implement leech handling

Also change the default for new users to "tag only"

pylib/anki/scheduler.py

@@ -465,22 +465,20 @@ limit ?"""
     ##########################################################################
 
     def answerCard(self, card: Card, ease: int) -> None:
-        self.col.log()
         assert 1 <= ease <= 4
         assert 0 <= card.queue <= 4
+
         self.col.markReview(card)
+
         if self._burySiblingsOnAnswer:
             self._burySiblings(card)
 
-        self._answerCard(card, ease)
+        new_state = self._answerCard(card, ease)
 
-        self._maybe_requeue_card(card)
+        if not self._handle_leech(card, new_state):
+            self._maybe_requeue_card(card)
 
-        card.mod = intTime()
+    def _answerCard(self, card: Card, ease: int) -> _pb.SchedulingState:
-        card.usn = self.col.usn()
-        card.flush()
-
-    def _answerCard(self, card: Card, ease: int) -> None:
         states = self.col._backend.get_next_card_states(card.id)
         if ease == BUTTON_ONE:
             new_state = states.again
@@ -509,6 +507,22 @@ limit ?"""
         # fixme: tests assume card will be mutated, so we need to reload it
         card.load()
 
+        return new_state
+
+    def _handle_leech(self, card: Card, new_state: _pb.SchedulingState) -> bool:
+        "True if was leech."
+        if self.col._backend.state_is_leech(new_state):
+            if hooks.card_did_leech.count() > 0:
+                hooks.card_did_leech(card)
+                # leech hooks assumed that card mutations would be saved for them
+                card.mod = intTime()
+                card.usn = self.col.usn()
+                card.flush()
+
+            return True
+        else:
+            return False
+
     def _maybe_requeue_card(self, card: Card) -> None:
         # preview cards
         if card.queue == QUEUE_TYPE_PREVIEW:
@@ -604,29 +618,6 @@ limit ?"""
 
         return self._interval_for_state(new_state)
 
-    # Leeches
-    ##########################################################################
-
-    def _checkLeech(self, card: Card, conf: QueueConfig) -> bool:
-        "Leech handler. True if card was a leech."
-        lf = conf["leechFails"]
-        if not lf:
-            return False
-        # if over threshold or every half threshold reps after that
-        if card.lapses >= lf and (card.lapses - lf) % (max(lf // 2, 1)) == 0:
-            # add a leech tag
-            f = card.note()
-            f.addTag("leech")
-            f.flush()
-            # handle
-            a = conf["leechAction"]
-            if a == LEECH_SUSPEND:
-                card.queue = QUEUE_TYPE_SUSPENDED
-            # notify UI
-            hooks.card_did_leech(card)
-            return True
-        return False
-
     # Sibling spacing
     ##########################################################################
 

pylib/rsbridge/lib.rs

@@ -54,6 +54,7 @@ fn want_release_gil(method: u32) -> bool {
                 | BackendMethod::JoinSearchNodes
                 | BackendMethod::ReplaceSearchNode
                 | BackendMethod::BuildSearchString
+                | BackendMethod::StateIsLeech
         )
     } else {
         false

pylib/tests/test_schedv2.py

@@ -405,6 +405,7 @@ def test_reviews():
     assert c.queue == QUEUE_TYPE_SUSPENDED
     c.load()
     assert c.queue == QUEUE_TYPE_SUSPENDED
+    assert "leech" in c.note().tags
 
 
 def test_review_limits():

rslib/backend.proto

@@ -117,6 +117,7 @@ service BackendService {
   rpc SortDeck(SortDeckIn) returns (Empty);
   rpc GetNextCardStates(CardID) returns (NextCardStates);
   rpc DescribeNextStates(NextCardStates) returns (StringList);
+  rpc StateIsLeech(SchedulingState) returns (Bool);
   rpc AnswerCard(AnswerCardIn) returns (Empty);
   rpc UpgradeScheduler(Empty) returns (Empty);
 
