kl0u commented on a change in pull request #13678:
URL: https://github.com/apache/flink/pull/13678#discussion_r508475873



##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/AbstractStreamingCommitterOperator.java
##########
@@ -0,0 +1,179 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import 
org.apache.flink.api.common.typeutils.base.array.BytePrimitiveArraySerializer;
+import org.apache.flink.api.connector.sink.Committer;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.runtime.state.StateInitializationContext;
+import org.apache.flink.runtime.state.StateSnapshotContext;
+import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
+import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
+import org.apache.flink.streaming.api.operators.util.SimpleVersionedListState;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Abstract base class for operators that work with a {@link Committer} or a
+ * {@link org.apache.flink.api.connector.sink.GlobalCommitter} in the 
streaming execution mode.
+ *
+ * <p>Sub-classes are responsible for implementing {@link 
#recoveredCommittables(List)} and {@link #preCommit(List)}.
+ *
+ * @param <InputT> The input type of the {@link Committer}.
+ * @param <CommT> The committable type of the {@link Committer}.
+ */
+abstract class AbstractStreamingCommitterOperator<InputT, CommT> extends 
AbstractStreamOperator<CommT>
+               implements OneInputStreamOperator<InputT, CommT> {
+
+       private static final long serialVersionUID = 1L;
+
+       /** The operator's state descriptor. */
+       private static final ListStateDescriptor<byte[]> 
STREAMING_COMMITTER_RAW_STATES_DESC =
+                       new ListStateDescriptor<>(
+                                       "streaming_committer_raw_states",
+                                       BytePrimitiveArraySerializer.INSTANCE);
+
+       /** Group the committable by the checkpoint id. */
+       private final NavigableMap<Long, List<CommT>> committablesPerCheckpoint;
+
+       /** The committable's serializer. */
+       private final StreamingCommitterStateSerializer<CommT> 
streamingCommitterStateSerializer;
+
+       /** Responsible for committing the committable to the external system. 
**/
+       protected final Committer<CommT> committer;
+
+       /** The operator's state. */
+       private ListState<StreamingCommitterState<CommT>> 
streamingCommitterState;
+
+       /** Inputs collected between every pre-commit. */
+       private List<InputT> currentInputs;
+
+       /**
+        * Notifies a list of committables that might need to be committed 
again after recovering from a failover.
+        *
+        * @param committables A list of committables
+        */
+       abstract void recoveredCommittables(List<CommT> committables);
+
+       /**
+        * Prepares a commit.
+        *
+        * @param input A list of input elements received since last pre-commit
+        *
+        * @return @return A list of committables that could be committed in 
the following checkpoint complete.
+        */
+       abstract List<CommT> preCommit(List<InputT> input);
+
+       AbstractStreamingCommitterOperator(
+                       Committer<CommT> committer,
+                       SimpleVersionedSerializer<CommT> committableSerializer) 
{
+               this.committer = checkNotNull(committer);
+               this.streamingCommitterStateSerializer = new 
StreamingCommitterStateSerializer<>(
+                               checkNotNull(committableSerializer));
+               this.committablesPerCheckpoint = new TreeMap<>();
+               this.currentInputs = new ArrayList<>();
+       }
+
+       @Override
+       public void initializeState(StateInitializationContext context) throws 
Exception {
+               super.initializeState(context);
+               streamingCommitterState = new SimpleVersionedListState<>(
+                               
context.getOperatorStateStore().getListState(STREAMING_COMMITTER_RAW_STATES_DESC),
+                               streamingCommitterStateSerializer);
+               final List<CommT> restored = new ArrayList<>();
+               streamingCommitterState.get().forEach(s -> 
restored.addAll(s.getCommittables()));
+               recoveredCommittables(restored);
+       }
+
+       @Override
+       public void processElement(StreamRecord<InputT> element) throws 
Exception {
+               currentInputs.add(element.getValue());
+       }
+
+       @Override
+       public void close() throws Exception {
+               super.close();
+               committer.close();
+       }
+
+       @Override
+       public void snapshotState(StateSnapshotContext context) throws 
Exception {
+               super.snapshotState(context);
+               committablesPerCheckpoint.put(context.getCheckpointId(), 
preCommit(currentInputs));
+               streamingCommitterState.update(
+                               Collections.singletonList(new 
StreamingCommitterState<>(committablesPerCheckpoint)));
+               currentInputs = new ArrayList<>();
+       }
+
+       @Override
+       public void notifyCheckpointComplete(long checkpointId) throws 
Exception {
+               super.notifyCheckpointComplete(checkpointId);
+               commitUpTo(checkpointId);
+       }
+
+       private void commitUpTo(long checkpointId) throws Exception {
+               final Iterator<Map.Entry<Long, List<CommT>>>
+                               it = 
committablesPerCheckpoint.headMap(checkpointId, true).entrySet().iterator();
+
+               while (it.hasNext()) {
+                       final Map.Entry<Long, List<CommT>> entry = it.next();
+                       final List<CommT> neededToRetryCommittables = 
committer.commit(entry.getValue());

