Fix more bugs + visual empty path cache logging

milli/src/search/new/graph_based_ranking_rule.rs

@@ -71,12 +71,13 @@ impl<'transaction, G: RankingRuleGraphTrait> RankingRule<'transaction, QueryGrap
         assert!(universe.len() > 1);
         let mut state = self.state.take().unwrap();
 
-        let Some(cheapest_paths_state) = state.cheapest_paths_state.take() else {
+        let Some(mut cheapest_paths_state) = state.cheapest_paths_state.take() else {
             return Ok(None);
         };
 
         let mut paths = PathsMap::default();
 
+        while paths.is_empty() {
             if let Some(next_cheapest_paths_state) = cheapest_paths_state
                 .compute_paths_of_next_lowest_cost(
                     &mut state.graph,
@@ -84,17 +85,15 @@ impl<'transaction, G: RankingRuleGraphTrait> RankingRule<'transaction, QueryGrap
                     &mut paths,
                 )
             {
-            state.cheapest_paths_state = Some(next_cheapest_paths_state);
+                cheapest_paths_state = next_cheapest_paths_state;
             } else {
-            state.cheapest_paths_state = None;
-        }
-
-        if paths.is_empty() {
                 self.state = None;
                 return Ok(None);
             }
+        }
+        state.cheapest_paths_state = Some(cheapest_paths_state);
 
-        G::log_state(&state.graph, &paths, logger);
+        G::log_state(&state.graph, &paths, &state.empty_paths_cache, logger);
 
         let bucket = state.graph.resolve_paths(
             index,

milli/src/search/new/logger/detailed.rs

@@ -6,6 +6,7 @@ use std::{io::Write, path::PathBuf};
 
 use crate::new::QueryNode;
 use crate::new::query_term::{LocatedQueryTerm, QueryTerm, WordDerivations};
+use crate::new::ranking_rule_graph::empty_paths_cache::EmptyPathsCache;
 use crate::new::ranking_rule_graph::{Edge, EdgeDetails, RankingRuleGraphTrait};
 use crate::new::ranking_rule_graph::{
     paths_map::PathsMap, proximity::ProximityGraph, RankingRuleGraph,
@@ -36,6 +37,7 @@ pub enum SearchEvents {
     ProximityState {
         graph: RankingRuleGraph<ProximityGraph>,
         paths: PathsMap<u64>,
+        empty_paths_cache: EmptyPathsCache,
     },
 }
 
@@ -107,16 +109,16 @@ impl SearchLogger<QueryGraph> for DetailedSearchLogger {
             universe: universe.clone(),
         })
     }
-    fn add_to_results(&mut self, docids: &RoaringBitmap) {
+    fn add_to_results(&mut self, docids: &mut dyn Iterator<Item = u32>) {
-        self.events.push(SearchEvents::ExtendResults { new: docids.clone() });
+        self.events.push(SearchEvents::ExtendResults { new: docids.collect() });
     }
 
     fn log_words_state(&mut self, query_graph: &QueryGraph) {
         self.events.push(SearchEvents::WordsState { query_graph: query_graph.clone() });
     }
 
-    fn log_proximity_state(&mut self, query_graph: &RankingRuleGraph<ProximityGraph>, paths_map: &PathsMap<u64>,) {
+    fn log_proximity_state(&mut self, query_graph: &RankingRuleGraph<ProximityGraph>, paths_map: &PathsMap<u64>, empty_paths_cache: &EmptyPathsCache) {
-        self.events.push(SearchEvents::ProximityState { graph: query_graph.clone(), paths: paths_map.clone() })
+        self.events.push(SearchEvents::ProximityState { graph: query_graph.clone(), paths: paths_map.clone(), empty_paths_cache: empty_paths_cache.clone() })
     }
     
