net.pterodactylus.sonitus.data.AbstractFilter.java Source code

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Here is the source code for net.pterodactylus.sonitus.data.AbstractFilter.java

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/*
 * Sonitus - AbstractFilter.java - Copyright  2013 David Roden
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.pterodactylus.sonitus.data;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Logger;

import com.google.common.collect.Lists;
import com.google.common.io.Closeables;

/**
 * Abstract {@link Filter} implementation that takes care of managing {@link
 * MetadataListener}s and pipes its input to its output.
 *
 * @author <a href="mailto:bombe@pterodactylus.net">David Bombe Roden</a>
 */
public abstract class AbstractFilter implements Filter {

    /** The logger. */
    private static final Logger logger = Logger.getLogger(AbstractFilter.class.getName());

    /** The name of this filter. */
    private final String name;

    /** The list of metadata listeners. */
    private final List<MetadataListener> metadataListeners = Lists.newCopyOnWriteArrayList();

    /** The current metadata. */
    private final AtomicReference<Metadata> metadata = new AtomicReference<Metadata>();

    /** The input stream from which to read. */
    private InputStream inputStream;

    /** The output stream to which to write. */
    private OutputStream outputStream;

    /**
     * Creates a new abstract filter.
     *
     * @param name
     *       The name of the filter
     */
    protected AbstractFilter(String name) {
        this.name = name;
    }

    //
    // LISTENER MANAGEMENT
    //

    @Override
    public void addMetadataListener(MetadataListener metadataListener) {
        metadataListeners.add(metadataListener);
    }

    @Override
    public void removeMetadataListener(MetadataListener metadataListener) {
        metadataListeners.remove(metadataListener);
    }

    //
    // FILTER METHODS
    //

    @Override
    public String name() {
        return name;
    }

    @Override
    public List<Controller<?>> controllers() {
        return Collections.emptyList();
    }

    @Override
    public Metadata metadata() {
        return metadata.get();
    }

    @Override
    public void metadataUpdated(Metadata metadata) {
        if (metadata.equals(this.metadata.get())) {
            return;
        }
        this.metadata.set(metadata);
        fireMetadataUpdated(metadata);
    }

    @Override
    public void open(Metadata metadata) throws IOException {
        metadataUpdated(metadata);
        inputStream = createInputStream();
        outputStream = createOutputStream();
    }

    @Override
    public void close() {
        try {
            Closeables.close(outputStream, true);
            Closeables.close(inputStream, true);
        } catch (IOException e) {
            /* wont throw. */
        }
    }

    @Override
    public void process(DataPacket dataPacket) throws IOException {
        if (dataPacket.metadata().isPresent()
                && !dataPacket.metadata().get().equalsIgnoreComment(this.metadata.get())) {
            metadataUpdated(dataPacket.metadata().get());
        }
        logger.finest(String.format("Writing %d bytes to %s...", dataPacket.buffer().length, name()));
        outputStream.write(dataPacket.buffer());
        outputStream.flush();
    }

    @Override
    public DataPacket get(int bufferSize) throws IOException {
        byte[] buffer = new byte[bufferSize];
        int read = inputStream.read(buffer);
        if (read == -1) {
            throw new EOFException();
        }
        return new DataPacket(metadata(), Arrays.copyOf(buffer, read));
    }

    //
    // EVENT METHODS
    //

    /**
     * Notifies all registered metadata listeners that the metadata has changed.
     *
     * @param metadata
     *       The new metadata
     */
    protected void fireMetadataUpdated(Metadata metadata) {
        for (MetadataListener metadataListener : metadataListeners) {
            metadataListener.metadataUpdated(this, metadata);
        }
    }

    //
    // SUBCLASS METHODS
    //

    /**
     * Creates the input stream from which {@link net.pterodactylus.sonitus.data.Pipeline}
     * will read the audio data. If you override this, you have to override {@link
     * #createOutputStream()}, too!
     *
     * @return The input stream to read from
     * @throws IOException
     *       if an I/O error occurs
     */
    protected InputStream createInputStream() throws IOException {
        return new PipedInputStream();
    }

    /**
     * Creates the output stream to which {@link net.pterodactylus.sonitus.data.Pipeline}
     * will write the audio data. If you override this, you have to override {@link
     * #createInputStream()}, too!
     *
     * @return The output stream to write to
     * @throws IOException
     *       if an I/O error occurs
     */
    protected OutputStream createOutputStream() throws IOException {
        return new PipedOutputStream((PipedInputStream) inputStream);
    }

}