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8272297: FileInputStream should override transferTo() for better perf…
…ormance

Reviewed-by: alanb
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Brian Burkhalter committed Aug 16, 2021
1 parent 3677734 commit 82688258f676e6be8a603f6ab744d52728e3478b
Showing 2 changed files with 148 additions and 0 deletions.
@@ -354,6 +354,24 @@ public byte[] readNBytes(int len) throws IOException {
return (capacity == nread) ? buf : Arrays.copyOf(buf, nread);
}

/**
* {@inheritDoc}
*/
public long transferTo(OutputStream out) throws IOException {
long transferred = 0L;
if (out instanceof FileOutputStream fos) {
FileChannel fc = getChannel();
long pos = fc.position();
transferred = fc.transferTo(pos, Long.MAX_VALUE, fos.getChannel());
long newPos = pos + transferred;
fc.position(newPos);
if (newPos >= fc.size()) {
return transferred;
}
}
return transferred + super.transferTo(out);
}

private long length() throws IOException {
return length0();
}
@@ -0,0 +1,130 @@
/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/

/*
* @test
* @library /test/lib
* @build jdk.test.lib.RandomFactory
* @run main TransferTo
* @bug 8272297
* @summary Test FileInputStream.transferTo(FileOutputStream)
* @key randomness
*/
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Random;
import jdk.test.lib.RandomFactory;

public class TransferTo {
private static int MIN_SIZE = 10_000;
private static int MAX_SIZE_INCR = 100_000_000 - MIN_SIZE;

private static int ITERATIONS = 10;

private static final Random RND = RandomFactory.getRandom();

public static void main(String[] args) throws IOException {
File dir = new File(".");
File in = File.createTempFile("src", ".dat", dir);
in.deleteOnExit();

int length = MIN_SIZE + RND.nextInt(MAX_SIZE_INCR);
byte[] bytes = new byte[length];

try (RandomAccessFile rafi = new RandomAccessFile(in, "rw")) {
rafi.write(bytes);
}

File out = File.createTempFile("dst", ".dat", dir);
out.deleteOnExit();

for (int i = 0; i < ITERATIONS; i++) {
int posIn = RND.nextInt(length);
int posOut = RND.nextInt(MIN_SIZE);

try (RandomAccessFile rafo = new RandomAccessFile(out, "rw")) {
rafo.setLength(posOut);
}

test(in, posIn, out, posOut);

out.delete();
out = File.createTempFile("dst", ".dat", dir);
out.deleteOnExit();
}
}

private static void test(File in, int posIn, File out, int posOut)
throws IOException {
try (FileInputStream fis = new FileInputStream(in)) {
try (FileChannel fci = fis.getChannel()) {
fci.position(posIn);
long size = fci.size();
long length = size - posIn;
int count = Math.toIntExact(length);

try (FileOutputStream fos = new FileOutputStream(out)) {
try (FileChannel fco = fos.getChannel()) {
fco.position(posOut);

long transferred = fis.transferTo(fos);
if (transferred != count)
fail(posIn, size, posOut,
"Transferred " + transferred +
", expected " + count);

if (fci.position() != posIn + count)
fail(posIn, size, posOut,
"Input position " + fci.position() +
", expected " + posIn + count);

if (fco.position() != posOut + count)
fail(posIn, size, posOut,
"Output position " + fco.position() +
", expected " + posOut + count);

byte[] bytesIn = Files.readAllBytes(in.toPath());
byte[] bytesOut = Files.readAllBytes(out.toPath());
if (!Arrays.equals(bytesIn, posIn, posIn + count,
bytesOut, posOut, posOut + count))
fail(posIn, size, posOut, "Contents unequal");
}
}
}
}
}

private static void fail(int posIn, long size, int posOut,
String msg) {
System.out.printf("Failure for posIn %s, size %d, posOut %d%n",
posIn, size, posOut);
throw new RuntimeException(msg);
}
}

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