     
@@ -224,13 +226,13 @@ results.{random} {{
     link: \"{id}.d2.svg\"
 }}").unwrap();
                 },
-                SearchEvents::ProximityState { graph, paths } => {
+                SearchEvents::ProximityState { graph, paths, empty_paths_cache } => {
                     let cur_ranking_rule = timestamp.len() - 1;
                     let cur_activated_id = activated_id(&timestamp);
                     let id = format!("{cur_ranking_rule}.{cur_activated_id}");
                     let mut new_file_path = self.folder_path.join(format!("{id}.d2"));
                     let mut new_file = std::fs::File::create(new_file_path).unwrap();
-                    Self::proximity_graph_d2_description(graph, paths, &mut new_file);
+                    Self::proximity_graph_d2_description(graph, paths, empty_paths_cache, &mut new_file);
                     writeln!(
                         &mut file,
                         "{id} {{
@@ -288,7 +290,7 @@ shape: class").unwrap();
             }
         }        
     }
-    fn proximity_graph_d2_description(graph: &RankingRuleGraph<ProximityGraph>, paths: &PathsMap<u64>, file: &mut File) {
+    fn proximity_graph_d2_description(graph: &RankingRuleGraph<ProximityGraph>, paths: &PathsMap<u64>, empty_paths_cache: &EmptyPathsCache, file: &mut File) {
         writeln!(file,"direction: right").unwrap();
 
         writeln!(file, "Proximity Graph {{").unwrap();
@@ -322,11 +324,19 @@ shape: class").unwrap();
         writeln!(file, "Shortest Paths {{").unwrap();
         Self::paths_d2_description(graph, "", paths, file);
         writeln!(file, "}}").unwrap();
-    }
-    fn paths_d2_description(graph: &RankingRuleGraph<ProximityGraph>, paths_idx: &str, paths: &PathsMap<u64>, file: &mut File) { 
 
-        for (edge_idx, rest) in paths.nodes.iter() {
+        writeln!(file, "Empty Path Prefixes {{").unwrap();
-            let Edge { from_node, to_node, cost, .. } = graph.all_edges[*edge_idx as usize].as_ref().unwrap() ;
+        Self::paths_d2_description(graph, "", &empty_paths_cache.empty_prefixes, file);
+        writeln!(file, "}}").unwrap();
+
+        writeln!(file, "Removed Edges {{").unwrap();
+        for edge_idx in empty_paths_cache.empty_edges.iter() {
+            writeln!(file, "{edge_idx}").unwrap();
+        }
+        writeln!(file, "}}").unwrap();
+    }
+    fn edge_d2_description(graph: &RankingRuleGraph<ProximityGraph>, paths_idx: &str, edge_idx: u32, file: &mut File) -> String {
+        let Edge { from_node, to_node, cost, .. } = graph.all_edges[edge_idx as usize].as_ref().unwrap() ;
         let from_node = &graph.query_graph.nodes[*from_node as usize];
         let from_node_desc = match from_node {
             QueryNode::Term(term) => match &term.value {
@@ -351,6 +361,11 @@ shape: class").unwrap();
         writeln!(file, "{edge_id}: \"{from_node_desc}->{to_node_desc} [{cost}]\" {{
             shape: class
         }}").unwrap();
+        edge_id
+    }
+    fn paths_d2_description<T>(graph: &RankingRuleGraph<ProximityGraph>, paths_idx: &str, paths: &PathsMap<T>, file: &mut File) { 
+        for (edge_idx, rest) in paths.nodes.iter() {
+            let edge_id = Self::edge_d2_description(graph, paths_idx, *edge_idx, file);
             for (dest_edge_idx, _) in rest.nodes.iter() {
                 let dest_edge_id = format!("{paths_idx}{edge_idx}{dest_edge_idx}");
                 writeln!(file, "{edge_id} -> {dest_edge_id}").unwrap();

milli/src/search/new/logger/mod.rs

@@ -5,7 +5,10 @@ use roaring::RoaringBitmap;
 
 use super::{
     query_graph,
-    ranking_rule_graph::{paths_map::PathsMap, proximity::ProximityGraph, RankingRuleGraph},
+    ranking_rule_graph::{
+        empty_paths_cache::EmptyPathsCache, paths_map::PathsMap, proximity::ProximityGraph,
+        RankingRuleGraph,
+    },
     QueryGraph, RankingRule, RankingRuleQueryTrait,
 };
 
@@ -41,7 +44,7 @@ impl<Q: RankingRuleQueryTrait> SearchLogger<Q> for DefaultSearchLogger {
     ) {
     }
 