Review comment:
       Here we can get the values (`List<CommT> committables = 
entry.getValue();`)  and reuse them, and not call `entry.getValue()` multiple 
times.

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/GlobalStreamingCommitterOperator.java
##########
@@ -0,0 +1,88 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.connector.sink.GlobalCommitter;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.streaming.api.operators.BoundedOneInput;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Runtime {@link org.apache.flink.streaming.api.operators.StreamOperator} for 
executing
+ * {@link GlobalCommitter} in the streaming execution mode.
+ *
+ * @param <CommT> The committable type of the {@link GlobalCommitter}.
+ * @param <GlobalCommT> The global committable type of the {@link 
GlobalCommitter}.
+ */
+@Internal
+public final class GlobalStreamingCommitterOperator<CommT, GlobalCommT> 
extends AbstractStreamingCommitterOperator<CommT, GlobalCommT>
+               implements BoundedOneInput {
+
+       /** Aggregate committables to global committables and commit the global 
committables to the external system. */
+       private final GlobalCommitter<CommT, GlobalCommT> globalCommitter;
+
+       /** The global committables that might need to be committed again after 
recovering from a failover. */
+       private List<GlobalCommT> recoveredGlobalCommittables;

Review comment:
       I think the code would be easier if this becomes `final` and we do not 
set it to `null` but we call `clear()` whenever we want to re-initialize it. 
This will remove all the checks about `if (mylist == null) ...`.

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/AbstractStreamingCommitterOperator.java
##########
@@ -0,0 +1,179 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import 
org.apache.flink.api.common.typeutils.base.array.BytePrimitiveArraySerializer;
+import org.apache.flink.api.connector.sink.Committer;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.runtime.state.StateInitializationContext;
+import org.apache.flink.runtime.state.StateSnapshotContext;
+import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
+import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
+import org.apache.flink.streaming.api.operators.util.SimpleVersionedListState;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Abstract base class for operators that work with a {@link Committer} or a
+ * {@link org.apache.flink.api.connector.sink.GlobalCommitter} in the 
streaming execution mode.
+ *
+ * <p>Sub-classes are responsible for implementing {@link 
#recoveredCommittables(List)} and {@link #preCommit(List)}.
+ *
+ * @param <InputT> The input type of the {@link Committer}.
+ * @param <CommT> The committable type of the {@link Committer}.
+ */
+abstract class AbstractStreamingCommitterOperator<InputT, CommT> extends 
AbstractStreamOperator<CommT>
+               implements OneInputStreamOperator<InputT, CommT> {
+
+       private static final long serialVersionUID = 1L;
+
+       /** The operator's state descriptor. */
+       private static final ListStateDescriptor<byte[]> 
STREAMING_COMMITTER_RAW_STATES_DESC =
+                       new ListStateDescriptor<>(
+                                       "streaming_committer_raw_states",
+                                       BytePrimitiveArraySerializer.INSTANCE);
+
+       /** Group the committable by the checkpoint id. */
+       private final NavigableMap<Long, List<CommT>> committablesPerCheckpoint;
+
+       /** The committable's serializer. */
+       private final StreamingCommitterStateSerializer<CommT> 
streamingCommitterStateSerializer;
+
+       /** Responsible for committing the committable to the external system. 
**/
+       protected final Committer<CommT> committer;

Review comment:
       I would propose to make this `private` and add a getter that is visible 
for testing. In general I am not so much in favour of `@VisibleForTesting` 
things and I would prefer if we passed a custom `Committer` in the test harness 
and use that to get whatever internal information we want, but I understand 
that this may require refactoring the tests which may take some time. 
   
