ThreadQueue.java

/*
 * Copyright 2014 shannah.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ca.weblite.comiccl.forms;

import com.codename1.io.Log;
import java.io.IOException;
import java.util.ArrayList;




/**
 *
 * @author shannah
 */
public class ThreadQueue  implements Runnable {
    final private ArrayList<Runnable> queue = new ArrayList<Runnable>();
    final Object lock = new Object();
    private Thread self;
    
    public void setSelf(Thread t){
        self = t;
    }
    
    @Override
    public void run(){
        while ( true ){
            synchronized (lock){
                while (queue.isEmpty()){
                    try {
                        lock.wait();
                    } catch (InterruptedException ex) {

                    }
                }
            }
            ArrayList<Runnable> toRun = new ArrayList<Runnable>();
            
            synchronized(lock){
                toRun.addAll(queue);
                queue.clear();
            }
            for ( Runnable r : toRun ){
                try {
                    r.run();
                    
                } catch ( Throwable t){
                    Log.e(t);
                }
            }
            try {
                synchronized(lock){
                    lock.wait(200);
                }
            } catch (InterruptedException ex) {
                Log.e(ex);
            }
        }
        
    }
    
    public void invokeLater(Runnable r){
        synchronized(lock){
            queue.add(r);
            lock.notifyAll();
        }
    }
    
    public void invokeIOAndWait(final IORunnable r) throws IOException {
        if ( Thread.currentThread() == self ){
            //Log.p("Running IO "+r+" on same thread");
            r.run();
            return;
        }
        final IOException[] ex = new IOException[1];
        invokeAndWait(new Runnable(){

            public void run() {
                //Log.p("Running IO "+r+" on dedicated thread");
                try {
                    r.run();
                } catch ( IOException e){
                    ex[0] = e;
                }
            }
            
        });
        if ( ex[0] != null ){
            throw ex[0];
        }
    }
    
    public void invokeAndWait(final Runnable r){
        if ( Thread.currentThread() == self ){
            //Log.p("Running  "+r+" on same thread");
            r.run();
            return;
        }
        final Object o = new Object();
        final boolean[] done = new boolean[1];
        this.invokeLater(new Runnable(){

            public void run() {
                //Log.p("Running IO "+r+" on diff thread");
                try {
                    r.run();
                    
                } finally {
                    synchronized(o){
                        done[0] = true;
                        o.notify();
                    }
                }
                //Log.p("Finished running "+r+" on diff thread");
            }
            
        });
        synchronized(o){
            try {
                //Log.p("Waiting for "+r);
                while ( !done[0] ) o.wait();
                //Log.p("Finished waiting for "+r);
            } catch (InterruptedException ex) {
                //Log.e(ex);
            }
        }
        
    }
    
    public static interface IORunnable {
        public void run() throws IOException;
    }
}

Usage.java

//Start the queue on some thread:
dbThread = new ThreadQueue();
Thread th = Display.getInstance().startThread(dbThread, "DB THREAD");
dbThread.setSelf(th);
th.start();

// Call all SQL code inside dbThread.invokeIOAndWait()
dbThread.invokeIOAndWait(()->{
    daoProvider = new DAOProvider(db, "/setup.sql", DB_VERSION);
    //Log.p("Setting collections dao");
    daoProvider.set("collections", new CollectionDAO(daoProvider));
    //Log.p("Setting issues dao");
    daoProvider.set("issues", new IssueDAO(daoProvider));
    //Log.p("Setting series dao");
    daoProvider.set("series", new SeriesDAO(daoProvider));
});