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From GitBox <...@apache.org>
Subject [GitHub] dawidwys closed pull request #6758: [FLINK-10417][cep] Added option to throw exception on pattern variable mis…
Date Mon, 01 Oct 2018 07:46:39 GMT
dawidwys closed pull request #6758: [FLINK-10417][cep] Added option to throw exception on pattern
variable mis…
URL: https://github.com/apache/flink/pull/6758
 
 
   

This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:

As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):

diff --git a/docs/dev/libs/cep.md b/docs/dev/libs/cep.md
index ad321bf71b5..d7f915fc62e 100644
--- a/docs/dev/libs/cep.md
+++ b/docs/dev/libs/cep.md
@@ -1385,6 +1385,23 @@ Pattern.begin("patternName", skipStrategy)
 </div>
 </div>
 
+{% warn Attention %} For SKIP_TO_FIRST/LAST there are two options how to handle cases when
there are no elements mapped to
+the specified variable. By default a NO_SKIP strategy will be used in this case. The other
option is to throw exception in such situation.
+One can enable this option by:
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+AfterMatchSkipStrategy.skipToFirst(patternName).throwExceptionOnMiss()
+{% endhighlight %}
+</div>
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+AfterMatchSkipStrategy.skipToFirst(patternName).throwExceptionOnMiss()
+{% endhighlight %}
+</div>
+</div>
+
 ## Detecting Patterns
 
 After specifying the pattern sequence you are looking for, it is time to apply it to your
input stream to detect
diff --git a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/AfterMatchSkipStrategy.java
b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/AfterMatchSkipStrategy.java
index 8151a124af4..f4448a35560 100644
--- a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/AfterMatchSkipStrategy.java
+++ b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/AfterMatchSkipStrategy.java
@@ -43,8 +43,8 @@
 	 * @param patternName the pattern name to skip to
 	 * @return the created AfterMatchSkipStrategy
 	 */
-	public static AfterMatchSkipStrategy skipToFirst(String patternName) {
-		return new SkipToFirstStrategy(patternName);
+	public static SkipToFirstStrategy skipToFirst(String patternName) {
+		return new SkipToFirstStrategy(patternName, false);
 	}
 
 	/**
@@ -53,8 +53,8 @@ public static AfterMatchSkipStrategy skipToFirst(String patternName) {
 	 * @param patternName the pattern name to skip to
 	 * @return the created AfterMatchSkipStrategy
 	 */
-	public static AfterMatchSkipStrategy skipToLast(String patternName) {
-		return new SkipToLastStrategy(patternName);
+	public static SkipToLastStrategy skipToLast(String patternName) {
+		return new SkipToLastStrategy(patternName, false);
 	}
 
 	/**
@@ -62,7 +62,7 @@ public static AfterMatchSkipStrategy skipToLast(String patternName) {
 	 *
 	 * @return the created AfterMatchSkipStrategy
 	 */
-	public static AfterMatchSkipStrategy skipPastLastEvent() {
+	public static SkipPastLastStrategy skipPastLastEvent() {
 		return SkipPastLastStrategy.INSTANCE;
 	}
 
@@ -71,7 +71,7 @@ public static AfterMatchSkipStrategy skipPastLastEvent() {
 	 *
 	 * @return the created AfterMatchSkipStrategy
 	 */
-	public static AfterMatchSkipStrategy noSkip() {
+	public static NoSkipStrategy noSkip() {
 		return NoSkipStrategy.INSTANCE;
 	}
 
