threads: check for new notes locally when thread is re-opened

We have a NoteRef cache for threads in memory, which is just a list of
NoteKeys and timestamps.

When reopening a thread, query the local DB to see if there are any new
notes that we might have missed because we weren't actively subscribed
to them.

Signed-off-by: William Casarin <jb55@jb55.com>

src/actionbar.rs

@@ -1,4 +1,9 @@
-use crate::{route::Route, thread::Thread, Damus};
+use crate::{
+    note::NoteRef,
+    route::Route,
+    thread::{Thread, ThreadResult},
+    Damus,
+};
 use enostr::NoteId;
 use nostrdb::Transaction;
 use tracing::{info, warn};
@@ -9,6 +14,79 @@ pub enum BarAction {
     OpenThread,
 }
 
+pub enum BarResult {
+    NewThreadNotes(Vec<NoteRef>),
+}
+
+/// open_thread is called when a note is selected and we need to navigate
+/// to a thread It is responsible for managing the subscription and
+/// making sure the thread is up to date. In a sense, it's a model for
+/// the thread view. We don't have a concept of model/view/controller etc
+/// in egui, but this is the closest thing to that.
+fn open_thread(
+    app: &mut Damus,
+    txn: &Transaction,
+    timeline: usize,
+    selected_note: &[u8; 32],
+) -> Option<BarResult> {
+    {
+        let timeline = &mut app.timelines[timeline];
+        timeline
+            .routes
+            .push(Route::Thread(NoteId::new(selected_note.to_owned())));
+        timeline.navigating = true;
+    }
+
+    let root_id = crate::note::root_note_id_from_selected_id(app, txn, selected_note);
+    let thread_res = app.threads.thread_mut(&app.ndb, txn, root_id);
+
+    // The thread is stale, let's update it
+    let (thread, result) = match thread_res {
+        ThreadResult::Stale(thread) => {
+            let notes = Thread::new_notes(&thread.view.notes, root_id, txn, &app.ndb);
+            //
+            // we can't insert and update the VirtualList now, because we
+            // are already borrowing it mutably. Let's pass it as a
+            // result instead
+            //
+            // thread.view.insert(&notes);
+            (thread, Some(BarResult::NewThreadNotes(notes)))
+        }
+
+        ThreadResult::Fresh(thread) => (thread, None),
+    };
+
+    // only start a subscription on nav and if we don't have
+    // an active subscription for this thread.
+    if thread.subscription().is_none() {
+        *thread.subscription_mut() = app.ndb.subscribe(Thread::filters(root_id)).ok();
+
+        match thread.subscription() {
+            Some(_sub) => {
+                thread.subscribers += 1;
+                info!(
+                    "Locally subscribing to thread. {} total active subscriptions, {} on this thread",
+                    app.ndb.subscription_count(),
+                    thread.subscribers,
+                );
+            }
+            None => warn!(
+                "Error subscribing locally to selected note '{}''s thread",
+                hex::encode(selected_note)
+            ),
+        }
+    } else {
+        thread.subscribers += 1;
+        info!(
+            "Re-using existing thread subscription. {} total active subscriptions, {} on this thread",
+            app.ndb.subscription_count(),
+            thread.subscribers,
+        )
+    }
+
+    result
+}
+
 impl BarAction {
     pub fn execute(
         self,
@@ -16,7 +94,7 @@ impl BarAction {
         timeline: usize,
         replying_to: &[u8; 32],
         txn: &Transaction,
-    ) {
+    ) -> Option<BarResult> {
         match self {
             BarAction::Reply => {
                 let timeline = &mut app.timelines[timeline];
@@ -24,48 +102,10 @@ impl BarAction {
                     .routes
                     .push(Route::Reply(NoteId::new(replying_to.to_owned())));
                 timeline.navigating = true;
+                None
             }
 
-            BarAction::OpenThread => {
-                {
-                    let timeline = &mut app.timelines[timeline];
-                    timeline
-                        .routes
-                        .push(Route::Thread(NoteId::new(replying_to.to_owned())));
-                    timeline.navigating = true;
-                }
-
-                let root_id = crate::note::root_note_id_from_selected_id(app, txn, replying_to);
-                let thread = app.threads.thread_mut(&app.ndb, txn, root_id);
-
-                // only start a subscription on nav and if we don't have
-                // an active subscription for this thread.
-                if thread.subscription().is_none() {
-                    *thread.subscription_mut() = app.ndb.subscribe(Thread::filters(root_id)).ok();
-
-                    match thread.subscription() {
-                        Some(_sub) => {
-                            thread.subscribers += 1;
-                            info!(
-                                "Locally subscribing to thread. {} total active subscriptions, {} on this thread",
-                                app.ndb.subscription_count(),
-                                thread.subscribers,
-                            );
-                        }
-                        None => warn!(
-                            "Error subscribing locally to selected note '{}''s thread",
-                            hex::encode(replying_to)
-                        ),
-                    }
-                } else {
-                    thread.subscribers += 1;
-                    info!(
-                        "Re-using existing thread subscription. {} total active subscriptions, {} on this thread",
-                        app.ndb.subscription_count(),
-                        thread.subscribers,
-                    )
-                }
-            }
+            BarAction::OpenThread => open_thread(app, txn, timeline, replying_to),
         }
     }
 }

src/app.rs

@@ -887,9 +887,14 @@ fn thread_unsubscribe(app: &mut Damus, id: &[u8; 32]) {
 
         debug!("thread unsubbing from root_id {}", hex::encode(root_id));
 
