FileConnection.java

package edu.colostate.vchill.file;

import edu.colostate.vchill.ControlMessage;
import edu.colostate.vchill.TypedControlMessage;
import edu.colostate.vchill.cache.CacheMain;
import edu.colostate.vchill.connection.Connection;

import java.io.File;
import java.util.Collection;
import java.util.LinkedHashSet;

/**
 * Adapter class to make disk files act like a network connection.
 * This implementation is not synchronized; it must be synchronized externally.
 *
 * @author Jochen Deyke
 * @author jpont
 * @version 2009-05-14
 */
public final class FileConnection extends Connection {
    private Collection<String> dirList;

    /**
     * @param cache the cache shared by the entire backend
     */
    public FileConnection(final CacheMain cache) {
        super(cache);
        this.dirList = new LinkedHashSet<String>();
        Thread prefetch = new Thread(new CacheThread(this), "FileCacheThread");
        prefetch.setDaemon(true);
        prefetch.setPriority(Thread.NORM_PRIORITY);
        prefetch.start();
    }

    @Override
    public boolean disconnect() {
        return false; //always keep in list
    }

    @Override
    public void reconnect() {
    }

    @Override
    public boolean isConnected() {
        return false;   //used so the menu doesn't enable the disconnect option
    }

    public void addFile(final File file) {
        String name = FileFunctions.getDecoratedName(file);
        if (name != null) this.dirList.add(name);
    }

    @Override
    public Collection<String> getDirectory(final ControlMessage key) {
        String dir = key.getDir();
        if (dir.length() < 1) return this.connected ? this.dirList : this.cache.getDirectory(key);
        return this.connected ? FileFunctions.getDirectory(dir) : this.cache.getDirectory(key);
    }

    @Override
    public Collection<String> getSweepList(final ControlMessage key) {
        return this.connected ? FileFunctions.getSweepList(key.getDir(), key.getFile()) : this.cache.getSweepList(key);
    }

    protected class CacheThread implements Runnable {
        private FileConnection fileConn;

        CacheThread(FileConnection fileConn) {
            this.fileConn = fileConn;
        }

        public void run() {
            TypedControlMessage command;
            while (true) {
                do { //get new command
                    command = commands.peek();
                    if (command == null || //cache.getCompleteFlag(command.message, command.types) ||
                            command.message.getDir() == null || command.message.getFile() == null ||
                            command.message.getSweep() == null) {
                        commands.remove(command);
                        Thread.yield();
                    } else {
                        break;
                    }
                } while (true);
                try { //add rays to cache
                    FileFunctions.load(fileConn, command.message, cache);
                } catch (Exception e) {
                    fileConn.setIsSweepDone(true);
                    System.out.println("Exception in FileConnection.CacheThread: " + e);
                    e.printStackTrace();
                }
                commands.remove(command); //done with request
            }
        }
    }
}