-    fn add_to_results(&mut self, docids: &RoaringBitmap) {}
+    fn add_to_results(&mut self, docids: &mut dyn Iterator<Item = u32>) {}
 
     fn log_words_state(&mut self, query_graph: &Q) {}
 
@@ -49,6 +52,7 @@ impl<Q: RankingRuleQueryTrait> SearchLogger<Q> for DefaultSearchLogger {
         &mut self,
         query_graph: &RankingRuleGraph<ProximityGraph>,
         paths_map: &PathsMap<u64>,
+        empty_paths_cache: &EmptyPathsCache,
     ) {
     }
 }
@@ -78,7 +82,7 @@ pub trait SearchLogger<Q: RankingRuleQueryTrait> {
         ranking_rule: &dyn RankingRule<'transaction, Q>,
         universe: &RoaringBitmap,
     );
-    fn add_to_results(&mut self, docids: &RoaringBitmap);
+    fn add_to_results(&mut self, docids: &mut dyn Iterator<Item = u32>);
 
     fn log_words_state(&mut self, query_graph: &Q);
 
@@ -86,5 +90,6 @@ pub trait SearchLogger<Q: RankingRuleQueryTrait> {
         &mut self,
         query_graph: &RankingRuleGraph<ProximityGraph>,
         paths: &PathsMap<u64>,
+        empty_paths_cache: &EmptyPathsCache,
     );
 }

milli/src/search/new/ranking_rule_graph/cheapest_paths.rs

@@ -81,7 +81,9 @@ impl KCheapestPathsState {
         while self.kth_cheapest_path.cost <= cur_cost {
             if let Some(next_self) = self.compute_next_cheapest_paths(graph, empty_paths_cache) {
                 self = next_self;
-                if self.kth_cheapest_path.cost == cur_cost {
+                if self.kth_cheapest_path.cost == cur_cost
+                    && !empty_paths_cache.path_is_empty(&self.kth_cheapest_path.edges)
+                {
                     into_map.add_path(&self.kth_cheapest_path);
                 } else {
                     break;
@@ -148,7 +150,13 @@ impl KCheapestPathsState {
 
             while let Some((next_cheapest_path, cost2)) = next_cheapest_paths.remove_first() {
                 assert_eq!(cost, cost2);
-                if empty_paths_cache.path_is_empty(&next_cheapest_path) {
+                // NOTE: it is important not to discard the paths that are forbidden due to a
+                // forbidden prefix, because the cheapest path algorithm (Dijkstra) cannot take
+                // this property into account.
+                if next_cheapest_path
+                    .iter()
+                    .any(|edge_index| graph.all_edges[*edge_index as usize].is_none())
+                {
                     continue;
                 } else {
                     self.cheapest_paths.insert(next_cheapest_path.iter().copied(), cost);

milli/src/search/new/ranking_rule_graph/empty_paths_cache.rs

@@ -4,12 +4,16 @@ use roaring::RoaringBitmap;
 
 use super::paths_map::PathsMap;
 
-#[derive(Default)]
+#[derive(Default, Clone)]
 pub struct EmptyPathsCache {
     pub empty_edges: RoaringBitmap,
     pub empty_prefixes: PathsMap<()>,
 }
 impl EmptyPathsCache {
+    pub fn forbid_edge(&mut self, edge_idx: u32) {
+        self.empty_edges.insert(edge_idx);
+        self.empty_prefixes.remove_edge(&edge_idx);
+    }
     pub fn path_is_empty(&self, path: &[u32]) -> bool {
         for edge in path {
             if self.empty_edges.contains(*edge) {

milli/src/search/new/ranking_rule_graph/mod.rs

@@ -11,6 +11,7 @@ use std::ops::ControlFlow;
 use heed::RoTxn;
 use roaring::RoaringBitmap;
 
+use self::empty_paths_cache::EmptyPathsCache;
 use self::paths_map::PathsMap;
 
 use super::db_cache::DatabaseCache;
@@ -82,6 +83,7 @@ pub trait RankingRuleGraphTrait: Sized {
     fn log_state(
         graph: &RankingRuleGraph<Self>,
         paths: &PathsMap<u64>,
+        empty_paths_cache: &EmptyPathsCache,
         logger: &mut dyn SearchLogger<QueryGraph>,
     );
 }

milli/src/search/new/ranking_rule_graph/proximity/mod.rs

@@ -3,6 +3,7 @@ pub mod compute_docids;
 
 use heed::RoTxn;
 