   But that can be a thing to keep it in the list of future things to do :)

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/StreamingCommitterOperator.java
##########
@@ -0,0 +1,60 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.api.connector.sink.Committer;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Runtime {@link org.apache.flink.streaming.api.operators.StreamOperator} for 
executing
+ * {@link Committer} in the streaming execution mode.
+ *
+ * @param <CommT> The committable type of the {@link Committer}.
+ */
+final class StreamingCommitterOperator<CommT> extends 
AbstractStreamingCommitterOperator<CommT, CommT> {
+
+       /** The committables that might need to be committed again after 
recovering from a failover. */
+       private List<CommT> recoveredCommittables;

Review comment:
       As in the global committer, I would make this `final` and simply clear 
it up whenever we want to re-initialize it. I think that checking for `null` 
always leaves a possibility for error in the future, when someone else will 
touch this code.

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/AbstractStreamingCommitterOperator.java
##########
@@ -0,0 +1,179 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import 
org.apache.flink.api.common.typeutils.base.array.BytePrimitiveArraySerializer;
+import org.apache.flink.api.connector.sink.Committer;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.runtime.state.StateInitializationContext;
+import org.apache.flink.runtime.state.StateSnapshotContext;
+import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
+import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
+import org.apache.flink.streaming.api.operators.util.SimpleVersionedListState;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Abstract base class for operators that work with a {@link Committer} or a
+ * {@link org.apache.flink.api.connector.sink.GlobalCommitter} in the 
streaming execution mode.
+ *
+ * <p>Sub-classes are responsible for implementing {@link 
#recoveredCommittables(List)} and {@link #preCommit(List)}.
+ *
+ * @param <InputT> The input type of the {@link Committer}.
+ * @param <CommT> The committable type of the {@link Committer}.
+ */
+abstract class AbstractStreamingCommitterOperator<InputT, CommT> extends 
AbstractStreamOperator<CommT>
+               implements OneInputStreamOperator<InputT, CommT> {
+
+       private static final long serialVersionUID = 1L;
+
+       /** The operator's state descriptor. */
+       private static final ListStateDescriptor<byte[]> 
STREAMING_COMMITTER_RAW_STATES_DESC =
+                       new ListStateDescriptor<>(
+                                       "streaming_committer_raw_states",
+                                       BytePrimitiveArraySerializer.INSTANCE);
+
+       /** Group the committable by the checkpoint id. */
+       private final NavigableMap<Long, List<CommT>> committablesPerCheckpoint;
+
+       /** The committable's serializer. */
+       private final StreamingCommitterStateSerializer<CommT> 
streamingCommitterStateSerializer;
+
+       /** Responsible for committing the committable to the external system. 
**/
+       protected final Committer<CommT> committer;
+
+       /** The operator's state. */
+       private ListState<StreamingCommitterState<CommT>> 
streamingCommitterState;
+
+       /** Inputs collected between every pre-commit. */
+       private List<InputT> currentInputs;
+
+       /**
+        * Notifies a list of committables that might need to be committed 
again after recovering from a failover.
+        *
+        * @param committables A list of committables
+        */
+       abstract void recoveredCommittables(List<CommT> committables);
+
+       /**
+        * Prepares a commit.
+        *
+        * @param input A list of input elements received since last pre-commit
+        *
+        * @return @return A list of committables that could be committed in 
the following checkpoint complete.
+        */
+       abstract List<CommT> preCommit(List<InputT> input);
+
+       AbstractStreamingCommitterOperator(
+                       Committer<CommT> committer,
+                       SimpleVersionedSerializer<CommT> committableSerializer) 
{
+               this.committer = checkNotNull(committer);
+               this.streamingCommitterStateSerializer = new 
StreamingCommitterStateSerializer<>(
+                               checkNotNull(committableSerializer));

Review comment:
       We do not need `checkNotNull` here because we check in the 
`StreamingCommitterStateSerializer` constructor.

