jdk-24/test/jdk/java/nio/channels/Selector/SelectAfterRead.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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/* @test
 * @bug 4639943
 * @summary  Checks that Windows behavior matches Solaris for
 *           various read/select combinations.
 * @author kladko
 */

import java.nio.ByteBuffer;
import java.nio.channels.Selector;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;

public class SelectAfterRead {

    private static final int TIMEOUT = 1000;

    public static void main(String[] argv) throws Exception {

        // server: accept connection and write one byte
        try (ByteServer server = new ByteServer();
             SocketChannel sc = SocketChannel.open(server.address())) {

            server.acceptConnection();
            server.write(1);

            try (Selector sel = Selector.open()) {
                sc.read(ByteBuffer.allocate(1));
                sc.configureBlocking(false);
                sc.register(sel, SelectionKey.OP_READ);
                // previously on Windows select would select channel here, although there was
                // nothing to read
                if (sel.selectNow() != 0)
                    throw new Exception("Select returned nonzero value");
            }
        }

        // Now we will test a two reads combination
        // server: accept connection and write two bytes
        try (ByteServer server = new ByteServer();
             SocketChannel sc = SocketChannel.open(server.address())) {

            server.acceptConnection();
            server.write(2);

            try (Selector sel = Selector.open()) {
                sc.configureBlocking(false);
                sc.register(sel, SelectionKey.OP_READ);
                if (sel.select(TIMEOUT) != 1)
                    throw new Exception("One selected key expected");
                sel.selectedKeys().clear();
                // previously on Windows a channel would get selected only once
                if (sel.selectNow() != 1)
                    throw new Exception("One selected key expected");
                // Previously on Windows two consequent reads would cause select()
                // to select a channel, although there was nothing remaining to
                // read in the channel
                if (sc.read(ByteBuffer.allocate(1)) != 1)
                    throw new Exception("One byte expected");
                if (sc.read(ByteBuffer.allocate(1)) != 1)
                    throw new Exception("One byte expected");
                if (sel.selectNow() != 0)
                    throw new Exception("Select returned nonzero value");
            }
        }
    }
}