Reduce CPU usage by instead fetching read receipts after related sync…

… events (#168)

src/base.rs

@@ -413,9 +413,6 @@ pub type IambResult<T> = UIResult<T, IambInfo>;
 /// it's reacting to.
 pub type MessageReactions = HashMap<OwnedEventId, (String, OwnedUserId)>;
 
-/// Map of read receipts for different events.
-pub type Receipts = HashMap<OwnedEventId, Vec<OwnedUserId>>;
-
 /// Errors encountered during application use.
 #[derive(thiserror::Error, Debug)]
 pub enum IambError {
@@ -549,7 +546,14 @@ pub struct RoomInfo {
     pub messages: Messages,
 
     /// A map of read markers to display on different events.
-    pub receipts: HashMap<OwnedEventId, Vec<OwnedUserId>>,
+    pub event_receipts: HashMap<OwnedEventId, HashSet<OwnedUserId>>,
+
+    /// A map of the most recent read marker for each user.
+    ///
+    /// Every receipt in this map should also have an entry in [`event_receipts`],
+    /// however not every user has an entry. If a user's most recent receipt is
+    /// older than the oldest loaded event, that user will not be included.
+    pub user_receipts: HashMap<OwnedUserId, OwnedEventId>,
 
     /// An event ID for where we should indicate we've read up to.
     pub read_till: Option<OwnedEventId>,
@@ -698,6 +702,27 @@ impl RoomInfo {
         self.fetch_last.map_or(false, |i| i.elapsed() < ROOM_FETCH_DEBOUNCE)
     }
 
+    fn clear_receipt(&mut self, user_id: &OwnedUserId) -> Option<()> {
+        let old_event_id = self.user_receipts.get(user_id)?;
+        let old_receipts = self.event_receipts.get_mut(old_event_id)?;
+        old_receipts.remove(user_id);
+
+        if old_receipts.is_empty() {
+            self.event_receipts.remove(old_event_id);
+        }
+
+        None
+    }
+
+    pub fn set_receipt(&mut self, user_id: OwnedUserId, event_id: OwnedEventId) {
+        self.clear_receipt(&user_id);
+        self.event_receipts
+            .entry(event_id.clone())
+            .or_default()
+            .insert(user_id.clone());
+        self.user_receipts.insert(user_id, event_id);
+    }
+
     fn get_typers(&self) -> &[OwnedUserId] {
         if let Some((t, users)) = &self.users_typing {
             if t.elapsed() < Duration::from_secs(4) {
@@ -860,26 +885,6 @@ impl ChatStore {
             .unwrap_or_else(|| "Untitled Matrix Room".to_string())
     }
 
-    /// Update the receipts for multiple rooms.
-    pub async fn set_receipts(
-        &mut self,
-        receipts: Vec<(OwnedRoomId, Receipts)>,
-    ) -> Vec<(OwnedRoomId, OwnedEventId)> {
-        let mut updates = vec![];
-
-        for (room_id, receipts) in receipts.into_iter() {
-            if let Some(info) = self.rooms.get_mut(&room_id) {
-                info.receipts = receipts;
-
-                if let Some(read_till) = info.read_till.take() {
-                    updates.push((room_id, read_till));
-                }
-            }
-        }
-
-        return updates;
-    }
-
     /// Mark a room for loading more scrollback.
     pub fn mark_for_load(&mut self, room_id: OwnedRoomId) {
         self.need_load.insert(room_id);

src/message/mod.rs

@@ -2,10 +2,10 @@
 use std::borrow::Cow;
 use std::cmp::{Ord, Ordering, PartialOrd};
 use std::collections::hash_map::DefaultHasher;
+use std::collections::hash_set;
 use std::collections::BTreeMap;
 use std::convert::TryFrom;
 use std::hash::{Hash, Hasher};
-use std::slice::Iter;
 
 use chrono::{DateTime, Local as LocalTz, NaiveDateTime, TimeZone};
 use comrak::{markdown_to_html, ComrakOptions};
@@ -501,7 +501,7 @@ struct MessageFormatter<'a> {
     date: Option<Span<'a>>,
 
     /// Iterator over the users who have read up to this message.
-    read: Iter<'a, OwnedUserId>,
+    read: Option<hash_set::Iter<'a, OwnedUserId>>,
 }
 
 impl<'a> MessageFormatter<'a> {
@@ -533,10 +533,11 @@ impl<'a> MessageFormatter<'a> {
                 // Show read receipts.
                 let user_char =
                     |user: &'a OwnedUserId| -> Span<'a> { settings.get_user_char_span(user) };
+                let mut read = self.read.iter_mut().flatten();
 
-                let a = self.read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
-                let b = self.read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
-                let c = self.read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
+                let a = read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
+                let b = read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
+                let c = read.next().map(user_char).unwrap_or_else(|| Span::raw(" "));
 
                 line.push(Span::raw(" "));
                 line.push(c);
@@ -650,34 +651,31 @@ impl Message {
             let fill = width - USER_GUTTER - TIME_GUTTER - READ_GUTTER;
             let user = self.show_sender(prev, true, info, settings);
             let time = self.timestamp.show_time();
-            let read = match info.receipts.get(self.event.event_id()) {
-                Some(read) => read.iter(),
-                None => [].iter(),
-            };
+            let read = info.event_receipts.get(self.event.event_id()).map(|read| read.iter());
 
             MessageFormatter { settings, cols, orig, fill, user, date, time, read }
         } else if USER_GUTTER + TIME_GUTTER + MIN_MSG_LEN <= width {
             let cols = MessageColumns::Three;
             let fill = width - USER_GUTTER - TIME_GUTTER;
             let user = self.show_sender(prev, true, info, settings);
             let time = self.timestamp.show_time();
-            let read = [].iter();
+            let read = None;
 
             MessageFormatter { settings, cols, orig, fill, user, date, time, read }
         } else if USER_GUTTER + MIN_MSG_LEN <= width {
             let cols = MessageColumns::Two;
             let fill = width - USER_GUTTER;
             let user = self.show_sender(prev, true, info, settings);
             let time = None;
-            let read = [].iter();
+            let read = None;
 
             MessageFormatter { settings, cols, orig, fill, user, date, time, read }
         } else {
             let cols = MessageColumns::One;
             let fill = width.saturating_sub(2);
             let user = self.show_sender(prev, false, info, settings);
             let time = None;
-            let read = [].iter();
+            let read = None;
 
             MessageFormatter { settings, cols, orig, fill, user, date, time, read }
         }

src/tests.rs

@@ -153,7 +153,8 @@ pub fn mock_room() -> RoomInfo {
         keys: mock_keys(),
         messages: mock_messages(),
 
-        receipts: HashMap::new(),
+        event_receipts: HashMap::new(),
+        user_receipts: HashMap::new(),
         read_till: None,
         reactions: HashMap::new(),