@@ -1283,6 +1284,7 @@ message SchedulingState {
     uint32 elapsed_days = 2;
     float ease_factor = 3;
     uint32 lapses = 4;
+    bool leeched = 5;
   }
   message Relearning {
     Review review = 1;

rslib/src/backend/generic.rs

@@ -15,6 +15,12 @@ impl From<String> for pb::String {
     }
 }
 
+impl From<bool> for pb::Bool {
+    fn from(val: bool) -> Self {
+        pb::Bool { val }
+    }
+}
+
 impl From<i64> for pb::Int64 {
     fn from(val: i64) -> Self {
         pb::Int64 { val }

rslib/src/backend/mod.rs

@@ -33,7 +33,7 @@ use crate::{
     sched::{
         new::NewCardSortOrder,
         parse_due_date_str,
-        states::NextCardStates,
+        states::{CardState, NextCardStates},
         timespan::{answer_button_time, time_span},
     },
     search::{
@@ -683,6 +683,11 @@ impl BackendService for Backend {
             .map(Into::into)
     }
 
+    fn state_is_leech(&self, input: pb::SchedulingState) -> BackendResult<pb::Bool> {
+        let state: CardState = input.into();
+        Ok(state.leeched().into())
+    }
+
     fn answer_card(&self, input: pb::AnswerCardIn) -> BackendResult<pb::Empty> {
         self.with_col(|col| col.answer_card(&input.into()))
             .map(Into::into)

rslib/src/backend/sched/states/review.rs

@@ -10,6 +10,7 @@ impl From<pb::scheduling_state::Review> for ReviewState {
             elapsed_days: state.elapsed_days,
             ease_factor: state.ease_factor,
             lapses: state.lapses,
+            leeched: state.leeched,
         }
     }
 }
@@ -21,6 +22,7 @@ impl From<ReviewState> for pb::scheduling_state::Review {
             elapsed_days: state.elapsed_days,
             ease_factor: state.ease_factor,
             lapses: state.lapses,
+            leeched: state.leeched,
         }
     }
 }

rslib/src/deckconf/schema11.rs

@@ -130,7 +130,7 @@ pub struct LapseConfSchema11 {
 
 impl Default for LeechAction {
     fn default() -> Self {
-        LeechAction::Suspend
+        LeechAction::TagOnly
     }
 }
 

rslib/src/notes.rs

@@ -32,7 +32,7 @@ pub(crate) struct TransformNoteOutput {
     pub mark_modified: bool,
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub struct Note {
     pub id: NoteID,
     pub guid: String,
@@ -467,6 +467,32 @@ impl Collection {
             Ok(DuplicateState::Empty)
         }
     }
+
+    /// Update the tags of the provided note, canonifying before save. Requires a transaction.
+    /// Fixme: this currently pulls in the note type, and does more work than necessary. We
+    /// could add a separate method to the storage layer to just update the tags in the future,
+    /// though  it does slightly complicate the undo story.
+    pub(crate) fn update_note_tags<F>(&mut self, nid: NoteID, mutator: F) -> Result<()>
+    where
+        F: Fn(&mut Vec<String>),
+    {
+        self.transform_notes(&[nid], |note, _nt| {
+            let mut tags = note.tags.clone();
+            mutator(&mut tags);
+            let changed = if tags != note.tags {
+                note.tags = tags;
+                true
+            } else {
+                false
+            };
+            Ok(TransformNoteOutput {
+                changed,
+                generate_cards: false,
+                mark_modified: true,
+            })
+        })
+        .map(|_| ())
+    }
 }
 
 #[cfg(test)]

rslib/src/sched/answering.rs

@@ -4,7 +4,7 @@
 use crate::{
     backend_proto,
     card::{CardQueue, CardType},
-    deckconf::DeckConf,
+    deckconf::{DeckConf, LeechAction},
     decks::{Deck, DeckKind},
     prelude::*,
     revlog::{RevlogEntry, RevlogReviewKind},
@@ -63,6 +63,7 @@ impl AnswerContext {
             easy_multiplier: self.config.inner.easy_multiplier,
             interval_multiplier: self.config.inner.interval_multiplier,
             maximum_review_interval: self.config.inner.maximum_review_interval,
+            leech_threshold: self.config.inner.leech_threshold,
             relearn_steps: self.relearn_steps(),
             lapse_multiplier: self.config.inner.lapse_multiplier,
             minimum_lapse_interval: self.config.inner.minimum_lapse_interval,
@@ -105,6 +106,7 @@ impl AnswerContext {
                     as u32,
                 ease_factor,
                 lapses,
+                leeched: false,
             }
             .into(),
             CardType::Relearn => RelearnState {
@@ -117,6 +119,7 @@ impl AnswerContext {
                     elapsed_days: interval,
                     ease_factor,
                     lapses,
+                    leeched: false,
                 },
             }
             .into(),
@@ -197,7 +200,7 @@ impl Card {
             self.original_due = 0;
         }
 
