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https://issues.apache.org/jira/browse/FLINK-9423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16488417#comment-16488417
 ] 

ASF GitHub Bot commented on FLINK-9423:
---------------------------------------

Github user sihuazhou commented on a diff in the pull request:

    https://github.com/apache/flink/pull/6062#discussion_r190463723
  
    --- Diff: 
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/TimerHeapInternalTimer.java
 ---
    @@ -0,0 +1,235 @@
    +/*
    + * 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 if this timer when it is 
managed by a timer heap so that we can
    +    * support fast deletes.
    +    */
    +   private transient int timerHeapIndex;
    +
    +   TimerHeapInternalTimer(long timestamp, K key, N namespace) {
    +           this.timestamp = timestamp;
    +           this.key = key;
    +           this.namespace = namespace;
    +           this.timerHeapIndex = NOT_MANAGED_BY_TIMER_QUEUE_INDEX;
    +   }
    +
    +   @Override
    +   public long getTimestamp() {
    +           return timestamp;
    +   }
    +
    +   @Override
    +   public K getKey() {
    +           return key;
    +   }
    +
    +   @Override
    +   public N getNamespace() {
    +           return namespace;
    +   }
    +
    +   @Override
    +   public boolean equals(Object o) {
    +           if (this == o) {
    +                   return true;
    +           }
    +
    +           if (o instanceof InternalTimer) {
    +                   InternalTimer<?, ?> timer = (InternalTimer<?, ?>) o;
    +                   return timestamp == timer.getTimestamp()
    +                           && key.equals(timer.getKey())
    +                           && namespace.equals(timer.getNamespace());
    +           }
    +
    +           return false;
    +   }
    +
    +   /**
    +    * Returns the current index of this timer in the owning timer heap.
    +    */
    +   int getTimerHeapIndex() {
    +           return timerHeapIndex;
    +   }
    +
    +   /**
    +    * Sets the current index of this timer in the owning timer heap and 
should only be called by the managing heap.
    +    * @param timerHeapIndex the new index in the timer heap.
    +    */
    +   void setTimerHeapIndex(int timerHeapIndex) {
    +           this.timerHeapIndex = timerHeapIndex;
    +   }
    +
    +   /**
    +    * This method can be called to indicate that the timer is no longer 
managed be a timer heap, e.g. because it as
    +    * removed.
    +    */
    +   void removedFromTimerQueue() {
    +           setTimerHeapIndex(NOT_MANAGED_BY_TIMER_QUEUE_INDEX);
    +   }
    +
    +   @Override
    +   public int hashCode() {
    +           int result = (int) (timestamp ^ (timestamp >>> 32));
    +           result = 31 * result + key.hashCode();
    +           result = 31 * result + namespace.hashCode();
    +           return result;
    +   }
    +
    +   @Override
    +   public String toString() {
    +           return "Timer{" +
    +                           "timestamp=" + timestamp +
    +                           ", key=" + key +
    +                           ", namespace=" + namespace +
    +                           '}';
    +   }
    +
    +   /**
    +    * A {@link TypeSerializer} used to serialize/deserialize a {@link 
TimerHeapInternalTimer}.
    +    */
    +   public static class TimerSerializer<K, N> extends 
TypeSerializer<InternalTimer<K, N>> {
    +
    +           private static final long serialVersionUID = 
1119562170939152304L;
    +
    +           private final TypeSerializer<K> keySerializer;
    +
    +           private final TypeSerializer<N> namespaceSerializer;
    +
    +           TimerSerializer(TypeSerializer<K> keySerializer, 
TypeSerializer<N> namespaceSerializer) {
    +                   this.keySerializer = keySerializer;
    +                   this.namespaceSerializer = namespaceSerializer;
    +           }
    +
    +           @Override
    +           public boolean isImmutableType() {
    +                   return false;
    +           }
    +
    +           @Override
    +           public TypeSerializer<InternalTimer<K, N>> duplicate() {
    +                   return this;
    --- End diff --
    
    This means that the result of `duplicate()` is not a "duplication" if 
`keySerializer` or `namespaceSerializer` is stateful.


> Implement efficient deletes for heap based timer service
> --------------------------------------------------------
>
>                 Key: FLINK-9423
>                 URL: https://issues.apache.org/jira/browse/FLINK-9423
>             Project: Flink
>          Issue Type: Improvement
>          Components: Streaming
>    Affects Versions: 1.6.0
>            Reporter: Stefan Richter
>            Assignee: Stefan Richter
>            Priority: Major
>
> The current data structures in the `HeapInternalTimerService` are not able to 
> support efficient timer deletes, the complexity is currently O\(n\), where n 
> is the number of registered timers.
>  
> We can keep track of timer's positions in the priority queue and (in 
> combination with the already existing set/map) have a more efficient 
> algorithm for deletes.



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