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https://issues.apache.org/jira/browse/FLINK-7169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119864#comment-16119864
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ASF GitHub Bot commented on FLINK-7169:
---------------------------------------

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

    https://github.com/apache/flink/pull/4331#discussion_r132136797
  
    --- Diff: 
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/AfterMatchSkipStrategy.java
 ---
    @@ -0,0 +1,276 @@
    +/*
    + * 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.cep.nfa;
    +
    +import org.apache.flink.api.common.typeutils.CompatibilityResult;
    +import org.apache.flink.api.common.typeutils.CompatibilityUtil;
    +import 
org.apache.flink.api.common.typeutils.CompositeTypeSerializerConfigSnapshot;
    +import org.apache.flink.api.common.typeutils.TypeDeserializerAdapter;
    +import org.apache.flink.api.common.typeutils.TypeSerializer;
    +import org.apache.flink.api.common.typeutils.TypeSerializerConfigSnapshot;
    +import org.apache.flink.api.common.typeutils.UnloadableDummyTypeSerializer;
    +import org.apache.flink.api.java.tuple.Tuple2;
    +import org.apache.flink.core.memory.DataInputView;
    +import org.apache.flink.core.memory.DataInputViewStreamWrapper;
    +import org.apache.flink.core.memory.DataOutputView;
    +import org.apache.flink.core.memory.DataOutputViewStreamWrapper;
    +
    +import java.io.ByteArrayInputStream;
    +import java.io.ByteArrayOutputStream;
    +import java.io.IOException;
    +import java.io.ObjectInputStream;
    +import java.io.ObjectOutputStream;
    +import java.io.Serializable;
    +import java.util.List;
    +
    +
    +/**
    + * Indicate the skip strategy after a match process.
    + * <p>There're four kinds of strategies:
    + * SKIP_PAST_LAST_EVENT,
    + * SKIP_TO_NEXT_EVENT,
    + * SKIP_TO_FIRST_<code>PATTERN</code> and
    + * SKIP_TO_LAST_<code>PATTERN</code>
    + * </p>
    + */
    +public class AfterMatchSkipStrategy implements Serializable {
    +
    +   // default strategy
    +   SkipStrategy strategy = SkipStrategy.SKIP_TO_NEXT_EVENT;
    +
    +   // fields
    +   String patternName = null;
    +
    +   public AfterMatchSkipStrategy(){
    +           this(SkipStrategy.SKIP_TO_NEXT_EVENT, null);
    +   }
    +
    +   public AfterMatchSkipStrategy(SkipStrategy strategy) {
    +           this(strategy, null);
    +   }
    +
    +   public AfterMatchSkipStrategy(SkipStrategy strategy, String 
patternName) {
    +           if (patternName == null && (strategy == 
SkipStrategy.SKIP_TO_FIRST || strategy == SkipStrategy.SKIP_TO_LAST)) {
    +                   throw new IllegalArgumentException("the patternName 
field can not be empty when SkipStrategy is " + strategy);
    +           }
    +           this.strategy = strategy;
    +           this.patternName = patternName;
    +   }
    +
    +   public SkipStrategy getStrategy() {
    +           return strategy;
    +   }
    +
    +   public String getPatternName() {
    +           return patternName;
    +   }
    +
    +   @Override
    +   public String toString() {
    +           return "AfterMatchStrategy{" +
    +                   "strategy=" + strategy +
    +                   ", patternName=" + patternName +
    +                   '}';
    +   }
    +
    +   /**
    +    * Skip Strategy Enum.
    +    */
    +   public enum SkipStrategy{
    +           SKIP_TO_NEXT_EVENT,
    +           SKIP_PAST_LAST_EVENT,
    +           SKIP_TO_FIRST,
    +           SKIP_TO_LAST
    +   }
    +
    +   /**
    +    * The {@link TypeSerializerConfigSnapshot} serializer configuration to 
be stored with the managed state.
    +    */
    +   public static class AfterMatchSkipStrategyConfigSnapshot extends 
CompositeTypeSerializerConfigSnapshot {
    +
    +           private static final int VERSION = 1;
    +
    +           /**
    +            * This empty constructor is required for deserializing the 
configuration.
    +            */
    +           public AfterMatchSkipStrategyConfigSnapshot() {
    +           }
    +
    +           public AfterMatchSkipStrategyConfigSnapshot(
    +                   TypeSerializer<SkipStrategy> enumSerializer,
    +                   TypeSerializer<String> stringSerializer) {
    +
    +                   super(enumSerializer, stringSerializer);
    +           }
    +
    +           @Override
    +           public int getVersion() {
    +                   return VERSION;
    +           }
    +   }
    +
    +   /**
    +    *  A {@link TypeSerializer} for the {@link AfterMatchSkipStrategy}.
    +    */
    +   public static class AfterMatchSkipStrategySerializer extends 
TypeSerializer<AfterMatchSkipStrategy> {
    +
    +           private final TypeSerializer<SkipStrategy> enumSerializer;
    +           private final TypeSerializer<String> stringSerializer;
    +
    +           public 
AfterMatchSkipStrategySerializer(TypeSerializer<SkipStrategy> enumSerializer, 
TypeSerializer<String> stringSerializer) {
    +                   this.enumSerializer = enumSerializer;
    +                   this.stringSerializer = stringSerializer;
    +           }
    +
    +           @Override
    +           public boolean isImmutableType() {
    +                   return false;
    +           }
    +
    +           @Override
    +           public TypeSerializer<AfterMatchSkipStrategy> duplicate() {
    +                   return new 
AfterMatchSkipStrategySerializer(enumSerializer, stringSerializer);
    +           }
    +
    +           @Override
    +           public AfterMatchSkipStrategy createInstance() {
    +                   return new AfterMatchSkipStrategy();
    +           }
    +
    +           @Override
    +           public AfterMatchSkipStrategy copy(AfterMatchSkipStrategy from) 
{
    +                   try {
    +                           ByteArrayOutputStream baos = new 
ByteArrayOutputStream();
    +                           ObjectOutputStream oos = new 
ObjectOutputStream(baos);
    +
    +                           serialize(from, new 
DataOutputViewStreamWrapper(oos));
    +
    +                           oos.close();
    +                           baos.close();
    +
    +                           byte[] data = baos.toByteArray();
    +
    +                           ByteArrayInputStream bais = new 
ByteArrayInputStream(data);
    +                           ObjectInputStream ois = new 
ObjectInputStream(bais);
    +
    +                           AfterMatchSkipStrategy copy = deserialize(new 
DataInputViewStreamWrapper(ois));
    +                           ois.close();
    +                           bais.close();
    +
    +                           return copy;
    +                   } catch (IOException e) {
    +                           throw new RuntimeException("Could not copy 
AfterMatchSkipStrategy.", e);
    +                   }
    +           }
    +
    +           @Override
    +           public AfterMatchSkipStrategy copy(AfterMatchSkipStrategy from, 
AfterMatchSkipStrategy reuse) {
    +                   return copy(from);
    +           }
    +
    +           @Override
    +           public int getLength() {
    +                   return -1;
    +           }
    +
    +           @Override
    +           public void serialize(AfterMatchSkipStrategy record, 
DataOutputView target) throws IOException {
    +                   enumSerializer.serialize(record.getStrategy(), target);
    +                   stringSerializer.serialize(record.getPatternName(), 
target);
    +           }
    +
    +           @Override
    +           public AfterMatchSkipStrategy deserialize(DataInputView source) 
throws IOException {
    +                   SkipStrategy skipStrategy = 
enumSerializer.deserialize(source);
    +                   String rpv = stringSerializer.deserialize(source);
    +                   return new AfterMatchSkipStrategy(skipStrategy, rpv);
    +           }
    +
    +           @Override
    +           public AfterMatchSkipStrategy 
deserialize(AfterMatchSkipStrategy reuse, DataInputView source) throws 
IOException {
    +                   return deserialize(source);
    +           }
    +
    +           @Override
    +           public void copy(DataInputView source, DataOutputView target) 
throws IOException {
    +                   SkipStrategy skipStrategy = 
enumSerializer.deserialize(source);
    +                   enumSerializer.serialize(skipStrategy, target);
    +                   String rpv = stringSerializer.deserialize(source);
    --- End diff --
    
