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TheseFoolishThings - Vaadin Enhancements
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/*
 * #%L
 * *********************************************************************************************************************
 * 
 * These Foolish Things - Miscellaneous utilities
 * http://thesefoolishthings.tidalwave.it - git clone [email protected]:tidalwave/thesefoolishthings-src.git
 * %%
 * Copyright (C) 2009 - 2015 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 * 
 * 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.
 * 
 * *********************************************************************************************************************
 * 
 * $Id$
 * 
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.ui.vaadin;

import javax.annotation.Nonnull;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import com.github.wolfie.refresher.Refresher;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;

/***********************************************************************************************************************
 *
 * @author Fabrizio Giudici
 * @author Gabriele Cuccu 
 * @version $Id$
 *
 **********************************************************************************************************************/
@RequiredArgsConstructor @Slf4j
public class RefresherQueue
  {
    @Nonnull
    private final Refresher refresher;
    private boolean started;
    private final Queue pendingJobs = new ConcurrentLinkedQueue();
    private final Refresher.RefreshListener listener = new Refresher.RefreshListener()
      {

        @Override
        public void refresh (final @Nonnull Refresher source)
          {
            log.debug("executing pending jobs...");

            for (;;)
              {
                Runnable job = pendingJobs.poll();

                if (job == null)
                  {
//                    internalStop();
                    break;
                  }

                log.debug(">>>> executing pending job: {} ...", job);
                job.run();
              }
          }
      };

    public void start()
      {
        log.debug("start()");
        refresher.addListener(listener);
      }

    public void stop()
      {
        log.debug("stop()");
        refresher.removeListener(listener);

        synchronized (this)
          {
            if (started)
              {
                internalStop();
              }
          }
      }

    public void invokeLater (final @Nonnull Runnable job)
      {
        log.debug("invokeLater({})", job);
        pendingJobs.add(job);

        synchronized (this)
          {
            if (!started)
              {
                log.debug(">>>> started refresher");
                refresher.setRefreshInterval(500);
                started = true;
              }
          }
      }

    protected synchronized void internalStop()
      {
        refresher.setRefreshInterval(0);
        started = false;
        log.debug(">>>> stopped refresher");
      }
  }