From 83cd5e57a203826ca6c22e2f92fda218287d5fe9 Mon Sep 17 00:00:00 2001
From: Zlatin Balevsky <zlatinb@gmail.com>
Date: Mon, 23 Mar 2020 08:47:05 +0000
Subject: [PATCH] only refresh feeds table if something changes.  This prevents
 the hover menu from flickering

---
 .../java/com/muwire/webui/FeedManager.java    |  8 ++++++++
 .../java/com/muwire/webui/FeedServlet.java    |  4 +++-
 webui/src/main/js/feeds.js                    | 19 +++++++++++++++++--
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/webui/src/main/java/com/muwire/webui/FeedManager.java b/webui/src/main/java/com/muwire/webui/FeedManager.java
index ed90a7c2..0b3ff24d 100644
--- a/webui/src/main/java/com/muwire/webui/FeedManager.java
+++ b/webui/src/main/java/com/muwire/webui/FeedManager.java
@@ -24,6 +24,7 @@ public class FeedManager {
     private final Core core;
     private final FileManager fileManager;
     private final Map<Persona, RemoteFeed> remoteFeeds = new ConcurrentHashMap<>();
+    private volatile long revision;
     
     public FeedManager(Core core, FileManager fileManager) {
         this.core = core;
@@ -34,14 +35,20 @@ public class FeedManager {
         return remoteFeeds;
     }
     
+    long getRevision() {
+        return revision;
+    }
+    
     public void onFeedLoadedEvent(FeedLoadedEvent e) {
        remoteFeeds.put(e.getFeed().getPublisher(), new RemoteFeed(e.getFeed()));
+       revision++;
     }
     
     public void onUIFeedConfigurationEvent(UIFeedConfigurationEvent e) {
         if (!e.isNewFeed()) 
             return;
         remoteFeeds.put(e.getFeed().getPublisher(), new RemoteFeed(e.getFeed()));
+        revision++;
     }
     
     public void onFeedFetchEvent(FeedFetchEvent e) {
@@ -50,6 +57,7 @@ public class FeedManager {
             return; // hmm
         feed.getFeed().setStatus(e.getStatus());
         feed.revision++;
+        revision++;
     }
     
     public void onFeedItemFetchedEvent(FeedItemFetchedEvent e) {
diff --git a/webui/src/main/java/com/muwire/webui/FeedServlet.java b/webui/src/main/java/com/muwire/webui/FeedServlet.java
index 63d81a04..4cf0b7da 100644
--- a/webui/src/main/java/com/muwire/webui/FeedServlet.java
+++ b/webui/src/main/java/com/muwire/webui/FeedServlet.java
@@ -43,7 +43,9 @@ public class FeedServlet extends HttpServlet {
         StringBuilder sb = new StringBuilder();
         sb.append("<?xml version='1.0' encoding='UTF-8'?>");
         
-        if (section.equals("feeds")) {
+        if (section.equals("revision")) {
+            sb.append("<Revision>").append(feedManager.getRevision()).append("</Revision>");
+        } else if (section.equals("feeds")) {
             List<WrappedFeed> feeds = feedManager.getRemoteFeeds().values().stream().
                     map(rf -> new WrappedFeed(rf, core.getFeedManager().getFeedItems(rf.getFeed().getPublisher()).size())).
                     collect(Collectors.toList());
diff --git a/webui/src/main/js/feeds.js b/webui/src/main/js/feeds.js
index c3790852..6a126ff0 100644
--- a/webui/src/main/js/feeds.js
+++ b/webui/src/main/js/feeds.js
@@ -116,10 +116,24 @@ class Item {
 
 
 function initFeeds() {
-	setTimeout(refreshFeeds, 1)
-	setInterval(refreshFeeds, 3000)
+	setTimeout(fetchRevision, 1)
+	setInterval(fetchRevision, 3000)
 }
 
+function fetchRevision() {
+	var xmlhttp = new XMLHttpRequest()
+	xmlhttp.onreadystatechange = function() {
+		if (this.readyState == 4 && this.status == 200) {
+			var newRevision = parseInt(this.responseXML.getElementsByTagName("Revision")[0].childNodes[0].nodeValue)
+			if (newRevision > revision) {
+				revision = newRevision
+				refreshFeeds()
+			}
+		}
+	}
+	xmlhttp.open("GET", "/MuWire/Feed?section=revision", true)
+	xmlhttp.send()
+}
 
 function refreshFeeds() {
 	var xmlhttp = new XMLHttpRequest()
@@ -375,6 +389,7 @@ function download(infoHash) {
 	xmlhttp.send("action=download&host=" + hostB64 + "&infoHash=" + infoHash)
 }
 
+var revision = 0
 var feeds = new Map()
 var currentFeed = null