test/jdk/java/nio/MappedByteBuffer/ForceException.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/* @test
 * @bug 6539707
 * @summary Test behavior of force() with respect to throwing exceptions
 * @run main ForceException
 */

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.io.UncheckedIOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

public class ForceException {
    public static void main(String[] args) throws IOException {
        int blockSize = 2048 * 1024;
        int numberOfBlocks = 200;
        int fileLength = numberOfBlocks * blockSize;

        File file = new File(".", "test.dat");
        file.deleteOnExit();
        try (RandomAccessFile raf = new RandomAccessFile(file, "rw")) {
            raf.setLength(fileLength);

            int pos = (numberOfBlocks - 1) * blockSize;
            int size = (int)Math.min(blockSize, fileLength - pos);
            MappedByteBuffer mbb =
                raf.getChannel().map(FileChannel.MapMode.READ_WRITE, pos, size);

            System.out.printf("Write region 0x%s..0x%s%n",
                Long.toHexString(pos), Long.toHexString(size));
            for (int k = 0; k < mbb.limit(); k++) {
                mbb.put(k, (byte)65);
            }

            // Catch and process UncheckedIOException; other Throwables fail
            try {
                System.out.println("Force");
                mbb.force();
            } catch (UncheckedIOException legal) {
                System.out.printf("Caught legal exception %s%n", legal);
                IOException cause = legal.getCause(); // can't be null
                // Throw the cause if flush failed (should be only on Windows)
                if (cause.getMessage().startsWith("Flush failed")) {
                    throw cause;
                }
            }

            System.out.println("OK");
        }
    }
}