From a9e5bc0c953c083df979c382a8e2165155b2211d Mon Sep 17 00:00:00 2001
From: Valter Martinek <martinek@freevision.sk>
Date: Sun, 30 Oct 2022 17:48:27 +0100
Subject: [PATCH] Pre-load meta entries for all chapters for optimization
 (#432)

Load meta entries for all chapters in one query to prevent N+1 queries
---
 .../suwayomi/tachidesk/manga/impl/Chapter.kt       | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Chapter.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Chapter.kt
index a14b937d..b9976cc7 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Chapter.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Chapter.kt
@@ -132,6 +132,9 @@ object Chapter {
                 .associateBy({ it[ChapterTable.url] }, { it })
         }
 
+        val chapterIds = chapterList.map { dbChapterMap.getValue(it.url)[ChapterTable.id] }
+        val chapterMetas = getChaptersMetaMaps(chapterIds)
+
         return chapterList.mapIndexed { index, it ->
 
             val dbChapter = dbChapterMap.getValue(it.url)
@@ -156,7 +159,7 @@ object Chapter {
                 dbChapter[ChapterTable.pageCount],
 
                 chapterList.size,
-                meta = getChapterMetaMap(dbChapter[ChapterTable.id])
+                meta = chapterMetas.getValue(dbChapter[ChapterTable.id])
             )
         }
     }
@@ -193,6 +196,15 @@ object Chapter {
         }
     }
 
+    fun getChaptersMetaMaps(chapterIds: List<EntityID<Int>>): Map<EntityID<Int>, Map<String, String>> {
+        return transaction {
+            ChapterMetaTable.select { ChapterMetaTable.ref inList chapterIds }
+                .groupBy { it[ChapterMetaTable.ref] }
+                .mapValues { it.value.associate { it[ChapterMetaTable.key] to it[ChapterMetaTable.value] } }
+                .withDefault { emptyMap<String, String>() }
+        }
+    }
+
     fun getChapterMetaMap(chapter: EntityID<Int>): Map<String, String> {
         return transaction {
             ChapterMetaTable.select { ChapterMetaTable.ref eq chapter }