diff --git a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToElementStrategy.java
b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToElementStrategy.java
new file mode 100644
index 00000000000..5554151ccbd
--- /dev/null
+++ b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToElementStrategy.java
@@ -0,0 +1,89 @@
+/*
+ * 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.aftermatch;
+
+import org.apache.flink.cep.nfa.sharedbuffer.EventId;
+import org.apache.flink.util.FlinkRuntimeException;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+abstract class SkipToElementStrategy extends AfterMatchSkipStrategy {
+	private static final long serialVersionUID = 7127107527654629026L;
+	private final String patternName;
+	private final boolean shouldThrowException;
+
+	SkipToElementStrategy(String patternName, boolean shouldThrowException) {
+		this.patternName = checkNotNull(patternName);
+		this.shouldThrowException = shouldThrowException;
+	}
+
+	@Override
+	public boolean isSkipStrategy() {
+		return true;
+	}
+
+	@Override
+	protected boolean shouldPrune(EventId startEventID, EventId pruningId) {
+		return startEventID != null && startEventID.compareTo(pruningId) < 0;
+	}
+
+	@Override
+	protected EventId getPruningId(Collection<Map<String, List<EventId>>>
match) {
+		EventId pruningId = null;
+		for (Map<String, List<EventId>> resultMap : match) {
+			List<EventId> pruningPattern = resultMap.get(patternName);
+			if (pruningPattern == null || pruningPattern.isEmpty()) {
+				if (shouldThrowException) {
+					throw new FlinkRuntimeException(String.format(
+						"Could not skip to %s. No such element in the found match %s",
+						patternName,
+						resultMap));
+				}
+			} else {
+				pruningId = max(pruningId, pruningPattern.get(getIndex(pruningPattern.size())));
+			}
+		}
+
+		return pruningId;
+	}
+
+	@Override
+	public Optional<String> getPatternName() {
+		return Optional.of(patternName);
+	}
+
+	/**
+	 * Tells which element from the list of events mapped to *PatternName* to use.
+	 *
+	 * @param size number of elements mapped to the *PatternName*
+	 * @return index of event mapped to *PatternName* to use for pruning
+	 */
+	abstract int getIndex(int size);
+
+	/**
+	 * Enables throwing exception if no events mapped to the *PatternName*. If not enabled and
no events were mapped,
+	 * {@link NoSkipStrategy} will be used
+	 */
+	public abstract SkipToElementStrategy throwExceptionOnMiss();
+}
diff --git a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToFirstStrategy.java
b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToFirstStrategy.java
index 7d7be4a4b1e..e8befebe5fc 100644
--- a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToFirstStrategy.java
+++ b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToFirstStrategy.java
@@ -18,59 +18,30 @@
 
 package org.apache.flink.cep.nfa.aftermatch;
 
-import org.apache.flink.cep.nfa.sharedbuffer.EventId;
-
-import java.util.Collection;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-
-import static org.apache.flink.util.Preconditions.checkNotNull;
-
 /**
  * Discards every partial match that contains event of the match preceding the first of *PatternName*.
  */
-public class SkipToFirstStrategy extends AfterMatchSkipStrategy {
-
+public final class SkipToFirstStrategy extends SkipToElementStrategy {
 	private static final long serialVersionUID = 7127107527654629026L;
-	private final String patternName;
 
-	SkipToFirstStrategy(String patternName) {
-		this.patternName = checkNotNull(patternName);
+	SkipToFirstStrategy(String patternName, boolean shouldThrowException) {
+		super(patternName, shouldThrowException);
 	}
 
 	@Override
-	public boolean isSkipStrategy() {
-		return true;
-	}
-
-	@Override
-	protected boolean shouldPrune(EventId startEventID, EventId pruningId) {
-		return startEventID != null && startEventID.compareTo(pruningId) < 0;
-	}
-
-	@Override
-	protected EventId getPruningId(Collection<Map<String, List<EventId>>>
match) {
-		EventId pruniningId = null;
-		for (Map<String, List<EventId>> resultMap : match) {
-			List<EventId> pruningPattern = resultMap.get(patternName);
-			if (pruningPattern != null && !pruningPattern.isEmpty()) {
-				pruniningId = max(pruniningId, pruningPattern.get(0));
-			}
-		}
-
-		return pruniningId;
+	public SkipToElementStrategy throwExceptionOnMiss() {
+		return new SkipToFirstStrategy(getPatternName().get(), true);
 	}
 
 	@Override
-	public Optional<String> getPatternName() {
-		return Optional.of(patternName);
+	int getIndex(int size) {
+		return 0;
 	}
 
 	@Override
 	public String toString() {
 		return "SkipToFirstStrategy{" +
-			"patternName='" + patternName + '\'' +
+			"patternName='" + getPatternName().get() + '\'' +
 			'}';
 	}
 }
diff --git a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToLastStrategy.java
b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToLastStrategy.java
index 0f6c3eddcfb..3c33bd13f62 100644
--- a/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToLastStrategy.java
+++ b/flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/aftermatch/SkipToLastStrategy.java
@@ -18,59 +18,30 @@
 
 package org.apache.flink.cep.nfa.aftermatch;
 
-import org.apache.flink.cep.nfa.sharedbuffer.EventId;
-
-import java.util.Collection;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-
-import static org.apache.flink.util.Preconditions.checkNotNull;
-
 /**
  * Discards every partial match that contains event of the match preceding the last of *PatternName*.
  */
-public class SkipToLastStrategy extends AfterMatchSkipStrategy {
+public final class SkipToLastStrategy extends SkipToElementStrategy {
 	private static final long serialVersionUID = 7585116990619594531L;
-	private final String patternName;
 
-	SkipToLastStrategy(String patternName) {
-		this.patternName = checkNotNull(patternName);
-	}
-
-	@Override
-	public boolean isSkipStrategy() {
-		return true;
+	SkipToLastStrategy(String patternName, boolean shouldThrowException) {
+		super(patternName, shouldThrowException);
 	}
 
