dawidwys commented on a change in pull request #13853:
URL: https://github.com/apache/flink/pull/13853#discussion_r517412480
##########
File path:
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/TimestampsAndWatermarksOperator.java
##########
@@ -83,12 +81,14 @@ public void open() throws Exception {
super.open();
timestampAssigner =
watermarkStrategy.createTimestampAssigner(this::getMetricGroup);
- watermarkGenerator =
watermarkStrategy.createWatermarkGenerator(this::getMetricGroup);
+ watermarkGenerator = new NoOpWatermarkGenerator<>(
+
watermarkStrategy.createWatermarkGenerator(this::getMetricGroup),
+ emitProgressiveWatermarks);
wmOutput = new WatermarkEmitter(output,
getContainingTask().getStreamStatusMaintainer());
watermarkInterval =
getExecutionConfig().getAutoWatermarkInterval();
- if (watermarkInterval > 0 && emitProgressiveWatermarks) {
+ if (watermarkInterval > 0) {
Review comment:
This check was valid as we do not want to register timers, if we don't
need to.
##########
File path:
flink-core/src/main/java/org/apache/flink/api/common/eventtime/NoOpWatermarkGenerator.java
##########
@@ -0,0 +1,63 @@
+/*
+ * 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.api.common.eventtime;
+
+import org.apache.flink.annotation.Public;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * An implementation of a {@link WatermarkGenerator} that periodically emits
watermarks
+ * or generates only one final watermark at the end of input.
+ */
+@Public
+public final class NoOpWatermarkGenerator<E> implements WatermarkGenerator<E> {
Review comment:
I would make it a private class in the
`TimestampsAndWatermarksOperator`. Certainly it should not be a `@Public` class.
Moreover I thought we should rather have a class like:
```
/**
* An implementation of a {@link WatermarkGenerator} that does not emit
watermarks.
*/
public final class NoOpWatermarkGenerator<E> implements
WatermarkGenerator<E> {
@Override
public void onEvent(E event, long eventTimestamp, WatermarkOutput
output) {
}
@Override
public void onPeriodicEmit(WatermarkOutput output) {
}
}
```
##########
File path:
flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/TimestampsAndWatermarksOperator.java
##########
@@ -83,12 +81,14 @@ public void open() throws Exception {
super.open();
timestampAssigner =
watermarkStrategy.createTimestampAssigner(this::getMetricGroup);
- watermarkGenerator =
watermarkStrategy.createWatermarkGenerator(this::getMetricGroup);
+ watermarkGenerator = new NoOpWatermarkGenerator<>(
Review comment:
Here I would do:
```
if (emitProgressiveWatermarks) {
watermarkGenerator =
watermarkStrategy.createWatermarkGenerator(this::getMetricGroup);
} else {
watermarkGenerator = new NoOpWatermarkGenerator();
}
```
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