first iteration of faster sorting

CHANGELOG.md

@@ -13,6 +13,7 @@
 - start ephemeral timer when seen status is synchronized via IMAP #3122
 - do not delete duplicate messages on IMAP immediately to accidentally deleting
   the last copy #3138
+- speed up loading of chat messages #3171
 
 ### Changes
 - add more SMTP logging #3093

src/chat.rs

@@ -2241,26 +2241,34 @@ pub async fn get_chat_msgs(
                 };
 
             Ok((
-                row.get::<_, MsgId>("id")?,
                 row.get::<_, i64>("timestamp")?,
+                row.get::<_, MsgId>("id")?,
                 !is_info_msg,
             ))
         }
     } else {
         |row: &rusqlite::Row| {
             Ok((
-                row.get::<_, MsgId>("id")?,
                 row.get::<_, i64>("timestamp")?,
+                row.get::<_, MsgId>("id")?,
                 false,
             ))
         }
     };
     let process_rows = |rows: rusqlite::MappedRows<_>| {
+        // It is faster to sort here rather than
+        // let sqlite execute an ORDER BY clause.
+        let mut sorted_rows = Vec::new();
+        for row in rows {
+            let (ts, curr_id, exclude_message): (i64, MsgId, bool) = row?;
+            sorted_rows.push((ts, curr_id, exclude_message));
+        }
+        sorted_rows.sort_unstable();
+
         let mut ret = Vec::new();
         let mut last_day = 0;
         let cnv_to_local = dc_gm2local_offset();
-        for row in rows {
+        for (ts, curr_id, exclude_message) in sorted_rows {
-            let (curr_id, ts, exclude_message): (MsgId, i64, bool) = row?;
             if let Some(marker_id) = marker1before {
                 if curr_id == marker_id {
                     ret.push(ChatItem::Marker1);
@@ -2296,8 +2304,7 @@ pub async fn get_chat_msgs(
                     m.param GLOB \"*S=*\"
                     OR m.from_id == ?
                     OR m.to_id == ?
-                )
+                );",
-              ORDER BY m.timestamp, m.id;",
                 paramsv![chat_id, DC_CONTACT_ID_INFO, DC_CONTACT_ID_INFO],
                 process_row,
                 process_rows,
@@ -2307,11 +2314,10 @@ pub async fn get_chat_msgs(
         context
             .sql
             .query_map(
-                "SELECT m.id AS id, m.timestamp AS timestamp
+                "SELECT m.id as id, m.timestamp as timestamp
                FROM msgs m
               WHERE m.chat_id=?
-                AND m.hidden=0
+                AND m.hidden=0;",
-              ORDER BY m.timestamp, m.id;",
                 paramsv![chat_id],
                 process_row,
                 process_rows,