.common.message.WriteShareGroupStateResponseData;
-import org.apache.kafka.common.requests.RequestContext;
+import org.apache.kafka.common.protocol.ApiMessage;
+import org.apache.kafka.common.protocol.Errors;
+import org.apache.kafka.common.requests.ReadShareGroupStateResponse;
 import org.apache.kafka.common.requests.TransactionResult;
+import org.apache.kafka.common.requests.WriteShareGroupStateResponse;
+import org.apache.kafka.common.utils.LogContext;
+import org.apache.kafka.common.utils.Time;
+import org.apache.kafka.coordinator.common.runtime.CoordinatorMetrics;
+import org.apache.kafka.coordinator.common.runtime.CoordinatorMetricsShard;
 import org.apache.kafka.coordinator.common.runtime.CoordinatorRecord;
 import org.apache.kafka.coordinator.common.runtime.CoordinatorResult;
 import org.apache.kafka.coordinator.common.runtime.CoordinatorShard;
+import org.apache.kafka.coordinator.common.runtime.CoordinatorShardBuilder;
+import org.apache.kafka.coordinator.common.runtime.CoordinatorTimer;
+import org.apache.kafka.coordinator.share.generated.ShareSnapshotKey;
+import org.apache.kafka.coordinator.share.generated.ShareSnapshotValue;
+import org.apache.kafka.coordinator.share.generated.ShareUpdateKey;
+import org.apache.kafka.coordinator.share.generated.ShareUpdateValue;
+import org.apache.kafka.coordinator.share.metrics.ShareCoordinatorMetrics;
+import org.apache.kafka.coordinator.share.metrics.ShareCoordinatorMetricsShard;
 import org.apache.kafka.image.MetadataDelta;
 import org.apache.kafka.image.MetadataImage;
+import org.apache.kafka.server.common.ApiMessageAndVersion;
+import org.apache.kafka.server.config.ShareCoordinatorConfig;
+import org.apache.kafka.server.group.share.PartitionFactory;
+import org.apache.kafka.server.group.share.SharePartitionKey;
+import org.apache.kafka.timeline.SnapshotRegistry;
+import org.apache.kafka.timeline.TimelineHashMap;
+
+import org.slf4j.Logger;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
 
-/**
- * The share coordinator shard is a replicated state machine that manages the metadata of all
- * share partitions. It holds the hard and the soft state of the share partitions. This class
- * has two kinds of methods:
- * 1) The request handlers which handle the requests and generate a response and records to
- *    mutate the hard state. Those records will be written by the runtime and applied to the
- *    hard state via the replay methods.
- * 2) The replay methods which apply records to the hard state. Those are used in the request
- *    handling as well as during the initial loading of the records from the partitions.
- */
 public class ShareCoordinatorShard implements CoordinatorShard<CoordinatorRecord> {
+    private final Logger log;
+    private final ShareCoordinatorConfig config;
+    private final CoordinatorMetrics coordinatorMetrics;
+    private final CoordinatorMetricsShard metricsShard;
+    private final TimelineHashMap<SharePartitionKey, ShareGroupOffset> shareStateMap;  // coord key -> ShareGroupOffset
+    // leaderEpochMap can be updated by writeState call
+    // or if a newer leader makes a readState call.
+    private final TimelineHashMap<SharePartitionKey, Integer> leaderEpochMap;
+    private final TimelineHashMap<SharePartitionKey, Integer> snapshotUpdateCount;
+    private final TimelineHashMap<SharePartitionKey, Integer> stateEpochMap;
+    private MetadataImage metadataImage;
+
+    public static final Exception NULL_TOPIC_ID = new Exception("The topic id cannot be null.");
+    public static final Exception NEGATIVE_PARTITION_ID = new Exception("The partition id cannot be a negative number.");
+
+    public static class Builder implements CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> {
+        private ShareCoordinatorConfig config;
+        private LogContext logContext;
+        private SnapshotRegistry snapshotRegistry;
+        private CoordinatorMetrics coordinatorMetrics;
+        private TopicPartition topicPartition;
+
+        public Builder(ShareCoordinatorConfig config) {
+            this.config = config;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withSnapshotRegistry(SnapshotRegistry snapshotRegistry) {
+            this.snapshotRegistry = snapshotRegistry;
+            return this;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withLogContext(LogContext logContext) {
+            this.logContext = logContext;
+            return this;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withTime(Time time) {
+            // method is required due to interface
+            return this;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withTimer(CoordinatorTimer<Void, CoordinatorRecord> timer) {
+            // method is required due to interface
+            return this;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withCoordinatorMetrics(CoordinatorMetrics coordinatorMetrics) {
+            this.coordinatorMetrics = coordinatorMetrics;
+            return this;
+        }
+
+        @Override
+        public CoordinatorShardBuilder<ShareCoordinatorShard, CoordinatorRecord> withTopicPartition(TopicPartition topicPartition) {
+            this.topicPartition = topicPartition;
+            return this;
+        }
+
+        @Override
+        @SuppressWarnings("NPathComplexity")
+        public ShareCoordinatorShard build() {
+            if (logContext == null) logContext = new LogContext();
+            if (config == null)
+                throw new IllegalArgumentException("Config must be set.");
+            if (snapshotRegistry == null)
+                throw new IllegalArgumentException("SnapshotRegistry must be set.");
+            if (coordinatorMetrics == null || !(coordinatorMetrics instanceof ShareCoordinatorMetrics))
+                throw new IllegalArgumentException("CoordinatorMetrics must be set and be of type ShareCoordinatorMetrics.");
+            if (topicPartition == null)
+                throw new IllegalArgumentException("TopicPartition must be set.");
+
+            ShareCoordinatorMetricsShard metricsShard = ((ShareCoordinatorMetrics) coordinatorMetrics)
+                .newMetricsShard(snapshotRegistry, topicPartition);
+
+            return new ShareCoordinatorShard(
+                logContext,
+                config,
+                coordinatorMetrics,
+                metricsShard,
+                snapshotRegistry
+            );
+        }
+    }
+
+    ShareCoordinatorShard(
+        LogContext logContext,
+        ShareCoordinatorConfig config,
+        CoordinatorMetrics coordinatorMetrics,
+        CoordinatorMetricsShard metricsShard,
+        SnapshotRegistry snapshotRegistry
+    ) {
+        this.log = logContext.logger(ShareCoordinatorShard.class);
+        this.config = config;
+        this.coordinatorMetrics = coordinatorMetrics;
+        this.metricsShard = metricsShard;
+        this.shareStateMap = new TimelineHashMap<>(snapshotRegistry, 0);
+        this.leaderEpochMap = new TimelineHashMap<>(snapshotRegistry, 0);
+        this.snapshotUpdateCount = new TimelineHashMap<>(snapshotRegistry, 0);
+        this.stateEpochMap = new TimelineHashMap<>(snapshotRegistry, 0);
+    }
+
     @Override
     public void onLoaded(MetadataImage newImage) {
-        CoordinatorShard.super.onLoaded(newImage);
+        this.metadataImage = newImage;
+        coordinatorMetrics.activateMetricsShard(metricsShard);
     }
 
