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https://issues.apache.org/jira/browse/FLINK-7169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119865#comment-16119865
]
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_r132176196
--- 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> {
--- End diff --
If we remove `AfterMatchSkipStrategy` from `NFA` I think a custom
`TypeSerializer` will be unnecessary.
> 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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