implement a first version of the stop_words

The front must provide a BTreeSet containing the stop words
The stop_words are set at None if an empty Set is provided
add the stop-words in the http-ui interface

Use maplit in the test
and remove all the useless drop(rtxn) at the end of all tests

http-ui/src/main.rs

@@ -1,4 +1,4 @@
-use std::collections::{BTreeMap, HashMap, HashSet};
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fmt::Display;
 use std::fs::{File, create_dir_all};
 use std::net::SocketAddr;
@@ -128,7 +128,10 @@ struct Highlighter<'a, A> {
 
 impl<'a, A: AsRef<[u8]>> Highlighter<'a, A> {
     fn new(stop_words: &'a fst::Set<A>) -> Self {
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
+        let mut config = AnalyzerConfig::default();
+        config.stop_words(stop_words);
+        let analyzer = Analyzer::new(config);
+
         Self { analyzer }
     }
 
@@ -266,6 +269,13 @@ struct Settings {
         skip_serializing_if = "Option::is_none",
     )]
     criteria: Option<Option<Vec<String>>>,
+
+    #[serde(
+        default,
+        deserialize_with = "deserialize_some",
+        skip_serializing_if = "Option::is_none",
+    )]
+    stop_words: Option<Option<BTreeSet<String>>>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -439,6 +449,14 @@ async fn main() -> anyhow::Result<()> {
                         }
                     }
 
+                    // We transpose the settings JSON struct into a real setting update.
+                    if let Some(stop_words) = settings.stop_words {
+                        match stop_words {
+                            Some(stop_words) => builder.set_stop_words(stop_words),
+                            None => builder.reset_stop_words(),
+                        }
+                    }
+
                     let result = builder.execute(|indexing_step, update_id| {
                         let (current, total) = match indexing_step {
                             TransformFromUserIntoGenericFormat { documents_seen } => (documents_seen, None),

milli/src/index.rs

@@ -28,6 +28,7 @@ pub const SEARCHABLE_FIELDS_KEY: &str = "searchable-fields";
 pub const HARD_EXTERNAL_DOCUMENTS_IDS_KEY: &str = "hard-external-documents-ids";
 pub const SOFT_EXTERNAL_DOCUMENTS_IDS_KEY: &str = "soft-external-documents-ids";
 pub const WORDS_FST_KEY: &str = "words-fst";
+pub const STOP_WORDS_KEY: &str = "stop-words";
 pub const WORDS_PREFIXES_FST_KEY: &str = "words-prefixes-fst";
 const CREATED_AT_KEY: &str = "created-at";
 const UPDATED_AT_KEY: &str = "updated-at";
@@ -377,6 +378,22 @@ impl Index {
         }
     }
 
+    /* stop words */
+
+    pub fn put_stop_words<A: AsRef<[u8]>>(&self, wtxn: &mut RwTxn, fst: &fst::Set<A>) -> heed::Result<()> {
+        self.main.put::<_, Str, ByteSlice>(wtxn, STOP_WORDS_KEY, fst.as_fst().as_bytes())
+    }
+
+    pub fn delete_stop_words(&self, wtxn: &mut RwTxn) -> heed::Result<bool> {
+        self.main.delete::<_, Str>(wtxn, STOP_WORDS_KEY)
+    }
+    pub fn stop_words<'t>(&self, rtxn: &'t RoTxn) -> anyhow::Result<Option<fst::Set<&'t [u8]>>> {
+        match self.main.get::<_, Str, ByteSlice>(rtxn, STOP_WORDS_KEY)? {
+            Some(bytes) => Ok(Some(fst::Set::new(bytes)?)),
+            None => Ok(None),
+        }
+    }
+
     /* words prefixes fst */
 
     /// Writes the FST which is the words prefixes dictionnary of the engine.

milli/src/search/mod.rs

@@ -4,7 +4,7 @@ use std::fmt;
 use std::str::Utf8Error;
 use std::time::Instant;
 
-use fst::{IntoStreamer, Streamer, Set};
+use fst::{IntoStreamer, Streamer};
 use levenshtein_automata::{DFA, LevenshteinAutomatonBuilder as LevBuilder};
 use log::debug;
 use meilisearch_tokenizer::{AnalyzerConfig, Analyzer};
@@ -91,8 +91,7 @@ impl<'a> Search<'a> {
                 let mut builder = QueryTreeBuilder::new(self.rtxn, self.index);
                 builder.optional_words(self.optional_words);
                 builder.authorize_typos(self.authorize_typos);
-                let stop_words = &Set::default();
+                let analyzer = Analyzer::<Vec<u8>>::new(AnalyzerConfig::default());
-                let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
                 let result = analyzer.analyze(query);
                 let tokens = result.tokens();
                 builder.build(tokens)?

milli/src/search/query_tree.rs

@@ -543,7 +543,6 @@ pub fn maximum_proximity(operation: &Operation) -> usize {
 mod test {
     use std::collections::HashMap;
 
