java-topology/test/jdk/java/nio/MappedByteBuffer/ForceViews.java

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/*
 * @test
 * @bug 4833719
 * @summary Verify MappedByteBuffer force on compact, duplicate, and slice views
 * @run junit ForceViews
 */
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.ReadOnlyBufferException;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.util.function.BiFunction;
import java.util.stream.Stream;

import static java.nio.channels.FileChannel.MapMode.*;
import static java.nio.file.StandardOpenOption.*;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

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

public class ForceViews {

    static record Segment(int position, int length) {}

    public static Stream<Arguments> provider() throws IOException {
        BiFunction<MappedByteBuffer,Segment,MappedByteBuffer> absSlice =
            (m, s) -> { return m.slice(s.position, s.length); };
        BiFunction<MappedByteBuffer,Segment,MappedByteBuffer> relSlice =
            (m, s) -> { m.position(s.position); m.limit(s.position + s.length);
                        return m.slice(); };
        BiFunction<MappedByteBuffer,Segment,MappedByteBuffer> duplicate=
            (m, s) -> { return m.duplicate(); };
        BiFunction<MappedByteBuffer,Segment,MappedByteBuffer> compact =
            (m, s) -> { return m.compact(); };

        return Stream.of
            (Arguments.of("Absolute slice", 256, 512, 128, 128, 32, 32, absSlice),
             Arguments.of("Relative slice", 256, 512, 0, 128, 32, 32, relSlice),
             Arguments.of("Duplicate", 256, 512, 0, 256, 32, 32, duplicate),
             Arguments.of("Compact", 256, 512, 0, 256, 32, 32, compact));
    }

    @ParameterizedTest
    @MethodSource("provider")
    public void test(String tst, int mapPosition, int mapLength,
                     int sliceIndex, int sliceLength, int regionOffset,
                     int regionLength,
                     BiFunction<MappedByteBuffer,Segment,MappedByteBuffer> f)
        throws Exception {

        Path file = Path.of(".", "junk");
        try (FileChannel fc = FileChannel.open(file, CREATE, READ, WRITE, DELETE_ON_CLOSE)) {
            fc.write(ByteBuffer.wrap(new byte[1024]));
            fc.position(0);

            MappedByteBuffer mbb = fc.map(READ_WRITE, mapPosition, mapLength);
            mbb = f.apply(mbb, new Segment(sliceIndex, sliceLength));
            for (int i = regionOffset; i < regionOffset + regionLength; i++) {
                mbb.put(i, (byte)i);
            }
            mbb.force(regionOffset, regionOffset + regionLength);

            int fcPos = mapPosition + sliceIndex + regionOffset;
            int mbbPos = regionOffset;
            int length = regionLength;

            ByteBuffer buf = ByteBuffer.allocate(length);
            fc.position(fcPos);
            fc.read(buf);
            for (int i = 0; i < length; i++) {
                int fcVal = buf.get(i);
                int mbbVal = mbb.get(mbbPos + i);
                int val = regionOffset + i;
                assertEquals(val, fcVal);
                assertEquals(val, mbbVal);
            }
        }
    }
}