-        app.threads
-            .thread_mut(&app.ndb, &txn, root_id)
-            .decrement_sub()
+        let thread = app.threads.thread_mut(&app.ndb, &txn, root_id).get_ptr();
+        let unsub = thread.decrement_sub();
+
+        if let Ok(DecrementResult::LastSubscriber(_subid)) = unsub {
+            *thread.subscription_mut() = None;
+        }
+
+        unsub
     };
 
     match unsubscribe {

src/thread.rs

@@ -2,6 +2,7 @@ use crate::note::NoteRef;
 use crate::timeline::{TimelineTab, ViewFilter};
 use crate::Error;
 use nostrdb::{Filter, Ndb, Subscription, Transaction};
+use std::cmp::Ordering;
 use std::collections::HashMap;
 use tracing::debug;
 
@@ -51,15 +52,13 @@ impl Thread {
         let filters = Thread::filters_since(root_id, last_note.created_at - 60);
 
         if let Ok(results) = ndb.query(txn, filters, 1000) {
+            debug!("got {} results from thread update", results.len());
             results
                 .into_iter()
                 .map(NoteRef::from_query_result)
                 .collect()
         } else {
-            debug!(
-                "got no results from thread update for {}",
-                hex::encode(root_id)
-            );
+            debug!("got no results from thread update",);
             vec![]
         }
     }
@@ -67,17 +66,17 @@ impl Thread {
     pub fn decrement_sub(&mut self) -> Result<DecrementResult, Error> {
         debug!("decrementing sub {:?}", self.subscription().map(|s| s.id));
         self.subscribers -= 1;
-        if self.subscribers == 0 {
-            // unsub from thread
-            if let Some(sub) = self.subscription() {
-                Ok(DecrementResult::LastSubscriber(sub.id))
-            } else {
-                Err(Error::no_active_sub())
+
+        match self.subscribers.cmp(&0) {
+            Ordering::Equal => {
+                if let Some(sub) = self.subscription() {
+                    Ok(DecrementResult::LastSubscriber(sub.id))
+                } else {
+                    Err(Error::no_active_sub())
+                }
             }
-        } else if self.subscribers < 0 {
-            Err(Error::unexpected_sub_count(self.subscribers))
-        } else {
-            Ok(DecrementResult::ActiveSubscribers)
+            Ordering::Less => Err(Error::unexpected_sub_count(self.subscribers)),
+            Ordering::Greater => Ok(DecrementResult::ActiveSubscribers),
         }
     }
 
@@ -121,6 +120,27 @@ pub struct Threads {
     pub root_id_to_thread: HashMap<[u8; 32], Thread>,
 }
 
+pub enum ThreadResult<'a> {
+    Fresh(&'a mut Thread),
+    Stale(&'a mut Thread),
+}
+
+impl<'a> ThreadResult<'a> {
+    pub fn get_ptr(self) -> &'a mut Thread {
+        match self {
+            Self::Fresh(ptr) => ptr,
+            Self::Stale(ptr) => ptr,
+        }
+    }
+
+    pub fn is_stale(&self) -> bool {
+        match self {
+            Self::Fresh(_ptr) => false,
+            Self::Stale(_ptr) => true,
+        }
+    }
+}
+
 impl Threads {
     pub fn thread_expected_mut(&mut self, root_id: &[u8; 32]) -> &mut Thread {
         self.root_id_to_thread
@@ -129,17 +149,17 @@ impl Threads {
     }
 
     pub fn thread_mut<'a>(
-        &mut self,
+        &'a mut self,
         ndb: &Ndb,
         txn: &Transaction,
         root_id: &[u8; 32],
-    ) -> &mut Thread {
+    ) -> ThreadResult<'a> {
         // we can't use the naive hashmap entry API here because lookups
         // require a copy, wait until we have a raw entry api. We could
         // also use hashbrown?
 
         if self.root_id_to_thread.contains_key(root_id) {
-            return self.root_id_to_thread.get_mut(root_id).unwrap();
+            return ThreadResult::Stale(self.root_id_to_thread.get_mut(root_id).unwrap());
         }
 
