org.lucidj.vaadinui.SmartPush.java Source code

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Here is the source code for org.lucidj.vaadinui.SmartPush.java

Source

/*
 * Copyright 2017 NEOautus Ltd. (http://neoautus.com)
 *
 * 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 org.lucidj.vaadinui;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.server.VaadinSession;
import com.vaadin.shared.communication.PushMode;
import com.vaadin.ui.UI;

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.locks.Lock;

public class SmartPush {
    private final static Logger log = LoggerFactory.getLogger(BaseVaadinUI.class);

    private final static int CHECK_INTERVAL = 25;
    private final static int PUSH_INTERVAL = 200;
    private Timer push_timer = new Timer();
    private UI ui;
    private volatile long prepare_push;

    public SmartPush(UI ui) {
        if (!ui.getPushConfiguration().getPushMode().isEnabled()) {
            log.info("=============================================");
            log.info("Push is not ENABLED. Will NOT start SmartPush");
            log.info("=============================================");
            return;
        }

        if (ui.getPushConfiguration().getPushMode() != PushMode.MANUAL) {
            log.info("=================================================");
            log.info("Push mode is not MANUAL. Will NOT start SmartPush");
            log.info("=================================================");
            return;
        }

        this.ui = ui;

        push_timer = new Timer();
        push_timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                timer_poll();
            }
        }, CHECK_INTERVAL, CHECK_INTERVAL);
    }

    public void stop() {
        if (push_timer != null) {
            push_timer.cancel();
            push_timer = null;
            ui = null;
        }
    }

    // We just check at fixed interval whether there are pending changes to push.
    // When the push interval is meet with pending changes, we lock the session and push.
    private synchronized void timer_poll() {
        if (!ui.isAttached()) {
            // We never update a detached UI
            return;
        }

        if (ui.isClosing()) {
            // UI.close() issues a final push(), so we can stop right now
            stop();
            return;
        }

        if (!ui.getConnectorTracker().hasDirtyConnectors()) {
            // Nothing to send, reset and keep waiting
            prepare_push = 0;
        } else {
            long now = System.currentTimeMillis();

            // We have data to sync
            if (prepare_push == 0) {
                // Start the timer to prepare push
                prepare_push = now;
            } else if (now - prepare_push > (PUSH_INTERVAL - CHECK_INTERVAL - 1)) {
                VaadinSession session = ui.getSession();
                Lock lock = session.getLockInstance();

                try {
                    lock.lock();
                    ui.push();
                } finally {
                    prepare_push = 0;
                    lock.unlock();
                }
            }
        }
    }
}

// EOF