nifi-commons/nifi-utils/src/test/java/org/apache/nifi/util/timebuffer/TestRingBuffer.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.nifi.util.timebuffer;

import org.apache.nifi.util.RingBuffer;
import org.apache.nifi.util.RingBuffer.ForEachEvaluator;
import org.apache.nifi.util.RingBuffer.IterationDirection;
import org.junit.jupiter.api.Test;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;


/**
 *
 */
public class TestRingBuffer {

    @Test
    public void testGetNewestElement() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        for (int i = 0; i < 11; i++) {
            ringBuffer.add(i);
            assertEquals(i, ringBuffer.getNewestElement().intValue());
        }
    }

    @Test
    public void testAsList() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        final List<Integer> emptyList = ringBuffer.asList();
        assertTrue(emptyList.isEmpty());

        for (int i = 0; i < 3; i++) {
            ringBuffer.add(i);
        }

        List<Integer> list = ringBuffer.asList();
        assertEquals(3, list.size());
        for (int i = 0; i < 3; i++) {
            assertEquals(Integer.valueOf(i), list.get(i));
        }

        for (int i = 3; i < 10; i++) {
            ringBuffer.add(i);
        }

        list = ringBuffer.asList();
        assertEquals(10, list.size());
        for (int i = 0; i < 10; i++) {
            assertEquals(Integer.valueOf(i), list.get(i));
        }
    }

    @Test
    public void testIterateForwards() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        final int[] values = new int[]{3, 5, 20, 7};
        for (final int v : values) {
            ringBuffer.add(v);
        }

        final AtomicInteger countHolder = new AtomicInteger(0);
        ringBuffer.forEach(new ForEachEvaluator<Integer>() {
            int counter = 0;

            @Override
            public boolean evaluate(final Integer value) {
                final int expected = values[counter++];
                countHolder.incrementAndGet();
                assertEquals(expected, value.intValue());
                return true;
            }

        }, IterationDirection.FORWARD);

        assertEquals(4, countHolder.get());
    }

    @Test
    public void testIterateForwardsAfterFull() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        for (int i = 0; i < 12; i++) {
            ringBuffer.add(i);
        }

        final int[] values = new int[]{3, 5, 20, 7};
        for (final int v : values) {
            ringBuffer.add(v);
        }

        ringBuffer.forEach(new ForEachEvaluator<Integer>() {
            int counter = 0;

            @Override
            public boolean evaluate(final Integer value) {
                if (counter < 6) {
                    assertEquals(counter + 6, value.intValue());
                } else {
                    final int expected = values[counter - 6];
                    assertEquals(expected, value.intValue());
                }

                counter++;
                return true;
            }

        }, IterationDirection.FORWARD);
    }

    @Test
    public void testIterateBackwards() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        final int[] values = new int[]{3, 5, 20, 7};
        for (final int v : values) {
            ringBuffer.add(v);
        }

        final AtomicInteger countHolder = new AtomicInteger(0);
        ringBuffer.forEach(new ForEachEvaluator<Integer>() {
            int counter = 0;

            @Override
            public boolean evaluate(final Integer value) {
                final int index = values.length - 1 - counter;
                final int expected = values[index];
                countHolder.incrementAndGet();

                assertEquals(expected, value.intValue());
                counter++;
                return true;
            }

        }, IterationDirection.BACKWARD);

        assertEquals(4, countHolder.get());
    }

    @Test
    public void testIterateBackwardsAfterFull() {
        final RingBuffer<Integer> ringBuffer = new RingBuffer<>(10);

        for (int i = 0; i < 12; i++) {
            ringBuffer.add(i);
        }

        final int[] values = new int[]{3, 5, 20, 7};
        for (final int v : values) {
            ringBuffer.add(v);
        }

        ringBuffer.forEach(new ForEachEvaluator<Integer>() {
            int counter = 0;

            @Override
            public boolean evaluate(final Integer value) {
                if (counter < values.length) {
                    final int index = values.length - 1 - counter;
                    final int expected = values[index];

                    assertEquals(expected, value.intValue());
                    counter++;
                }

                return true;
            }

        }, IterationDirection.BACKWARD);
    }
}