         // looks like we don't have this thread yet, populate it
@@ -150,7 +170,7 @@ impl Threads {
             debug!("couldnt find root note root_id:{}", hex::encode(root_id));
             self.root_id_to_thread
                 .insert(root_id.to_owned(), Thread::new(vec![]));
-            return self.root_id_to_thread.get_mut(root_id).unwrap();
+            return ThreadResult::Fresh(self.root_id_to_thread.get_mut(root_id).unwrap());
         };
 
         // we don't have the thread, query for it!
@@ -172,7 +192,7 @@ impl Threads {
         debug!("found thread with {} notes", notes.len());
         self.root_id_to_thread
             .insert(root_id.to_owned(), Thread::new(notes));
-        self.root_id_to_thread.get_mut(root_id).unwrap()
+        ThreadResult::Fresh(self.root_id_to_thread.get_mut(root_id).unwrap())
     }
 
     //fn thread_by_id(&self, ndb: &Ndb, id: &[u8; 32]) -> &mut Thread {

src/timeline.rs

@@ -40,7 +40,7 @@ impl<'a> TimelineSource<'a> {
                 let thread = if app.threads.root_id_to_thread.contains_key(root_id) {
                     app.threads.thread_expected_mut(root_id)
                 } else {
-                    app.threads.thread_mut(&app.ndb, txn, root_id)
+                    app.threads.thread_mut(&app.ndb, txn, root_id).get_ptr()
                 };
 
                 &mut thread.view
@@ -57,7 +57,7 @@ impl<'a> TimelineSource<'a> {
                 let thread = if app.threads.root_id_to_thread.contains_key(root_id) {
                     app.threads.thread_expected_mut(root_id)
                 } else {
-                    app.threads.thread_mut(&app.ndb, txn, root_id)
+                    app.threads.thread_mut(&app.ndb, txn, root_id).get_ptr()
                 };
 
                 thread.subscription()
@@ -213,6 +213,9 @@ impl TimelineTab {
     }
 
     pub fn insert(&mut self, new_refs: &[NoteRef]) {
+        if new_refs.is_empty() {
+            return;
+        }
         let num_prev_items = self.notes.len();
         let (notes, merge_kind) = crate::timeline::merge_sorted_vecs(&self.notes, new_refs);
 

src/ui/thread.rs

@@ -79,7 +79,11 @@ impl<'a> ThreadView<'a> {
                 }
 
                 let (len, list) = {
-                    let thread = self.app.threads.thread_mut(&self.app.ndb, &txn, root_id);
+                    let thread = self
+                        .app
+                        .threads
+                        .thread_mut(&self.app.ndb, &txn, root_id)
+                        .get_ptr();
 
                     let len = thread.view.notes.len();
                     (len, &mut thread.view.list)
@@ -92,7 +96,11 @@ impl<'a> ThreadView<'a> {
                         ui.spacing_mut().item_spacing.x = 4.0;
 
                         let note_key = {
-                            let thread = self.app.threads.thread_mut(&self.app.ndb, &txn, root_id);
+                            let thread = self
+                                .app
+                                .threads
+                                .thread_mut(&self.app.ndb, &txn, root_id)
+                                .get_ptr();
                             thread.view.notes[start_index].key
                         };
 

src/ui/timeline.rs

@@ -1,4 +1,4 @@
-use crate::{draft::DraftSource, ui, ui::note::PostAction, Damus};
+use crate::{actionbar::BarResult, draft::DraftSource, ui, ui::note::PostAction, Damus};
 use egui::containers::scroll_area::ScrollBarVisibility;
 use egui::{Direction, Layout};
 use egui_tabs::TabColor;
@@ -56,6 +56,7 @@ fn timeline_ui(ui: &mut egui::Ui, app: &mut Damus, timeline: usize, reversed: bo
         .show(ui, |ui| {
             let view = app.timelines[timeline].current_view();
             let len = view.notes.len();
+            let mut bar_result: Option<BarResult> = None;
             view.list
                 .clone()
                 .borrow_mut()
@@ -92,7 +93,10 @@ fn timeline_ui(ui: &mut egui::Ui, app: &mut Damus, timeline: usize, reversed: bo
                             .show(ui);
 
                         if let Some(action) = resp.action {
-                            action.execute(app, timeline, note.id(), &txn);
+                            let br = action.execute(app, timeline, note.id(), &txn);
+                            if br.is_some() {
+                                bar_result = br;
+                            }
                         } else if resp.response.clicked() {
                             debug!("clicked note");
                         }
@@ -103,6 +107,16 @@ fn timeline_ui(ui: &mut egui::Ui, app: &mut Damus, timeline: usize, reversed: bo
 
                     1
                 });
+
+            if let Some(br) = bar_result {
+                match br {
+                    // update the thread for next render if we have new notes
+                    BarResult::NewThreadNotes(notes) => {
+                        let view = app.timelines[timeline].current_view_mut();
+                        view.insert(&notes);
+                    }
+                }
+            }
         });
 }