-        match next {
+        let revlog = match next {
             CardState::Normal(normal) => match normal {
                 NormalState::New(next) => self.apply_new_state(current, next, ctx),
                 NormalState::Learning(next) => self.apply_learning_state(current, next, ctx),
@@ -210,7 +213,13 @@ impl Card {
                     self.apply_rescheduling_state(current, next, ctx)
                 }
             },
+        }?;
+
+        if next.leeched() && ctx.config.inner.leech_action() == LeechAction::Suspend {
+            self.queue = CardQueue::Suspended;
         }
+
+        Ok(revlog)
     }
 
     fn apply_new_state(
@@ -386,6 +395,7 @@ pub struct RevlogEntryPartial {
 }
 
 impl RevlogEntryPartial {
+    /// Returns None in the Preview case, since preview cards do not currently log.
     fn maybe_new(
         current: CardState,
         next: CardState,
@@ -508,6 +518,9 @@ impl Collection {
             self.storage.add_revlog_entry(&revlog)?;
         }
         self.update_card(&mut card, &original, usn)?;
+        if answer.new_state.leeched() {
+            self.add_leech_tag(card.note_id)?;
+        }
 
         // fixme: we're reusing code used by python, which means re-feteching the target deck
         // - might want to avoid that in the future
@@ -556,6 +569,10 @@ impl Collection {
         let state_ctx = ctx.state_context();
         Ok(current.next_states(&state_ctx))
     }
+
+    fn add_leech_tag(&mut self, nid: NoteID) -> Result<()> {
+        self.update_note_tags(nid, |tags| tags.push("leech".into()))
+    }
 }
 
 /// Return a consistent seed for a given card at a given number of reps.

rslib/src/sched/states/filtered.rs

@@ -3,7 +3,9 @@
 
 use crate::revlog::RevlogReviewKind;
 
-use super::{IntervalKind, NextCardStates, PreviewState, ReschedulingFilterState, StateContext};
+use super::{
+    IntervalKind, NextCardStates, PreviewState, ReschedulingFilterState, ReviewState, StateContext,
+};
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum FilteredState {
@@ -32,4 +34,11 @@ impl FilteredState {
             FilteredState::Rescheduling(state) => state.next_states(ctx),
         }
     }
+
+    pub(crate) fn review_state(self) -> Option<ReviewState> {
+        match self {
+            FilteredState::Preview(state) => state.original_state.review_state(),
+            FilteredState::Rescheduling(state) => state.original_state.review_state(),
+        }
+    }
 }

rslib/src/sched/states/mod.rs

@@ -54,6 +54,18 @@ impl CardState {
             CardState::Filtered(state) => state.next_states(&ctx),
         }
     }
+
+    /// Returns underlying review state, if it exists.
+    pub(crate) fn review_state(self) -> Option<ReviewState> {
+        match self {
+            CardState::Normal(state) => state.review_state(),
+            CardState::Filtered(state) => state.review_state(),
+        }
+    }
+
+    pub(crate) fn leeched(self) -> bool {
+        self.review_state().map(|r| r.leeched).unwrap_or_default()
+    }
 }
 
 /// Info required during state transitions.
@@ -70,6 +82,7 @@ pub(crate) struct StateContext<'a> {
     pub easy_multiplier: f32,
     pub interval_multiplier: f32,
     pub maximum_review_interval: u32,
+    pub leech_threshold: u32,
 