 	@Override
-	protected boolean shouldPrune(EventId startEventID, EventId pruningId) {
-		return startEventID != null && startEventID.compareTo(pruningId) < 0;
-	}
-
-	@Override
-	protected EventId getPruningId(Collection<Map<String, List<EventId>>>
match) {
-		EventId pruningId = null;
-		for (Map<String, List<EventId>> resultMap : match) {
-			List<EventId> pruningPattern = resultMap.get(patternName);
-
-			if (pruningPattern != null && !pruningPattern.isEmpty()) {
-				pruningId = max(pruningId, pruningPattern.get(pruningPattern.size() - 1));
-			}
-		}
-
-		return pruningId;
+	public SkipToElementStrategy throwExceptionOnMiss() {
+		return new SkipToLastStrategy(getPatternName().get(), true);
 	}
 
 	@Override
-	public Optional<String> getPatternName() {
-		return Optional.of(patternName);
+	int getIndex(int size) {
+		return size - 1;
 	}
 
 	@Override
 	public String toString() {
 		return "SkipToLastStrategy{" +
-			"patternName='" + patternName + '\'' +
+			"patternName='" + getPatternName().get() + '\'' +
 			'}';
 	}
 }
diff --git a/flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/AfterMatchSkipITCase.java
b/flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/AfterMatchSkipITCase.java
index 4462d103164..6681090d8b2 100644
--- a/flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/AfterMatchSkipITCase.java
+++ b/flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/AfterMatchSkipITCase.java
@@ -24,6 +24,7 @@
 import org.apache.flink.cep.pattern.conditions.IterativeCondition;
 import org.apache.flink.cep.pattern.conditions.SimpleCondition;
 import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
+import org.apache.flink.util.FlinkRuntimeException;
 import org.apache.flink.util.TestLogger;
 
 import org.apache.flink.shaded.guava18.com.google.common.collect.Lists;
@@ -432,6 +433,74 @@ public boolean filter(Event value) throws Exception {
 		));
 	}
 
+	@Test(expected = FlinkRuntimeException.class)
+	public void testSkipToFirstNonExistentPosition() throws Exception {
+		MissedSkipTo.compute(AfterMatchSkipStrategy.skipToFirst("b").throwExceptionOnMiss());
+
+		//exception should be thrown
+	}
+
+	@Test
+	public void testSkipToFirstNonExistentPositionWithoutException() throws Exception {
+		List<List<Event>> resultingPatterns = MissedSkipTo.compute(AfterMatchSkipStrategy.skipToFirst("b"));
+
+		compareMaps(resultingPatterns, Collections.singletonList(
+			Lists.newArrayList(MissedSkipTo.a, MissedSkipTo.c)
+		));
+	}
+
+	@Test(expected = FlinkRuntimeException.class)
+	public void testSkipToLastNonExistentPosition() throws Exception {
+		MissedSkipTo.compute(AfterMatchSkipStrategy.skipToLast("b").throwExceptionOnMiss());
+
+		//exception should be thrown
+	}
+
+	@Test
+	public void testSkipToLastNonExistentPositionWithoutException() throws Exception {
+		List<List<Event>> resultingPatterns = MissedSkipTo.compute(AfterMatchSkipStrategy.skipToFirst("b"));
+
+		compareMaps(resultingPatterns, Collections.singletonList(
+			Lists.newArrayList(MissedSkipTo.a, MissedSkipTo.c)
+		));
+	}
+
+	static class MissedSkipTo {
+		static Event a = new Event(1, "a", 0.0);
+		static Event c = new Event(4, "c", 0.0);
+
+		static List<List<Event>> compute(AfterMatchSkipStrategy skipStrategy) throws
Exception {
+			List<StreamRecord<Event>> streamEvents = new ArrayList<>();
+
+			streamEvents.add(new StreamRecord<>(a));
+			streamEvents.add(new StreamRecord<>(c));
+
+			Pattern<Event, ?> pattern = Pattern.<Event>begin("a").where(
+				new SimpleCondition<Event>() {
+
+					@Override
+					public boolean filter(Event value) throws Exception {
+						return value.getName().contains("a");
+					}
+				}
+			).next("b").where(new SimpleCondition<Event>() {
+				@Override
+				public boolean filter(Event value) throws Exception {
+					return value.getName().contains("b");
+				}
+			}).oneOrMore().optional().consecutive()
+				.next("c").where(new SimpleCondition<Event>() {
+					@Override
+					public boolean filter(Event value) throws Exception {
+						return value.getName().contains("c");
+					}
+				});
+			NFA<Event> nfa = compile(pattern, false);
+
+			return feedNFA(streamEvents, nfa, skipStrategy);
+		}
+	}
+
 	@Test
 	public void testSkipToLastWithOneOrMore() throws Exception {
 		List<StreamRecord<Event>> streamEvents = new ArrayList<>();


 

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