    `rpv` -> `patternName`


> Support AFTER MATCH SKIP function in CEP library API
> ----------------------------------------------------
>
>                 Key: FLINK-7169
>                 URL: https://issues.apache.org/jira/browse/FLINK-7169
>             Project: Flink
>          Issue Type: Sub-task
>          Components: CEP
>            Reporter: Yueting Chen
>            Assignee: Yueting Chen
>             Fix For: 1.4.0
>
>
> In order to support Oracle's MATCH_RECOGNIZE on top of the CEP library, we 
> need to support AFTER MATCH SKIP function in CEP API.
> There're four options in AFTER MATCH SKIP, listed as follows:
> 1. AFTER MATCH SKIP TO NEXT ROW: resume pattern matching at the row after the 
> first row of the current match.
> 2. AFTER MATCH SKIP PAST LAST ROW: resume pattern matching at the next row 
> after the last row of the current match.
> 3. AFTER MATCH SKIP TO FIST *RPV*: resume pattern matching at the first row 
> that is mapped to the row pattern variable RPV.
> 4. AFTER MATCH SKIP TO LAST *RPV*: resume pattern matching at the last row 
> that is mapped to the row pattern variable RPV.
> I think we can introduce a new function to `CEP` class, which takes a new 
> parameter as AfterMatchSKipStrategy.
> The new API may looks like this
> {code}
> public static <T> PatternStream<T> pattern(DataStream<T> input, Pattern<T, ?> 
> pattern, AfterMatchSkipStrategy afterMatchSkipStrategy) 
> {code}
> We can also make `SKIP TO NEXT ROW` as the default option, because that's 
> what CEP library behaves currently.



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