Score for graph based ranking rules

Count phrases in matchingWords and maxMatchingWords

milli/src/search/new/graph_based_ranking_rule.rs

@@ -50,6 +50,7 @@ use super::ranking_rule_graph::{
 };
 use super::small_bitmap::SmallBitmap;
 use super::{QueryGraph, RankingRule, RankingRuleOutput, SearchContext};
+use crate::score_details::Rank;
 use crate::search::new::query_term::LocatedQueryTermSubset;
 use crate::search::new::ranking_rule_graph::PathVisitor;
 use crate::{Result, TermsMatchingStrategy};
@@ -118,6 +119,8 @@ pub struct GraphBasedRankingRuleState<G: RankingRuleGraphTrait> {
     all_costs: MappedInterner<QueryNode, Vec<u64>>,
     /// An index in the first element of `all_distances`, giving the cost of the next bucket
     cur_cost: u64,
+    /// One above the highest possible cost for this rule
+    next_max_cost: u64,
 }
 
 impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBasedRankingRule<G> {
@@ -131,7 +134,20 @@ impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBase
         _universe: &RoaringBitmap,
         query_graph: &QueryGraph,
     ) -> Result<()> {
+        // the `next_max_cost` is the successor integer to the maximum cost of the paths in the graph.
+        //
+        // When there is a matching strategy, it also factors the additional costs of:
+        // 1. The words that are matched in phrases
+        // 2. Skipping words (by adding them to the paths with a cost)
+        let mut next_max_cost = 1;
         let removal_cost = if let Some(terms_matching_strategy) = self.terms_matching_strategy {
+            // add the cost of the phrase to the next_max_cost
+            next_max_cost += query_graph
+                .words_in_phrases_count(ctx)
+                // remove 1 from the words in phrases count, because when there is a phrase we can now have a document
+                // where only the phrase is matching, and none of the non-phrase words.
+                // With the `1` that `next_max_cost` is initialized with, this gets counted twice.
+                .saturating_sub(1) as u64;
             match terms_matching_strategy {
                 TermsMatchingStrategy::Last => {
                     let removal_order =
@@ -161,12 +177,16 @@ impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBase
         // Then pre-compute the cost of all paths from each node to the end node
         let all_costs = graph.find_all_costs_to_end();
 
+        next_max_cost +=
+            all_costs.get(graph.query_graph.root_node).iter().copied().max().unwrap_or(0);
+
         let state = GraphBasedRankingRuleState {
             graph,
             conditions_cache: condition_docids_cache,
             dead_ends_cache,
             all_costs,
             cur_cost: 0,
+            next_max_cost,
         };
 
         self.state = Some(state);
@@ -180,17 +200,13 @@ impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBase
         logger: &mut dyn SearchLogger<QueryGraph>,
         universe: &RoaringBitmap,
     ) -> Result<Option<RankingRuleOutput<QueryGraph>>> {
-        // If universe.len() <= 1, the bucket sort algorithm
-        // should not have called this function.
-        assert!(universe.len() > 1);
         // Will crash if `next_bucket` is called before `start_iteration` or after `end_iteration`,
         // should never happen
         let mut state = self.state.take().unwrap();
 
+        let all_costs = state.all_costs.get(state.graph.query_graph.root_node);
         // Retrieve the cost of the paths to compute
-        let Some(&cost) = state
-            .all_costs
-            .get(state.graph.query_graph.root_node)
+        let Some(&cost) = all_costs
             .iter()
             .find(|c| **c >= state.cur_cost) else {
                 self.state = None;
@@ -206,8 +222,12 @@ impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBase
             dead_ends_cache,
             all_costs,
             cur_cost: _,
+            next_max_cost,
         } = &mut state;
 
+        let rank = *next_max_cost - cost;
+        let score = G::rank_to_score(Rank { rank: rank as u32, max_rank: *next_max_cost as u32 });
+
         let mut universe = universe.clone();
 
         let mut used_conditions = SmallBitmap::for_interned_values_in(&graph.conditions_interner);
@@ -322,7 +342,7 @@ impl<'ctx, G: RankingRuleGraphTrait> RankingRule<'ctx, QueryGraph> for GraphBase
 
         self.state = Some(state);
 
-        Ok(Some(RankingRuleOutput { query: next_query_graph, candidates: bucket }))
+        Ok(Some(RankingRuleOutput { query: next_query_graph, candidates: bucket, score }))
     }
 
     fn end_iteration(

milli/src/search/new/query_graph.rs

@@ -342,6 +342,25 @@ impl QueryGraph {
         }
         res
     }
+
+    /// Number of words in the phrases in this query graph
+    pub(crate) fn words_in_phrases_count(&self, ctx: &SearchContext) -> usize {
+        let mut word_count = 0;
+        for (_, node) in self.nodes.iter() {
+            match &node.data {
+                QueryNodeData::Term(term) => {
+                    let Some(phrase) = term.term_subset.original_phrase(ctx)
+                    else {
+                        continue
+                    };
+                    let phrase = ctx.phrase_interner.get(phrase);
+                    word_count += phrase.words.iter().copied().filter(|a| a.is_some()).count()
+                }
+                _ => continue,
+            }
+        }
+        word_count
+    }
 }
 
 fn add_node(nodes_data: &mut Vec<QueryNodeData>, node_data: QueryNodeData) -> u16 {