From 4cd8c80226f65789202dda6aa65da57c81ffde50 Mon Sep 17 00:00:00 2001
From: Akinwale Ariwodola <akinwale@gmail.com>
Date: Mon, 13 Jan 2020 12:05:02 +0100
Subject: [PATCH] optimise download manager update broadcasts

---
 app                                           |  2 +-
 .../java/io/lbry/browser/DownloadManager.java | 30 +++++++++++++++++--
 .../java/io/lbry/browser/LbrynetService.java  | 21 ++++++++++---
 3 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/app b/app
index 24d580ea..55f61a85 160000
--- a/app
+++ b/app
@@ -1 +1 @@
-Subproject commit 24d580ea13a36f1e7515af8208cef924f049796c
+Subproject commit 55f61a85f01f2d1b786c4cd0f4e8cc46a986717b
diff --git a/src/main/java/io/lbry/browser/DownloadManager.java b/src/main/java/io/lbry/browser/DownloadManager.java
index ffb7f4bf..b0673d53 100644
--- a/src/main/java/io/lbry/browser/DownloadManager.java
+++ b/src/main/java/io/lbry/browser/DownloadManager.java
@@ -18,10 +18,11 @@ import com.facebook.react.bridge.ReactMethod;
 import io.lbry.browser.receivers.NotificationDeletedReceiver;
 
 import java.text.DecimalFormat;
-import java.util.HashMap;
-import java.util.Random;
-import java.util.List;
 import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.List;
+import java.util.Random;
 
 public class DownloadManager {
     private Context context;
@@ -30,6 +31,9 @@ public class DownloadManager {
 
     private List<String> completedDownloads = new ArrayList<String>();
 
+    // maintain a map of uris to writtenBytes, so that we check if it's changed and don't flood RN with update events every 500ms
+    private Map<String, Double> writtenDownloadBytes = new HashMap<String, Double>();
+
     private HashMap<Integer, NotificationCompat.Builder> builders = new HashMap<Integer, NotificationCompat.Builder>();
 
     private HashMap<String, Integer> downloadIdNotificationIdMap = new HashMap<String, Integer>();
@@ -120,6 +124,26 @@ public class DownloadManager {
         return intent;
     }
 
+    public void updateWrittenBytesForDownload(String id, double writtenBytes) {
+        if (!writtenDownloadBytes.containsKey(id)) {
+            writtenDownloadBytes.put(id, writtenBytes);
+        }
+    }
+
+    public double getWrittenBytesForDownload(String id) {
+        if (writtenDownloadBytes.containsKey(id)) {
+            return writtenDownloadBytes.get(id);
+        }
+
+        return -1;
+    }
+
+    public void clearWrittenBytesForDownload(String id) {
+        if (writtenDownloadBytes.containsKey(id)) {
+            writtenDownloadBytes.remove(id);
+        }
+    }
+
     public void startDownload(String id, String filename) {
         if (filename == null || filename.trim().length() == 0) {
             return;
diff --git a/src/main/java/io/lbry/browser/LbrynetService.java b/src/main/java/io/lbry/browser/LbrynetService.java
index 6fc7e2be..e3126629 100644
--- a/src/main/java/io/lbry/browser/LbrynetService.java
+++ b/src/main/java/io/lbry/browser/LbrynetService.java
@@ -257,6 +257,7 @@ public class LbrynetService extends PythonService {
                                     String uri = String.format("lbry://%s#%s", claimName, claimId);
 
                                     if (!downloadManager.isDownloadActive(uri) && !downloadManager.isDownloadCompleted(uri)) {
+                                        downloadManager.clearWrittenBytesForDownload(uri);
                                         File file = new File(downloadPath);
                                         Intent intent = createDownloadEventIntent(uri, outpoint, item.toString());
                                         intent.putExtra("action", "start");
@@ -320,18 +321,29 @@ public class LbrynetService extends PythonService {
 
                             File file = new File(downloadPath);
                             Intent intent = createDownloadEventIntent(uri, outpoint, item.toString());
+                            boolean shouldSendBroadcast = true;
                             if (downloadManager.isDownloadActive(uri)) {
                                 if (writtenBytes >= totalBytes || completed) {
                                     // completed download
+                                    downloadManager.clearWrittenBytesForDownload(uri);
                                     intent.putExtra("action", "complete");
                                     downloadManager.completeDownload(uri, file.getName(), totalBytes);
                                 } else {
-                                    intent.putExtra("action", "update");
-                                    intent.putExtra("progress", (writtenBytes / totalBytes) * 100);
-                                    downloadManager.updateDownload(uri, file.getName(), writtenBytes, totalBytes);
+                                    double prevWrittenBytes = downloadManager.getWrittenBytesForDownload(uri);
+                                    if (prevWrittenBytes == writtenBytes) {
+                                        // no change, don't send an update event
+                                        shouldSendBroadcast = false;
+                                    }
+                                    downloadManager.updateWrittenBytesForDownload(uri, writtenBytes);
+
+                                    if (shouldSendBroadcast) {
+                                        intent.putExtra("action", "update");
+                                        intent.putExtra("progress", (writtenBytes / totalBytes) * 100);
+                                        downloadManager.updateDownload(uri, file.getName(), writtenBytes, totalBytes);
+                                    }
                                 }
 
-                                if (context != null) {
+                                if (context != null && shouldSendBroadcast) {
                                     context.sendBroadcast(intent);
                                 }
                             } else {
@@ -340,6 +352,7 @@ public class LbrynetService extends PythonService {
                                     continue;
                                 }
                                 if (!completed && downloadPath != null) {
+                                    downloadManager.clearWrittenBytesForDownload(uri);
                                     intent.putExtra("action", "start");
                                     downloadManager.startDownload(uri, file.getName());
                                     if (context != null) {