     // relearning
     pub relearn_steps: LearningSteps<'a>,

rslib/src/sched/states/normal.rs

@@ -55,6 +55,15 @@ impl NormalState {
             NormalState::Relearning(state) => state.next_states(ctx),
         }
     }
+
+    pub(crate) fn review_state(self) -> Option<ReviewState> {
+        match self {
+            NormalState::New(_) => None,
+            NormalState::Learning(_) => None,
+            NormalState::Review(state) => Some(state),
+            NormalState::Relearning(RelearnState { review, .. }) => Some(review),
+        }
+    }
 }
 
 impl From<NewState> for NormalState {

rslib/src/sched/states/review.rs

@@ -19,6 +19,7 @@ pub struct ReviewState {
     pub elapsed_days: u32,
     pub ease_factor: f32,
     pub lapses: u32,
+    pub leeched: bool,
 }
 
 impl Default for ReviewState {
@@ -28,6 +29,7 @@ impl Default for ReviewState {
             elapsed_days: 0,
             ease_factor: INITIAL_EASE_FACTOR,
             lapses: 0,
+            leeched: false,
         }
     }
 }
@@ -71,11 +73,14 @@ impl ReviewState {
     }
 
     fn answer_again(self, ctx: &StateContext) -> CardState {
+        let lapses = self.lapses + 1;
+        let leeched = leech_threshold_met(lapses, ctx.leech_threshold);
         let again_review = ReviewState {
             scheduled_days: self.failing_review_interval(ctx),
             elapsed_days: 0,
             ease_factor: (self.ease_factor + EASE_FACTOR_AGAIN_DELTA).max(MINIMUM_EASE_FACTOR),
-            lapses: self.lapses + 1,
+            lapses,
+            leeched,
         };
 
         if let Some(again_delay) = ctx.relearn_steps.again_delay_secs_relearn() {
@@ -196,6 +201,18 @@ impl ReviewState {
     }
 }
 
+/// True when lapses is at threshold, or every half threshold after that.
+/// Non-even thresholds round up the half threshold.
+fn leech_threshold_met(lapses: u32, threshold: u32) -> bool {
+    if threshold > 0 {
+        let half_threshold = (threshold as f32 / 2.0).ceil().max(1.0) as u32;
+        // at threshold, and every half threshold after that, rounding up
+        lapses >= threshold && (lapses - threshold) % half_threshold == 0
+    } else {
+        false
+    }
+}
+
 /// Transform the provided hard/good/easy interval.
 /// - Apply configured interval multiplier.
 /// - Apply fuzz.
@@ -214,3 +231,37 @@ fn constrain_passing_interval(ctx: &StateContext, interval: f32, minimum: u32, f
         .min(ctx.maximum_review_interval)
         .max(1)
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn leech_threshold() {
+        assert_eq!(leech_threshold_met(0, 3), false);
+        assert_eq!(leech_threshold_met(1, 3), false);
+        assert_eq!(leech_threshold_met(2, 3), false);
+        assert_eq!(leech_threshold_met(3, 3), true);
+        assert_eq!(leech_threshold_met(4, 3), false);
+        assert_eq!(leech_threshold_met(5, 3), true);
+        assert_eq!(leech_threshold_met(6, 3), false);
+        assert_eq!(leech_threshold_met(7, 3), true);
+
+        assert_eq!(leech_threshold_met(7, 8), false);
+        assert_eq!(leech_threshold_met(8, 8), true);
+        assert_eq!(leech_threshold_met(9, 8), false);
+        assert_eq!(leech_threshold_met(10, 8), false);
+        assert_eq!(leech_threshold_met(11, 8), false);
+        assert_eq!(leech_threshold_met(12, 8), true);
+        assert_eq!(leech_threshold_met(13, 8), false);
+
+        // 0 means off
+        assert_eq!(leech_threshold_met(0, 0), false);
+
+        // no div by zero; half of 1 is 1
+        assert_eq!(leech_threshold_met(0, 1), false);
+        assert_eq!(leech_threshold_met(1, 1), true);
+        assert_eq!(leech_threshold_met(2, 1), true);
+        assert_eq!(leech_threshold_met(3, 1), true);
+    }
+}