CircularBufferTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package jdk.incubator.http.internal.hpack;

import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;
import jdk.incubator.http.internal.hpack.HeaderTable.CircularBuffer;

import java.util.Queue;
import java.util.Random;
import java.util.concurrent.ArrayBlockingQueue;

import static org.testng.Assert.assertEquals;
import static jdk.incubator.http.internal.hpack.TestHelper.newRandom;

public final class CircularBufferTest {

    private final Random r = newRandom();

    @BeforeClass
    public void setUp() {
        r.setSeed(System.currentTimeMillis());
    }

    @Test
    public void queue() {
        for (int capacity = 1; capacity <= 2048; capacity++) {
            queueOnce(capacity, 32);
        }
    }

    @Test
    public void resize() {
        for (int capacity = 1; capacity <= 4096; capacity++) {
            resizeOnce(capacity);
        }
    }

    @Test
    public void downSizeEmptyBuffer() {
        CircularBuffer<Integer> buffer = new CircularBuffer<>(16);
        buffer.resize(15);
    }

    private void resizeOnce(int capacity) {

        int nextNumberToPut = 0;

        Queue<Integer> referenceQueue = new ArrayBlockingQueue<>(capacity);
        CircularBuffer<Integer> buffer = new CircularBuffer<>(capacity);

        // Fill full, so the next add will wrap
        for (int i = 0; i < capacity; i++, nextNumberToPut++) {
            buffer.add(nextNumberToPut);
            referenceQueue.add(nextNumberToPut);
        }
        int gets = r.nextInt(capacity); // [0, capacity)
        for (int i = 0; i < gets; i++) {
            referenceQueue.poll();
            buffer.remove();
        }
        int puts = r.nextInt(gets + 1); // [0, gets]
        for (int i = 0; i < puts; i++, nextNumberToPut++) {
            buffer.add(nextNumberToPut);
            referenceQueue.add(nextNumberToPut);
        }

        Integer[] expected = referenceQueue.toArray(new Integer[0]);
        buffer.resize(expected.length);

        assertEquals(buffer.elements, expected);
    }

    private void queueOnce(int capacity, int numWraps) {

        Queue<Integer> referenceQueue = new ArrayBlockingQueue<>(capacity);
        CircularBuffer<Integer> buffer = new CircularBuffer<>(capacity);

        int nextNumberToPut = 0;
        int totalPuts = 0;
        int putsLimit = capacity * numWraps;
        int remainingCapacity = capacity;
        int size = 0;

        while (totalPuts < putsLimit) {
            assert remainingCapacity + size == capacity;
            int puts = r.nextInt(remainingCapacity + 1); // [0, remainingCapacity]
            remainingCapacity -= puts;
            size += puts;
            for (int i = 0; i < puts; i++, nextNumberToPut++) {
                referenceQueue.add(nextNumberToPut);
                buffer.add(nextNumberToPut);
            }
            totalPuts += puts;
            int gets = r.nextInt(size + 1); // [0, size]
            size -= gets;
            remainingCapacity += gets;
            for (int i = 0; i < gets; i++) {
                Integer expected = referenceQueue.poll();
                Integer actual = buffer.remove();
                assertEquals(actual, expected);
            }
        }
    }
}