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This nifi-utils module should be a general purpose place to store widely and generally useful functions that any component might want to leverage. NO DEPENDENCIES should be added. This module is likely to be leveraged by every extension and should not bring along any other dependencies. The only dependency intended is the nifi-api and even this is expected to be already provided in any case where it would be used. The typical place this util would be found is within a nar and all nars already have nifi-api as a parent dependency. The nifi-api can be thought of as a NiFi Application Container level dependency.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.nifi.remote.io.socket;

import java.io.IOException;
import java.io.OutputStream;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedByInterruptException;
import java.nio.channels.SocketChannel;
import java.util.concurrent.TimeUnit;

public class SocketChannelOutputStream extends OutputStream {

    private static final long CHANNEL_FULL_WAIT_NANOS = TimeUnit.NANOSECONDS.convert(10, TimeUnit.MILLISECONDS);
    private final SocketChannel channel;
    private volatile int timeout = 30000;

    private final ByteBuffer oneByteBuffer = ByteBuffer.allocate(1);

    public SocketChannelOutputStream(final SocketChannel socketChannel) throws IOException {
        // this class expects a non-blocking channel
        socketChannel.configureBlocking(false);
        this.channel = socketChannel;
    }

    public void setTimeout(final int timeoutMillis) {
        this.timeout = timeoutMillis;
    }

    @Override
    public void write(final int b) throws IOException {
        oneByteBuffer.flip();
        oneByteBuffer.clear();
        oneByteBuffer.put((byte) b);
        oneByteBuffer.flip();

        final int timeoutMillis = this.timeout;
        long maxTime = System.currentTimeMillis() + timeoutMillis;
        int bytesWritten;
        while (oneByteBuffer.hasRemaining()) {
            bytesWritten = channel.write(oneByteBuffer);
            if (bytesWritten == 0) {
                if (System.currentTimeMillis() > maxTime) {
                    throw new SocketTimeoutException("Timed out writing to socket");
                }
                try {
                    TimeUnit.NANOSECONDS.sleep(CHANNEL_FULL_WAIT_NANOS);
                } catch (InterruptedException e) {
                    close();
                    Thread.currentThread().interrupt(); // set the interrupt status
                    throw new ClosedByInterruptException(); // simulate an interrupted blocked write operation
                }
            } else {
                return;
            }
        }
    }

    @Override
    public void write(final byte[] b) throws IOException {
        write(b, 0, b.length);
    }

    @Override
    public void write(final byte[] b, final int off, final int len) throws IOException {
        final ByteBuffer buffer = ByteBuffer.wrap(b, off, len);

        final int timeoutMillis = this.timeout;
        long maxTime = System.currentTimeMillis() + timeoutMillis;
        int bytesWritten;
        while (buffer.hasRemaining()) {
            bytesWritten = channel.write(buffer);
            if (bytesWritten == 0) {
                if (System.currentTimeMillis() > maxTime) {
                    throw new SocketTimeoutException("Timed out writing to socket");
                }
                try {
                    TimeUnit.NANOSECONDS.sleep(CHANNEL_FULL_WAIT_NANOS);
                } catch (InterruptedException e) {
                    close();
                    Thread.currentThread().interrupt(); // set the interrupt status
                    throw new ClosedByInterruptException(); // simulate an interrupted blocked write operation
                }
            } else {
                maxTime = System.currentTimeMillis() + timeoutMillis;
            }
        }
    }

    /**
     * Closes the underlying SocketChannel
     *
     * @throws java.io.IOException if issues closing underlying stream
     */
    @Override
    public void close() throws IOException {
        channel.close();
    }
}