GridRefreshManager.java

package org.ovirt.engine.ui.userportal.client.components;

import java.util.Date;
import java.util.HashSet;

import org.ovirt.engine.ui.userportal.client.components.GridController;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.event.logical.shared.CloseEvent;
import com.google.gwt.event.logical.shared.CloseHandler;
import com.google.gwt.user.client.Cookies;
import com.google.gwt.user.client.Window;


public class GridRefreshManager {

    // Refresh the grid every 60 seconds by default
    public static final int DEFAULT_REFRESH_RATE = 60;
    
    // Refresh rates (in seconds)
    public static final int[] REFRESH_RATES = new int[]{ 10, 20, 30 ,60 };
    
    // For saving refresh rate on client
    private static final String REFRESH_RATE_COOKIE_NAME = "RefreshRate";
    
    private static GridRefreshManager instance = null;

    private HashSet<GridController<?>> gridControllerList = new HashSet<GridController<?>>();

    private int globalRefreshRate = DEFAULT_REFRESH_RATE;
    
    private GridRefreshManager() {

        // Add window's focus\blur events
        AttachWindowFocusEvents();
        
        // Read refresh rate cookie
        setGlobalRefreshRate(readRefreshRateCookie());
               
        // Save cookie on window close event and window refresh event
        Window.addCloseHandler(new CloseHandler<Window>() {
            @Override
            public void onClose(CloseEvent<Window> event) {
                saveRefreshRateCookie();                
            }
        });
    }
    
    public static GridRefreshManager getInstance() {
        if (instance == null) {
            instance = new GridRefreshManager();
        }
        return instance;
    }

    // Subscribe the specified grid controller to the refresh service
    public void subscribe(GridController<?> controller) {
        if (!gridControllerList.contains(controller)) {
            gridControllerList.add(controller);
            controller.gridChangePerformed();
            
            GWT.log("Subscribe grid: " + controller.getClass().getName() + ", refresh rate: " + controller.getRefreshRate());
        }
    }

    // Unsubscribe the specified grid controller to the refresh service
    public void unsubscribe(GridController<?> controller) {
        if (gridControllerList.contains(controller)) {
            gridControllerList.remove(controller);            
            controller.stopRepeatedSearch();
            
            GWT.log("Unsubscribe grid: " + controller.getClass().getName());
        }
    }
    
    // Return true if the specified controller is subscribed to the service;
    // Otherwise, false
    public boolean isSubscribed(GridController<?> controller) {
        return gridControllerList.contains(controller);
    }  
       
    // Suspend refresh
    public void suspendRefresh() {
        for (GridController<?> controller : gridControllerList) {
            controller.stopRepeatedSearch();
        }
    }
    
    // Refresh grids less frequently while not in focus
    public void backgroundRefresh() {
        for (GridController<?> controller : gridControllerList) {
            if (controller.isRapidTimerRunning()) {
                continue;
            }
            
            controller.stopRepeatedSearch();
            controller.repeatSearch(DEFAULT_REFRESH_RATE * 1000);
            
            GWT.log("Background refresh, grid: " + controller.getClass().getName() + ", refresh rate: " + DEFAULT_REFRESH_RATE);
        }
    }
    
    // Start/Resume refresh
    public void refreshGrids() {
        for (GridController<?> controller : gridControllerList) {
            if (controller.isRapidTimerRunning()) {
                continue;
            }
            
            controller.search();
            controller.repeatSearch(controller.getRefreshRate() * 1000); 
            
            GWT.log("Start/Resume refresh, grid: " + controller.getClass().getName() + ", refresh rate: " + controller.getRefreshRate());
        }
    }
    
    // Set global refresh rate for all grids
    public void setGlobalRefreshRate(int refreshRate) {
        
        this.globalRefreshRate = refreshRate;
        
        for (GridController<?> controller : gridControllerList) {
            controller.setRefreshRate(refreshRate); 
            controller.stopRepeatedSearch();
            refreshGrids();
        }
    }  
    
    // Get global refresh rate
    // (global value - currently, all grids have the refresh same rate)
    public int getGlobalRefreshRate() {
        return globalRefreshRate; 
    }
    
    // Save refresh rate value to a cookie and set expire date to fifty years from now
    // (only a single value is saved - currently, all grids have the refresh same rate)
    private void saveRefreshRateCookie()
    {       
        long expire = new Date().getTime() + (1000 * 60 * 60 * 24 * 365 * 50); // fifty years       
        
        if (gridControllerList.iterator().hasNext()) {
            int refreshRate = gridControllerList.iterator().next().getRefreshRate();
            Cookies.setCookie(REFRESH_RATE_COOKIE_NAME, String.valueOf(refreshRate), new Date(expire)); 
        }           
    }
       
    // Return refresh rate value from the cookie - if exists; Otherwise, return default refresh rate 
    // (connect automatically is true by default). 
    private int readRefreshRateCookie()
    {       
        String refreshRate = Cookies.getCookie(REFRESH_RATE_COOKIE_NAME);
        
        try {    
            return new Integer(refreshRate).intValue();  
        } 
        catch (NumberFormatException e) {    
            return DEFAULT_REFRESH_RATE;  
        }   
    }
        
    private JavaScriptObject activeElement;
    private boolean lastEventWasBlur = false;
   
    public void onWindowFocus() {            
        refreshGrids();
    }
    
    public void onWindowBlur() {     
        backgroundRefresh();        
    }
    
    public native void AttachWindowFocusEvents() /*-{        
        var clientAgentType = @org.ovirt.engine.ui.userportal.client.util.ClientAgentType::new()();
        var browser = clientAgentType.@org.ovirt.engine.ui.userportal.client.util.ClientAgentType::browser;        
        var isIE = browser.toLowerCase() == "explorer";
      
        if (isIE)
        {
            $doc.attachEvent("onfocusin", onFocus);
            $doc.attachEvent("onfocusout", onBlur);
        }
        else
        {
            $wnd.addEventListener("focus", onFocus, false);
            $wnd.addEventListener("blur", onBlur, false);
        }
        
        var context = this;
        function onFocus()
        {
            // only focus if previous event was a blur or we get lots of focus events (On IE)
            if (context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::lastEventWasBlur) {
                context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::lastEventWasBlur = false;
                context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::onWindowFocus()();            
            }
        }        
        function onBlur()
        {
            if (context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::activeElement != $doc.activeElement) {
                context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::activeElement = $doc.activeElement;
            }
            else {
                context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::lastEventWasBlur = true;
                context.@org.ovirt.engine.ui.userportal.client.components.GridRefreshManager::onWindowBlur()();             
            }             
        }
    }-*/;
}