flink-libraries/flink-cep/src/test/java/org/apache/flink/cep/nfa/NFAStateAccessTest.java

/*
 * 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.cep.Event;
import org.apache.flink.cep.SubEvent;
import org.apache.flink.cep.nfa.sharedbuffer.SharedBufferAccessor;
import org.apache.flink.cep.pattern.Pattern;
import org.apache.flink.cep.pattern.conditions.IterativeCondition;
import org.apache.flink.cep.pattern.conditions.SimpleCondition;
import org.apache.flink.cep.utils.TestSharedBuffer;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;

import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

import static org.apache.flink.cep.utils.NFAUtils.compile;
import static org.junit.Assert.assertEquals;

/**
 * Tests that check if we do not degrade NFA computation in case of State accesses.
 */
public class NFAStateAccessTest {

	@Test
	public void testComplexBranchingAfterZeroOrMore() throws Exception {
		List<StreamRecord<Event>> inputEvents = new ArrayList<>();

		Event startEvent = new Event(40, "c", 1.0);
		Event middleEvent1 = new Event(41, "a", 2.0);
		Event middleEvent2 = new Event(42, "a", 3.0);
		Event middleEvent3 = new Event(43, "a", 4.0);
		Event end1 = new Event(44, "b", 5.0);
		Event end2 = new Event(45, "d", 6.0);
		Event end3 = new Event(46, "d", 7.0);
		Event end4 = new Event(47, "e", 8.0);

		inputEvents.add(new StreamRecord<>(startEvent, 1));
		inputEvents.add(new StreamRecord<>(middleEvent1, 3));
		inputEvents.add(new StreamRecord<>(middleEvent2, 4));
		inputEvents.add(new StreamRecord<>(middleEvent3, 5));
		inputEvents.add(new StreamRecord<>(end1, 6));
		inputEvents.add(new StreamRecord<>(end2, 7));
		inputEvents.add(new StreamRecord<>(end3, 8));
		inputEvents.add(new StreamRecord<>(end4, 9));

		Pattern<Event, ?> pattern = Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 5726188262756267490L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("c");
			}
		}).followedByAny("middle").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 5726188262756267490L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("a");
			}
		}).oneOrMore().allowCombinations().optional().followedByAny("end1").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 5726188262756267490L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("b");
			}
		}).followedByAny("end2").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 5726188262756267490L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("d");
			}
		}).followedByAny("end3").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 5726188262756267490L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("e");
			}
		});

		NFA<Event> nfa = compile(pattern, false);

		TestSharedBuffer<Event> sharedBuffer = TestSharedBuffer.createTestBuffer(Event.createTypeSerializer());
		for (StreamRecord<Event> inputEvent : inputEvents) {
			try (SharedBufferAccessor<Event> accessor = sharedBuffer.getAccessor()) {
					nfa.process(
					accessor,
					nfa.createInitialNFAState(),
					inputEvent.getValue(),
					inputEvent.getTimestamp());
			}
		}

		assertEquals(2, sharedBuffer.getStateReads());
		assertEquals(3, sharedBuffer.getStateWrites());
		assertEquals(5, sharedBuffer.getStateAccesses());
	}

	@Test
	public void testIterativeWithABACPattern() throws Exception {
		List<StreamRecord<Event>> inputEvents = new ArrayList<>();

		final Event startEvent1 = new Event(40, "start", 1.0);
		final Event startEvent2 = new Event(40, "start", 2.0);
		final Event startEvent3 = new Event(40, "start", 3.0);
		final Event startEvent4 = new Event(40, "start", 4.0);
		final SubEvent middleEvent1 = new SubEvent(41, "foo1", 1.0, 10);
		final SubEvent middleEvent2 = new SubEvent(42, "foo2", 2.0, 10);
		final SubEvent middleEvent3 = new SubEvent(43, "foo3", 3.0, 10);
		final SubEvent middleEvent4 = new SubEvent(43, "foo4", 1.0, 10);
		final Event endEvent = new Event(46, "end", 1.0);

		inputEvents.add(new StreamRecord<>(startEvent1, 1L)); //1
		inputEvents.add(new StreamRecord<Event>(middleEvent1, 2L)); //1

		inputEvents.add(new StreamRecord<>(startEvent2, 2L)); //2
		inputEvents.add(new StreamRecord<>(startEvent3, 2L)); //3
		inputEvents.add(new StreamRecord<Event>(middleEvent2, 2L)); //2

		inputEvents.add(new StreamRecord<>(startEvent4, 2L)); //4
		inputEvents.add(new StreamRecord<Event>(middleEvent3, 2L)); //3
		inputEvents.add(new StreamRecord<Event>(middleEvent4, 2L)); //1
		inputEvents.add(new StreamRecord<>(endEvent, 4L));

		Pattern<Event, ?> pattern = Pattern.<Event>begin("start").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 6215754202506583964L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("start");
			}
		}).followedByAny("middle1").subtype(SubEvent.class).where(new SimpleCondition<SubEvent>() {
			private static final long serialVersionUID = 2178338526904474690L;

			@Override
			public boolean filter(SubEvent value) throws Exception {
				return value.getName().startsWith("foo");
			}
		}).followedBy("middle2").where(new IterativeCondition<Event>() {
			private static final long serialVersionUID = -1223388426808292695L;

			@Override
			public boolean filter(Event value, Context<Event> ctx) throws Exception {
				if (!value.getName().equals("start")) {
					return false;
				}

				double sum = 0.0;
				for (Event e : ctx.getEventsForPattern("middle2")) {
					sum += e.getPrice();
				}
				sum += value.getPrice();
				return Double.compare(sum, 5.0) <= 0;
			}
		}).oneOrMore().followedBy("end").where(new SimpleCondition<Event>() {
			private static final long serialVersionUID = 562590474115118323L;

			@Override
			public boolean filter(Event value) throws Exception {
				return value.getName().equals("end");
			}
		});

		NFA<Event> nfa = compile(pattern, false);

		TestSharedBuffer<Event> sharedBuffer = TestSharedBuffer.createTestBuffer(Event.createTypeSerializer());
		for (StreamRecord<Event> inputEvent : inputEvents) {
			try (SharedBufferAccessor<Event> accessor = sharedBuffer.getAccessor()) {
					nfa.process(
					accessor,
					nfa.createInitialNFAState(),
					inputEvent.getValue(),
					inputEvent.getTimestamp());
			}
		}

		assertEquals(8, sharedBuffer.getStateReads());
		assertEquals(12, sharedBuffer.getStateWrites());
		assertEquals(20, sharedBuffer.getStateAccesses());
	}
}