Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/6062#discussion_r191436243
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/TimerHeapInternalTimer.java
---
@@ -0,0 +1,246 @@
+/*
+ * 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.api.operators;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.common.typeutils.CompatibilityResult;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.common.typeutils.TypeSerializerConfigSnapshot;
+import org.apache.flink.api.common.typeutils.base.LongSerializer;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+
+import java.io.IOException;
+
+/**
+ * Implementation of {@link InternalTimer} for the {@link
InternalTimerHeap}.
+ *
+ * @param <K> Type of the keys to which timers are scoped.
+ * @param <N> Type of the namespace to which timers are scoped.
+ */
+@Internal
+public final class TimerHeapInternalTimer<K, N> implements
InternalTimer<K, N> {
+
+ /** The index that indicates that a tracked internal timer is not
tracked. */
+ private static final int NOT_MANAGED_BY_TIMER_QUEUE_INDEX =
Integer.MIN_VALUE;
+
+ private final long timestamp;
+
+ private final K key;
+
+ private final N namespace;
+
+ /**
+ * This field holds the current physical index of this timer when it is
managed by a timer heap so that we can
+ * support fast deletes.
+ */
+ private transient int timerHeapIndex;
--- End diff --
`TimerHeapInternalTimer` is non serializable. Thus, the `transient` keyword
should not be needed.
---