     @Override
     public void onNewMetadataImage(MetadataImage newImage, MetadataDelta delta) {
-        CoordinatorShard.super.onNewMetadataImage(newImage, delta);
+        this.metadataImage = newImage;
     }
 
     @Override
     public void onUnloaded() {
-        CoordinatorShard.super.onUnloaded();
+        coordinatorMetrics.deactivateMetricsShard(metricsShard);
     }
 
     @Override
     public void replay(long offset, long producerId, short producerEpoch, CoordinatorRecord record) throws RuntimeException {
+        ApiMessageAndVersion key = record.key();
+        ApiMessageAndVersion value = record.value();
+
+        switch (key.version()) {
+            case ShareCoordinator.SHARE_SNAPSHOT_RECORD_KEY_VERSION: // ShareSnapshot
+                handleShareSnapshot((ShareSnapshotKey) key.message(), (ShareSnapshotValue) messageOrNull(value));
+                break;
+            case ShareCoordinator.SHARE_UPDATE_RECORD_KEY_VERSION: // ShareUpdate
+                handleShareUpdate((ShareUpdateKey) key.message(), (ShareUpdateValue) messageOrNull(value));
+                break;
+            default:
+                // noop
+        }
+    }
+
+    private void handleShareSnapshot(ShareSnapshotKey key, ShareSnapshotValue value) {
+        SharePartitionKey mapKey = SharePartitionKey.getInstance(key.groupId(), key.topicId(), key.partition());
+        maybeUpdateLeaderEpochMap(mapKey, value.leaderEpoch());
+        maybeUpdateStateEpochMap(mapKey, value.stateEpoch());
+
+        ShareGroupOffset offsetRecord = ShareGroupOffset.fromRecord(value);
+        // this record is the complete snapshot
+        shareStateMap.put(mapKey, offsetRecord);
+        // if number of share updates is exceeded, then reset it
+        if (snapshotUpdateCount.containsKey(mapKey)) {
+            if (snapshotUpdateCount.get(mapKey) >= config.shareCoordinatorSnapshotUpdateRecordsPerSnapshot()) {
+                snapshotUpdateCount.put(mapKey, 0);
+            }
+        }
+    }
+
+    private void handleShareUpdate(ShareUpdateKey key, ShareUpdateValue value) {
+        SharePartitionKey mapKey = SharePartitionKey.getInstance(key.groupId(), key.topicId(), key.partition());
+        maybeUpdateLeaderEpochMap(mapKey, value.leaderEpoch());
+
+        // share update does not hold state epoch information.
+
+        ShareGroupOffset offsetRecord = ShareGroupOffset.fromRecord(value);
+        // this is an incremental snapshot
+        // so, we need to apply it to our current soft state
+        shareStateMap.compute(mapKey, (k, v) -> v == null ? offsetRecord : merge(v, value));
+        snapshotUpdateCount.compute(mapKey, (k, v) -> v == null ? 0 : v + 1);

Review Comment:
   Since this is the first update, shouldn't the initial value be 1?



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