EBusSerialConnector.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.ebus.internal.connection;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.TooManyListenersException;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import gnu.io.CommPortIdentifier;
import gnu.io.NoSuchPortException;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;
import gnu.io.UnsupportedCommOperationException;

/**
 * This is the serial implementation of the eBus connector. It only handles
 * serial specific connection/disconnection. All logic is handled by
 * abstract class AbstractEBusConnector.
 *
 * @author Christian Sowada
 * @since 1.7.0
 */
public class EBusSerialConnector extends AbstractEBusWriteConnector implements SerialPortEventListener {

    private static final Logger logger = LoggerFactory.getLogger(EBusSerialConnector.class);

    /** The serial object */
    private SerialPort serialPort;

    /** The serial port name */
    private String port;

    /** output stream for eBus communication */
    private OutputStream outputStream;

    /** input stream for eBus communication */
    private InputStream inputStream;

    /**
     * @param port
     */
    public EBusSerialConnector(String port) {
        this.port = port;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.openhab.binding.ebus.connection.AbstractEBusConnector#connect()
     */
    @Override
    protected boolean connect() throws IOException {
        try {

            final CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(port);

            if (portIdentifier != null) {

                serialPort = portIdentifier.open("org.openhab.binding.ebus", 2000);
                serialPort.setSerialPortParams(2400, SerialPort.DATABITS_8, SerialPort.STOPBITS_1,
                        SerialPort.PARITY_NONE);

                // set timeout 10 sec.
                serialPort.disableReceiveThreshold();
                serialPort.enableReceiveTimeout(10000);

                // use event to let readByte wait until data is available, optimize cpu usage
                serialPort.addEventListener(this);
                serialPort.notifyOnDataAvailable(true);

                outputStream = serialPort.getOutputStream();
                inputStream = serialPort.getInputStream();

                return super.connect();
            }

        } catch (NoSuchPortException e) {
            logger.error("Unable to connect to serial port {}", port);

        } catch (PortInUseException e) {
            logger.error("Serial port {} is already in use", port);

        } catch (UnsupportedCommOperationException e) {
            logger.error(e.toString(), e);

        } catch (TooManyListenersException e) {
            logger.error("Too many listeners error!", e);
        }

        serialPort = null;
        return false;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.openhab.binding.ebus.connection.AbstractEBusConnector#disconnect()
     */
    @Override
    protected boolean disconnect() throws IOException {

        if (serialPort == null) {
            return true;
        }

        // run the serial.close in a new not-interrupted thread to
        // prevent an IllegalMonitorStateException error
        Thread shutdownThread = new Thread(new Runnable() {
            @Override
            public void run() {

                IOUtils.closeQuietly(inputStream);
                IOUtils.closeQuietly(outputStream);

                if (serialPort != null) {
                    serialPort.close();
                    serialPort = null;
                }
            }
        }, "eBUS serial shutdown thread");

        shutdownThread.start();

        try {
            // wait for shutdown
            shutdownThread.join(2000);
        } catch (InterruptedException e) {
        }

        return true;
    }

    /*
     * (non-Javadoc)
     * 
     * @see gnu.io.SerialPortEventListener#serialEvent(gnu.io.SerialPortEvent)
     */
    @Override
    public void serialEvent(SerialPortEvent event) {
        if (event.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
            synchronized (inputStream) {
                inputStream.notifyAll();
            }
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.openhab.binding.ebus.internal.connection.AbstractEBusConnector#readByte()
     */
    @Override
    protected int readByte(boolean lowLatency) throws IOException {

        if (lowLatency) {
            return inputStream.read();
        } else {
            if (inputStream.available() > 0) {
                return inputStream.read();

            } else {
                synchronized (inputStream) {
                    try {
                        inputStream.wait(3000);
                        return inputStream.read();
                    } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                    }
                    return -1;
                }
            }
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.openhab.binding.ebus.internal.connection.AbstractEBusWriteConnector#writeByte(int)
     */
    @Override
    protected void writeByte(int b) throws IOException {
        outputStream.write(b);
        // no flush, sometimes it blocks infinitely
    }

    @Override
    protected boolean isReceiveBufferEmpty() throws IOException {
        return inputStream.available() == 0;
    }

    @Override
    protected boolean isConnected() {
        return inputStream != null;
    }

    @Override
    protected void resetInputBuffer() throws IOException {
        inputStream.skip(inputStream.available());
    }

    @Override
    protected InputStream getInputStream() {
        return inputStream;
    }
}