source: other-projects/FileTransfer-WebSocketPair/testGXTWithGreenstone/src/com/gs3/testGXT/server/ProgressBarHandshakeServiceImpl.java@ 33053

package com.gs3.testGXT.server;

import java.util.LinkedList;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.gs3.testGXT.client.services.ProgressBarHandshakeService;
import com.gs3.testGXT.server.Greenstone.GWTFileQueue;

@SuppressWarnings("serial")
public class ProgressBarHandshakeServiceImpl extends RemoteServiceServlet implements ProgressBarHandshakeService {
    
    private static String DONE = "Completed";
    private static String STOP = "Cancelled";
    private static String WAITING = "Non-Completed";
    private static String PROGRESS_TOKEN = "Token";
    
    private final int CHUNK_SIZE = 150;
    private final int SLIDING_WINDOW = 450;
    
    //the synchronized object to be used for keeping track of job progress/long polling
    private Object monitor = GWTFileQueue.monitor;
    
    @Override
    public LinkedList<String[]> shakeHands() {
        // TODO Auto-generated method stub
        synchronized (monitor) {
            /** check that either the queue itself has contents, 
             *  or that there is a currently active job in progress.
             *  The two part check is needed because items get culled 
             *  from the queue before the job actually starts, 
             *  rather than when the job is completed.
             */
            if(GWTFileQueue.files_in_queue != 0 || GWTFileQueue.isQueueBusy()) { //file hasn't finished copying             
                //System.err.println("Files in queue!);
                GWTFileQueue.setAllowance(CHUNK_SIZE);
                monitor.notify();
                try {
                    monitor.wait(); //I think I have some sync issues: this should hopefully fix it
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else {
                monitor.notify();
            }
            
            int full_count = GWTFileQueue.job_size;
            int done_count = GWTFileQueue.done_size;
            
            //ternary needed to account for the case where we get f(0)/f(0) => NaN - ie, empty files
            double progress = full_count == 0 ? 0 : (float)done_count/(float)full_count;
            
            LinkedList<String[]> str = new LinkedList<String[]>();
            
            if(GWTFileQueue.files_in_queue == 0 && !GWTFileQueue.isQueueBusy()) {               
                System.err.println("Zero files in queue!");             
                GWTFileQueue.job_size = GWTFileQueue.done_size = 0;
                /*if(GWTFileQueue.wasCancelled()) {
                    System.err.println("Cancelled!");
                    str.add(new String[] {STOP, "" + 0});
                }
                else {*/
                //TODO: fix
                str.add(new String[] {DONE, "1.0"});
                System.err.println("Done with files (Completed)");
                //}
                return str;
            }
            else {
                str.add(new String[] {WAITING, "" + progress});
            }
            
            //str -> [action] [source] (target)
            //ie:     copying  myfile to mylocation
            //ie:     deleting myfile from myfolder
            //ie:     moving myfolder to myotherfolder
            String token;
            if((token = GWTFileQueue.currentJob) != null) {
                token = "{0}%: " + token;
            }
            else
                token = "Transfer in progress - {0}% Complete";
            
            str.add(new String[] {PROGRESS_TOKEN, token});
            
            System.err.println("Progress: " + progress);        
            
            if(GWTFileQueue.files_in_queue != 0) {
                GWTFileQueue.setAllowance(SLIDING_WINDOW);  
            }
            
            return str;
        }
    }
}