automenta.knowtention.channel.LineFileChannel.java Source code

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Here is the source code for automenta.knowtention.channel.LineFileChannel.java

Source

/*
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 * and open the template in the editor.
 */
package automenta.knowtention.channel;

import automenta.knowtention.Channel;
import automenta.knowtention.Core;
import automenta.knowtention.Runner;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Watches a file for changes ("tail -f"), creating new nodes for each line with
 * appropriate metadata
 */
public class LineFileChannel extends Runner {

    final String id;
    long delayPeriodMS = 1000;
    private final File file;
    private boolean running = true;
    int numLines = 3;
    Channel channel;

    public LineFileChannel(String id, Channel c, String filename) {
        this.channel = c;
        this.id = id;
        this.file = new File(filename);
    }

    public void stop() {
        running = false;
    }

    @Override
    public void run() {

        FileInputStream fileInputStream = null;
        FileChannel channel = null;
        ByteBuffer buffer = null;
        LinkedList<String> lines = new LinkedList();
        StringBuilder builder = new StringBuilder();
        long lastSize = -1, lastLastModified = -1;

        while (running) {
            try {
                Thread.sleep(delayPeriodMS);
            } catch (InterruptedException ex) {
            }

            lines.clear();
            try {
                fileInputStream = new FileInputStream(file);

                channel = fileInputStream.getChannel();

                long lastModified = file.lastModified();
                long csize = channel.size();
                if ((lastModified == lastLastModified) && (csize == lastSize)) { //also check file update time?
                    fileInputStream.close();
                    continue;
                }

                int currentPos = (int) csize;

                buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, csize);
                buffer.position(currentPos);
                lastSize = csize;
                lastLastModified = lastModified;

                int count = 0;

                for (long i = csize - 1; i >= 0; i--) {

                    char c = (char) buffer.get((int) i);

                    if (c == '\n') {
                        count++;
                        builder.reverse();
                        lines.addFirst(builder.toString());
                        if (count == numLines) {
                            break;
                        }
                        builder.setLength(0);
                    } else
                        builder.append(c);
                }

                update(lines);

                lines.clear();
                buffer.clear();
                channel.close();
                fileInputStream.close();
                fileInputStream = null;

            } catch (Exception ex) {
                Logger.getLogger(LineFileChannel.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        try {
            channel.close();
        } catch (IOException ex) {
            Logger.getLogger(LineFileChannel.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    /*    public void run2() {
        
    BufferedReader input = null;
        
    while (running) {
        
        try {
            Thread.sleep(delayPeriodMS);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            break;
        }
        if (input == null) {
            try {
                input = new BufferedReader(new FileReader(file));
            } catch (FileNotFoundException ex) {
                input = null;
                continue;
            }
        
        }
        String currentLine = null;
        
        try {
            if ((currentLine = input.readLine()) != null) {
                if (currentLine != null) {
                    onNewLine(currentLine);
                }
            }
        } catch (IOException ex) {
        
        }
        
    }
        
    try {
        input.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }
        }*/

    protected void onNewLine(String currentLine) {
        //        long now = System.currentTimeMillis();
        //        String id = "n" + now;
        //        addNode(Core.fromJSON("{ id:'" + id + "', content: '" + currentLine + "' }"));
        //        System.out.println(getSnapshot());
    }

    private synchronized void update(List<String> lines) {

        channel.tx(new Runnable() {
            @Override
            public void run() {

                ArrayNode l = Core.newJson.arrayNode();

                for (int i = 0; i < lines.size(); i++)
                    l.add(lines.get(i));

                ObjectNode o = Core.newJson.objectNode();
                o.put("id", id);
                //o.put("content", (file.getAbsolutePath() + ":" + getClass().getSimpleName()) );
                o.put("list", l);
                channel.addVertex(o);

            }
        });

    }

}