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/GlobalStreamingCommitterOperator.java
##########
@@ -0,0 +1,88 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.connector.sink.GlobalCommitter;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.streaming.api.operators.BoundedOneInput;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Runtime {@link org.apache.flink.streaming.api.operators.StreamOperator} for 
executing
+ * {@link GlobalCommitter} in the streaming execution mode.
+ *
+ * @param <CommT> The committable type of the {@link GlobalCommitter}.
+ * @param <GlobalCommT> The global committable type of the {@link 
GlobalCommitter}.
+ */
+@Internal
+public final class GlobalStreamingCommitterOperator<CommT, GlobalCommT> 
extends AbstractStreamingCommitterOperator<CommT, GlobalCommT>
+               implements BoundedOneInput {
+
+       /** Aggregate committables to global committables and commit the global 
committables to the external system. */
+       private final GlobalCommitter<CommT, GlobalCommT> globalCommitter;
+
+       /** The global committables that might need to be committed again after 
recovering from a failover. */
+       private List<GlobalCommT> recoveredGlobalCommittables;
+
+       private boolean endOfInput;
+
+       GlobalStreamingCommitterOperator(
+                       GlobalCommitter<CommT, GlobalCommT> globalCommitter,
+                       SimpleVersionedSerializer<GlobalCommT> 
committableSerializer) {
+               super(globalCommitter, committableSerializer);
+               this.globalCommitter = checkNotNull(globalCommitter);
+               this.endOfInput = false;
+       }
+
+       @Override
+       void recoveredCommittables(List<GlobalCommT> committables) {
+               recoveredGlobalCommittables = 
globalCommitter.filterRecoveredCommittables(committables);
+       }
+
+       @Override
+       List<GlobalCommT> preCommit(List<CommT> input) {
+               final List<GlobalCommT> result = new ArrayList<>();
+               if (recoveredGlobalCommittables != null && 
!recoveredGlobalCommittables.isEmpty()) {

Review comment:
       With the above changes, this can become :
   
   ```
   final List<GlobalCommT> result =
                                new ArrayList<>(recoveredGlobalCommittables);
   recoveredGlobalCommittables.clear();
   
   if (!input.isEmpty()) {
        result.add(globalCommitter.combine(input));
   }
   ```

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/AbstractStreamingCommitterOperator.java
##########
@@ -0,0 +1,179 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import 
org.apache.flink.api.common.typeutils.base.array.BytePrimitiveArraySerializer;
+import org.apache.flink.api.connector.sink.Committer;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.runtime.state.StateInitializationContext;
+import org.apache.flink.runtime.state.StateSnapshotContext;
+import org.apache.flink.streaming.api.operators.AbstractStreamOperator;
+import org.apache.flink.streaming.api.operators.OneInputStreamOperator;
+import org.apache.flink.streaming.api.operators.util.SimpleVersionedListState;
+import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Abstract base class for operators that work with a {@link Committer} or a
+ * {@link org.apache.flink.api.connector.sink.GlobalCommitter} in the 
streaming execution mode.
+ *
+ * <p>Sub-classes are responsible for implementing {@link 
#recoveredCommittables(List)} and {@link #preCommit(List)}.
+ *
+ * @param <InputT> The input type of the {@link Committer}.
+ * @param <CommT> The committable type of the {@link Committer}.
+ */
+abstract class AbstractStreamingCommitterOperator<InputT, CommT> extends 
AbstractStreamOperator<CommT>
+               implements OneInputStreamOperator<InputT, CommT> {
+
+       private static final long serialVersionUID = 1L;
+
+       /** The operator's state descriptor. */
+       private static final ListStateDescriptor<byte[]> 
STREAMING_COMMITTER_RAW_STATES_DESC =
+                       new ListStateDescriptor<>(
+                                       "streaming_committer_raw_states",
+                                       BytePrimitiveArraySerializer.INSTANCE);
+
+       /** Group the committable by the checkpoint id. */
+       private final NavigableMap<Long, List<CommT>> committablesPerCheckpoint;
+
+       /** The committable's serializer. */
+       private final StreamingCommitterStateSerializer<CommT> 
streamingCommitterStateSerializer;
+
+       /** Responsible for committing the committable to the external system. 
**/
+       protected final Committer<CommT> committer;
+
+       /** The operator's state. */
+       private ListState<StreamingCommitterState<CommT>> 
streamingCommitterState;
+
+       /** Inputs collected between every pre-commit. */
+       private List<InputT> currentInputs;
+
+       /**
+        * Notifies a list of committables that might need to be committed 
again after recovering from a failover.
+        *
+        * @param committables A list of committables
+        */
+       abstract void recoveredCommittables(List<CommT> committables);
+
+       /**
+        * Prepares a commit.
+        *
+        * @param input A list of input elements received since last pre-commit
+        *
+        * @return @return A list of committables that could be committed in 
the following checkpoint complete.
+        */
+       abstract List<CommT> preCommit(List<InputT> input);
+
+       AbstractStreamingCommitterOperator(
+                       Committer<CommT> committer,
+                       SimpleVersionedSerializer<CommT> committableSerializer) 
{
+               this.committer = checkNotNull(committer);
+               this.streamingCommitterStateSerializer = new 
StreamingCommitterStateSerializer<>(
+                               checkNotNull(committableSerializer));
+               this.committablesPerCheckpoint = new TreeMap<>();
+               this.currentInputs = new ArrayList<>();
+       }
+
+       @Override
+       public void initializeState(StateInitializationContext context) throws 
Exception {
+               super.initializeState(context);
+               streamingCommitterState = new SimpleVersionedListState<>(
+                               
context.getOperatorStateStore().getListState(STREAMING_COMMITTER_RAW_STATES_DESC),
+                               streamingCommitterStateSerializer);
+               final List<CommT> restored = new ArrayList<>();
+               streamingCommitterState.get().forEach(s -> 
restored.addAll(s.getCommittables()));
+               recoveredCommittables(restored);
+       }
+
+       @Override
+       public void processElement(StreamRecord<InputT> element) throws 
Exception {
+               currentInputs.add(element.getValue());
+       }
+
+       @Override
+       public void close() throws Exception {
+               super.close();
+               committer.close();
+       }
+
+       @Override
+       public void snapshotState(StateSnapshotContext context) throws 
Exception {
+               super.snapshotState(context);
+               committablesPerCheckpoint.put(context.getCheckpointId(), 
preCommit(currentInputs));
+               streamingCommitterState.update(
+                               Collections.singletonList(new 
StreamingCommitterState<>(committablesPerCheckpoint)));
+               currentInputs = new ArrayList<>();
+       }
+
+       @Override
+       public void notifyCheckpointComplete(long checkpointId) throws 
Exception {
+               super.notifyCheckpointComplete(checkpointId);
+               commitUpTo(checkpointId);
+       }
+
+       private void commitUpTo(long checkpointId) throws Exception {
+               final Iterator<Map.Entry<Long, List<CommT>>>
+                               it = 
committablesPerCheckpoint.headMap(checkpointId, true).entrySet().iterator();
+
+               while (it.hasNext()) {
+                       final Map.Entry<Long, List<CommT>> entry = it.next();
+                       final List<CommT> neededToRetryCommittables = 
committer.commit(entry.getValue());
+
+                       if (!neededToRetryCommittables.isEmpty()) {
+                               throw new 
UnsupportedOperationException("Currently does not support the re-commit!");
+                       }
+