+use super::empty_paths_cache::EmptyPathsCache;
 use super::paths_map::PathsMap;
 use super::{Edge, EdgeDetails, RankingRuleGraphTrait};
 use crate::new::db_cache::DatabaseCache;
@@ -67,8 +68,9 @@ impl RankingRuleGraphTrait for ProximityGraph {
     fn log_state(
         graph: &super::RankingRuleGraph<Self>,
         paths: &PathsMap<u64>,
+        empty_paths_cache: &EmptyPathsCache,
         logger: &mut dyn crate::new::logger::SearchLogger<crate::new::QueryGraph>,
     ) {
-        logger.log_proximity_state(graph, paths);
+        logger.log_proximity_state(graph, paths, empty_paths_cache);
     }
 }

milli/src/search/new/ranking_rule_graph/resolve_paths.rs

@@ -40,7 +40,7 @@ impl<G: RankingRuleGraphTrait> RankingRuleGraph<G> {
                     BitmapOrAllRef::Bitmap(edge_docids) => {
                         if edge_docids.is_disjoint(universe) {
                             // 1. Store in the cache that this edge is empty for this universe
-                            empty_paths_cache.empty_edges.insert(edge_index);
+                            empty_paths_cache.forbid_edge(edge_index);
                             // 2. remove all the paths that contain this edge for this universe
                             paths.remove_edge(&edge_index);
                             // 3. remove this edge from the proximity graph

milli/src/search/new/ranking_rules.rs

@@ -139,6 +139,7 @@ pub fn execute_search<'transaction>(
     candidates[0] = universe.clone();
 
     let mut cur_ranking_rule_index = 0;
+
     macro_rules! back {
         () => {
             logger.end_iteration_ranking_rule(
@@ -157,13 +158,20 @@ pub fn execute_search<'transaction>(
     }
 
     let mut results = vec![];
+    macro_rules! add_to_results {
+        ($candidates:expr) => {
+            logger.add_to_results(&mut $candidates.iter().take(20 - results.len()));
+            let iter = $candidates.iter().take(20 - results.len());
+            results.extend(iter);
+        };
+    }
+
     // TODO: skip buckets when we want to start from an offset
     while results.len() < 20 {
         // The universe for this bucket is zero or one element, so we don't need to sort
         // anything, just extend the results and go back to the parent ranking rule.
         if candidates[cur_ranking_rule_index].len() <= 1 {
-            logger.add_to_results(&candidates[cur_ranking_rule_index]);
+            add_to_results!(candidates[cur_ranking_rule_index]);
-            results.extend(&candidates[cur_ranking_rule_index]);
             back!();
             continue;
         }
@@ -183,15 +191,12 @@ pub fn execute_search<'transaction>(
 
         if next_bucket.candidates.len() <= 1 {
             // Only zero or one candidate, no need to sort through the child ranking rule.
-            logger.add_to_results(&next_bucket.candidates);
+            add_to_results!(next_bucket.candidates);
-            results.extend(next_bucket.candidates);
             continue;
         } else {
             // many candidates, give to next ranking rule, if any
             if cur_ranking_rule_index == ranking_rules_len - 1 {
-                // TODO: don't extend too much, up to the limit only
+                add_to_results!(next_bucket.candidates);
-                logger.add_to_results(&next_bucket.candidates);
-                results.extend(next_bucket.candidates);
             } else {
                 cur_ranking_rule_index += 1;
                 candidates[cur_ranking_rule_index] = next_bucket.candidates.clone();
@@ -313,8 +318,7 @@ mod tests {
         let mut db_cache = DatabaseCache::default();
 
         let query_graph =
-            make_query_graph(&index, &txn, &mut db_cache, "the sun flower is facing the su")
+            make_query_graph(&index, &txn, &mut db_cache, "a a a a a a a a a a").unwrap();
-                .unwrap();
 
         // TODO: filters + maybe distinct attributes?
         let universe = get_start_universe(