stevenzwu commented on a change in pull request #2105: URL: https://github.com/apache/iceberg/pull/2105#discussion_r564074591
########## File path: flink/src/main/java/org/apache/iceberg/flink/source/assigner/SplitAssigner.java ########## @@ -0,0 +1,102 @@ +/* + * 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.iceberg.flink.source.assigner; + +import java.util.Collection; +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import javax.annotation.Nullable; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.flink.source.split.IcebergSourceSplitStatus; + +/** + * Enumerator should call the assigner APIs from the coordinator thread. + * This is to simplify the thread safety for assigner implementation. + */ +public interface SplitAssigner extends AutoCloseable { + + /** + * Some assigners may need to start background threads or perform other activity such as + * registering as listeners to updates from other event sources e.g., watermark tracker. + */ + default void start() { + } + + /** + * Some assigners may need to perform certain actions + * when their corresponding enumerators are closed + */ + @Override + default void close() { + } + + /** + * Request a new split from the assigner + * as enumerator trying to assign splits to awaiting readers + */ + GetSplitResult getNext(@Nullable String hostname); Review comment: that is true. but I am not sure we need to document the enumerator behavior in the assigner interface/contract. Assigner is responsible of returning a split if available. ########## File path: flink/src/main/java/org/apache/iceberg/flink/source/assigner/SplitAssigner.java ########## @@ -0,0 +1,102 @@ +/* + * 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.iceberg.flink.source.assigner; + +import java.util.Collection; +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import javax.annotation.Nullable; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.flink.source.split.IcebergSourceSplitStatus; + +/** + * Enumerator should call the assigner APIs from the coordinator thread. + * This is to simplify the thread safety for assigner implementation. + */ +public interface SplitAssigner extends AutoCloseable { + + /** + * Some assigners may need to start background threads or perform other activity such as + * registering as listeners to updates from other event sources e.g., watermark tracker. + */ + default void start() { + } + + /** + * Some assigners may need to perform certain actions + * when their corresponding enumerators are closed + */ + @Override + default void close() { + } + + /** + * Request a new split from the assigner + * as enumerator trying to assign splits to awaiting readers + */ + GetSplitResult getNext(@Nullable String hostname); + + /** + * Add new splits discovered by enumerator + */ + void onDiscoveredSplits(Collection<IcebergSourceSplit> splits); + + /** + * Forward addSplitsBack event (for failed reader) to assigner + */ + void onUnassignedSplits(Collection<IcebergSourceSplit> splits, int subtaskId); Review comment: I can't think of a use of the subtaskId. I will update both the design doc and APIs. ########## File path: flink/src/main/java/org/apache/iceberg/flink/source/assigner/SplitAssigner.java ########## @@ -0,0 +1,102 @@ +/* + * 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.iceberg.flink.source.assigner; + +import java.util.Collection; +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import javax.annotation.Nullable; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.flink.source.split.IcebergSourceSplitStatus; + +/** + * Enumerator should call the assigner APIs from the coordinator thread. + * This is to simplify the thread safety for assigner implementation. + */ +public interface SplitAssigner extends AutoCloseable { + + /** + * Some assigners may need to start background threads or perform other activity such as + * registering as listeners to updates from other event sources e.g., watermark tracker. + */ + default void start() { + } + + /** + * Some assigners may need to perform certain actions + * when their corresponding enumerators are closed + */ + @Override + default void close() { + } + + /** + * Request a new split from the assigner + * as enumerator trying to assign splits to awaiting readers + */ + GetSplitResult getNext(@Nullable String hostname); + + /** + * Add new splits discovered by enumerator + */ + void onDiscoveredSplits(Collection<IcebergSourceSplit> splits); + + /** + * Forward addSplitsBack event (for failed reader) to assigner + */ + void onUnassignedSplits(Collection<IcebergSourceSplit> splits, int subtaskId); + + /** + * Some assigner (like event time alignment) may rack in-progress splits + * to advance watermark upon completed splits + */ + default void onCompletedSplits(Collection<String> completedSplitIds, int subtaskId) { + } + + /** + * Get assigner state for checkpointing. + * This is a super-set API that works for all currently imagined assigners. + */ + Map<IcebergSourceSplit, IcebergSourceSplitStatus> snapshotState(); Review comment: make sense. will update ########## File path: flink/src/main/java/org/apache/iceberg/flink/source/assigner/SplitAssigner.java ########## @@ -0,0 +1,102 @@ +/* + * 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.iceberg.flink.source.assigner; + +import java.util.Collection; +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import javax.annotation.Nullable; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.flink.source.split.IcebergSourceSplitStatus; + +/** + * Enumerator should call the assigner APIs from the coordinator thread. + * This is to simplify the thread safety for assigner implementation. + */ +public interface SplitAssigner extends AutoCloseable { + + /** + * Some assigners may need to start background threads or perform other activity such as + * registering as listeners to updates from other event sources e.g., watermark tracker. + */ + default void start() { + } + + /** + * Some assigners may need to perform certain actions + * when their corresponding enumerators are closed + */ + @Override + default void close() { + } + + /** + * Request a new split from the assigner + * as enumerator trying to assign splits to awaiting readers + */ + GetSplitResult getNext(@Nullable String hostname); + + /** + * Add new splits discovered by enumerator + */ + void onDiscoveredSplits(Collection<IcebergSourceSplit> splits); + + /** + * Forward addSplitsBack event (for failed reader) to assigner + */ + void onUnassignedSplits(Collection<IcebergSourceSplit> splits, int subtaskId); + + /** + * Some assigner (like event time alignment) may rack in-progress splits + * to advance watermark upon completed splits + */ + default void onCompletedSplits(Collection<String> completedSplitIds, int subtaskId) { + } + + /** + * Get assigner state for checkpointing. + * This is a super-set API that works for all currently imagined assigners. + */ + Map<IcebergSourceSplit, IcebergSourceSplitStatus> snapshotState(); + + /** + * Enumerator can get a notification via CompletableFuture + * when the assigner has more splits available later. + * Enumerator should schedule assignment in the thenAccept action of the future. + * + * Assigner will return the same future if this method is called again + * before the previous future is completed. + * + * The future can be completed from other thread, + * e.g. the coordinator thread from another thread + * for event time alignment. + * + * If enumerator need to trigger action upon the future completion, + * it may want to run it in the coordinator thread + * using {@link SplitEnumeratorContext#runInCoordinatorThread(Runnable)}. + */ + CompletableFuture<Void> isAvailable(); + + /** + * @return assigner stats for monitoring purpose + */ + SplitAssignerStats stats(); Review comment: I was using this poll model of getter on stats, because I was trying to leverage the scheduler service from enumerator to poll the stats. ``` @Override public void start() { assigner.start(); enumeratorContext.callAsync( () -> null, this::updateAssignerStats, enumeratorConfig.metricRefreshInterval().toMillis(), enumeratorConfig.metricRefreshInterval().toMillis()); } ``` We can certainly go with listener model like ``` void subscribeStats(SplitAssignerStatsListener listener); ``` But that won't make difference on those two questions raised - each assigner implementation need to handle the stats logic - add new stat will require change in the listener interface too, right? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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