test/java/nio/channels/AsynchronousChannelGroup/Unbounded.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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 4607272 6842687
 * @summary Unit test for AsynchronousChannelGroup
 */

import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.net.*;
import java.util.concurrent.*;
import java.io.IOException;

public class Unbounded {
    // number of concurrent completion handlers
    static final int CONCURRENCY_COUNT = 256;

    public static void main(String[] args) throws Exception {
        // all accepted connections are added to a queue
        final ArrayBlockingQueue<AsynchronousSocketChannel> queue =
            new ArrayBlockingQueue<AsynchronousSocketChannel>(CONCURRENCY_COUNT);

        // create listener to accept connections
        final AsynchronousServerSocketChannel listener =
            AsynchronousServerSocketChannel.open()
                .bind(new InetSocketAddress(0));
        listener.accept((Void)null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
            public void completed(AsynchronousSocketChannel ch, Void att) {
                queue.add(ch);
                listener.accept((Void)null, this);
            }
            public void failed(Throwable exc, Void att) {
            }
        });
        System.out.println("Listener created.");

        // establish lots of connections
        int port = ((InetSocketAddress)(listener.getLocalAddress())).getPort();
        SocketAddress sa = new InetSocketAddress(InetAddress.getLocalHost(), port);
        AsynchronousSocketChannel[] channels =
            new AsynchronousSocketChannel[CONCURRENCY_COUNT];
        for (int i=0; i<CONCURRENCY_COUNT; i++) {
            int attempts = 0;
            for (;;) {
                try {
                    channels[i] = AsynchronousSocketChannel.open();
                    channels[i].connect(sa).get();
                    break;
                } catch (IOException x) {
                    // probably resource issue so back off and retry
                    if (++attempts >= 3)
                        throw x;
                    Thread.sleep(50);
                }
            }
        }
        System.out.println("All connection established.");

        // the barrier where all threads (plus the main thread) wait
        final CyclicBarrier barrier = new CyclicBarrier(CONCURRENCY_COUNT+1);

        // initiate a read operation on each channel.
        for (int i=0; i<CONCURRENCY_COUNT; i++) {
            ByteBuffer buf = ByteBuffer.allocateDirect(100);
            channels[i].read( buf, channels[i],
                new CompletionHandler<Integer,AsynchronousSocketChannel>() {
                    public void completed(Integer bytesRead, AsynchronousSocketChannel ch) {
                        try {
                            ch.close();
                            barrier.await();
                        } catch (Exception x) {
                            throw new AssertionError(x);
                        }
                    }
                    public void failed(Throwable exc, AsynchronousSocketChannel ch) {
                    }
                });
        }
        System.out.println("All read operations outstanding.");

        // write data to each of the accepted connections
        int remaining = CONCURRENCY_COUNT;
        while (remaining > 0) {
            AsynchronousSocketChannel ch = queue.take();
            ch.write(ByteBuffer.wrap("welcome".getBytes())).get();
            ch.close();
            remaining--;
        }

        // wait for all threads to reach the barrier
        System.out.println("Waiting for all threads to reach barrier");
        barrier.await();
        listener.close();
    }
}