Review comment:
       What about logging here that we are `committing state for checkpoint 
XXXX`. This may help if something goes wrong.

##########
File path: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/sink/GlobalStreamingCommitterOperator.java
##########
@@ -0,0 +1,88 @@
+/*
+ * 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.flink.streaming.runtime.operators.sink;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.connector.sink.GlobalCommitter;
+import org.apache.flink.core.io.SimpleVersionedSerializer;
+import org.apache.flink.streaming.api.operators.BoundedOneInput;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Runtime {@link org.apache.flink.streaming.api.operators.StreamOperator} for 
executing
+ * {@link GlobalCommitter} in the streaming execution mode.
+ *
+ * @param <CommT> The committable type of the {@link GlobalCommitter}.
+ * @param <GlobalCommT> The global committable type of the {@link 
GlobalCommitter}.
+ */
+@Internal
+public final class GlobalStreamingCommitterOperator<CommT, GlobalCommT> 
extends AbstractStreamingCommitterOperator<CommT, GlobalCommT>
+               implements BoundedOneInput {
+
+       /** Aggregate committables to global committables and commit the global 
committables to the external system. */
+       private final GlobalCommitter<CommT, GlobalCommT> globalCommitter;
+
+       /** The global committables that might need to be committed again after 
recovering from a failover. */
+       private List<GlobalCommT> recoveredGlobalCommittables;
+
+       private boolean endOfInput;
+
+       GlobalStreamingCommitterOperator(
+                       GlobalCommitter<CommT, GlobalCommT> globalCommitter,
+                       SimpleVersionedSerializer<GlobalCommT> 
committableSerializer) {
+               super(globalCommitter, committableSerializer);
+               this.globalCommitter = checkNotNull(globalCommitter);
+               this.endOfInput = false;
+       }
+
+       @Override
+       void recoveredCommittables(List<GlobalCommT> committables) {
+               recoveredGlobalCommittables = 
globalCommitter.filterRecoveredCommittables(committables);

Review comment:
       Here we should check that committbles are not `null` to be safe. In 
addition, I would propose to not reuse the same list that we expose to the 
users but we copy the result of the `filterRecoveredCommittables()` in our own 
list.




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