From cd100aae15538415dbc896d59732e4b9710c89d1 Mon Sep 17 00:00:00 2001
From: ByteHamster <info@bytehamster.com>
Date: Sat, 24 Oct 2020 11:38:31 +0200
Subject: Improve performance and memory usage of 'recent pubdate' feed sort
 option

---
 .../de/danoeh/antennapod/core/storage/DBReader.java | 21 ++++-----------------
 .../antennapod/core/storage/PodDBAdapter.java       | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+), 17 deletions(-)

(limited to 'core')

diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java b/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
index c8368506b..5b226ef92 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
@@ -850,24 +850,11 @@ public final class DBReader {
                 }
             };
         } else {
+            final Map<Long, Long> recentPubDates = adapter.getMostRecentItemDates();
             comparator = (lhs, rhs) -> {
-                if (lhs.getItems() == null || lhs.getItems().size() == 0) {
-                    List<FeedItem> items = DBReader.getFeedItemList(lhs);
-                    lhs.setItems(items);
-                }
-                if (rhs.getItems() == null || rhs.getItems().size() == 0) {
-                    List<FeedItem> items = DBReader.getFeedItemList(rhs);
-                    rhs.setItems(items);
-                }
-                if (lhs.getMostRecentItem() == null) {
-                    return 1;
-                } else if (rhs.getMostRecentItem() == null) {
-                    return -1;
-                } else {
-                    Date d1 = lhs.getMostRecentItem().getPubDate();
-                    Date d2 = rhs.getMostRecentItem().getPubDate();
-                    return d2.compareTo(d1);
-                }
+                long dateLhs = recentPubDates.containsKey(lhs.getId()) ? recentPubDates.get(lhs.getId()) : 0;
+                long dateRhs = recentPubDates.containsKey(rhs.getId()) ? recentPubDates.get(rhs.getId()) : 0;
+                return Long.compare(dateRhs, dateLhs);
             };
         }
 
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/PodDBAdapter.java b/core/src/main/java/de/danoeh/antennapod/core/storage/PodDBAdapter.java
index e552cc180..775485880 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/storage/PodDBAdapter.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/PodDBAdapter.java
@@ -21,8 +21,10 @@ import org.apache.commons.io.FileUtils;
 import java.io.File;
 import java.io.IOException;
 import java.util.Date;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Set;
 
 import de.danoeh.antennapod.core.feed.Chapter;
@@ -1189,6 +1191,25 @@ public class PodDBAdapter {
         return conditionalFeedCounterRead(whereRead, feedIds);
     }
 
+    public final Map<Long, Long> getMostRecentItemDates() {
+        final String query = "SELECT " + KEY_FEED + ","
+                + " MAX(" + TABLE_NAME_FEED_ITEMS + "." + KEY_PUBDATE + ") AS most_recent_pubdate"
+                + " FROM " + TABLE_NAME_FEED_ITEMS
+                + " GROUP BY " + KEY_FEED;
+
+        Cursor c = db.rawQuery(query, null);
+        Map<Long, Long> result = new HashMap<>();
+        if (c.moveToFirst()) {
+            do {
+                long feedId = c.getLong(0);
+                long date = c.getLong(1);
+                result.put(feedId, date);
+            } while (c.moveToNext());
+        }
+        c.close();
+        return result;
+    }
+
     public final int getNumberOfDownloadedEpisodes() {
         final String query = "SELECT COUNT(DISTINCT " + KEY_ID + ") AS count FROM " + TABLE_NAME_FEED_MEDIA +
                 " WHERE " + KEY_DOWNLOADED + " > 0";
-- 
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