-    use fst::Set;
     use maplit::{hashmap, hashset};
     use meilisearch_tokenizer::{Analyzer, AnalyzerConfig};
     use rand::{Rng, SeedableRng, rngs::StdRng};
@@ -646,8 +645,7 @@ mod test {
     #[test]
     fn prefix() {
         let query = "hey friends";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -667,8 +665,7 @@ mod test {
     #[test]
     fn no_prefix() {
         let query = "hey friends ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -688,8 +685,7 @@ mod test {
     #[test]
     fn synonyms() {
         let query = "hello world ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -720,8 +716,7 @@ mod test {
     #[test]
     fn complex_synonyms() {
         let query = "new york city ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -766,8 +761,7 @@ mod test {
     #[test]
     fn ngrams() {
         let query = "n grams ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -787,8 +781,7 @@ mod test {
     #[test]
     fn word_split() {
         let query = "wordsplit fish ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -814,8 +807,7 @@ mod test {
     #[test]
     fn phrase() {
         let query = "\"hey friends\" \" \" \"wooop";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -835,8 +827,7 @@ mod test {
     #[test]
     fn optional_word() {
         let query = "hey my friend ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -875,8 +866,7 @@ mod test {
     #[test]
     fn optional_word_phrase() {
         let query = "\"hey my\"";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -892,8 +882,7 @@ mod test {
     #[test]
     fn optional_word_multiple_phrases() {
         let query = r#""hey" my good "friend""#;
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -927,8 +916,7 @@ mod test {
     #[test]
     fn no_typo() {
         let query = "hey friends ";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 
@@ -947,8 +935,7 @@ mod test {
     #[test]
     fn fetching_words() {
         let query = "wordsplit nyc world";
-        let stop_words = &Set::default();
+        let analyzer = Analyzer::new(AnalyzerConfig::<Vec<u8>>::default());
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
         let result = analyzer.analyze(query);
         let tokens = result.tokens();
 

milli/src/update/index_documents/mod.rs

@@ -410,6 +410,8 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
             None => fields_ids_map.iter().map(|(id, _name)| id).collect(),
         };
 
+        let stop_words = self.index.stop_words(self.wtxn)?;
+        let stop_words = stop_words.as_ref();
         let linked_hash_map_size = self.linked_hash_map_size;
         let max_nb_chunks = self.max_nb_chunks;
         let max_memory = self.max_memory;
@@ -436,7 +438,6 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
             let readers = rayon::iter::repeatn(documents, num_threads)
                 .enumerate()
                 .map(|(i, documents)| {
-                    let stop_words = fst::Set::default();
                     let store = Store::new(
                         searchable_fields.clone(),
                         faceted_fields.clone(),
@@ -446,7 +447,7 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
                         chunk_compression_type,
                         chunk_compression_level,
                         chunk_fusing_shrink_size,
-                        &stop_words,
+                        stop_words,
                     )?;
                     store.index(
                         documents,

milli/src/update/index_documents/store.rs

@@ -86,7 +86,7 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
         chunk_compression_type: CompressionType,
         chunk_compression_level: Option<u32>,
         chunk_fusing_shrink_size: Option<u64>,
-        stop_words: &'s Set<A>,
+        stop_words: Option<&'s Set<A>>,
     ) -> anyhow::Result<Self>
     {
         // We divide the max memory by the number of sorter the Store have.
@@ -141,7 +141,11 @@ impl<'s, A: AsRef<[u8]>> Store<'s, A> {
             create_writer(chunk_compression_type, chunk_compression_level, f)
         })?;
 
-        let analyzer = Analyzer::new(AnalyzerConfig::default_with_stopwords(stop_words));
+        let mut config = AnalyzerConfig::default();
+        if let Some(stop_words) = stop_words {
+            config.stop_words(stop_words);
+        }
+        let analyzer = Analyzer::new(config);
 
         Ok(Store {
             // Indexing parameters.

milli/src/update/settings.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{BTreeSet, HashMap};
 use std::str::FromStr;
 
 use anyhow::Context;
@@ -32,6 +32,7 @@ pub struct Settings<'a, 't, 'u, 'i> {
     displayed_fields: Option<Option<Vec<String>>>,
     faceted_fields: Option<Option<HashMap<String, String>>>,
     criteria: Option<Option<Vec<String>>>,
+    stop_words: Option<Option<BTreeSet<String>>>,
 }
 
 impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
@@ -55,6 +56,7 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
             displayed_fields: None,
             faceted_fields: None,
             criteria: None,
+            stop_words: None,
             update_id,
         }
     }
@@ -91,6 +93,18 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.criteria = Some(Some(criteria));
     }
 
+    pub fn reset_stop_words(&mut self) {
+        self.stop_words = Some(None);
+    }
+
+    pub fn set_stop_words(&mut self, stop_words: BTreeSet<String>) {
+        self.stop_words = if stop_words.is_empty() {
+            Some(None)
+        } else {
+            Some(Some(stop_words))
+        }
+    }
+
     fn reindex<F>(&mut self, cb: &F, old_fields_ids_map: FieldsIdsMap) -> anyhow::Result<()>
     where
         F: Fn(UpdateIndexingStep, u64) + Sync
@@ -210,6 +224,28 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         Ok(true)
     }
 
+    fn update_stop_words(&mut self) -> anyhow::Result<bool> {
+        match self.stop_words {
+            Some(Some(ref stop_words)) => {
+                let current = self.index.stop_words(self.wtxn)?;
+                // since we can't compare a BTreeSet with an FST we are going to convert the
+                // BTreeSet to an FST and then compare bytes per bytes the two FSTs.
+                let fst = fst::Set::from_iter(&*stop_words)?;
+
+                // Does the new FST differ from the previous one?
+                if current.map_or(true, |current| current.as_fst().as_bytes() != fst.as_fst().as_bytes()) {
+                    // we want to re-create our FST.
+                    self.index.put_stop_words(self.wtxn, &fst)?;
+                    Ok(true)
+                } else {
+                    Ok(false)
+                }
+            }
+            Some(None) => Ok(self.index.delete_stop_words(self.wtxn)?),
+            None => Ok(false),
+        }
+    }
+
     fn update_facets(&mut self) -> anyhow::Result<bool> {
         match self.faceted_fields {
             Some(Some(ref fields)) => {
@@ -253,13 +289,14 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.index.set_updated_at(self.wtxn, &Utc::now())?;
         let old_fields_ids_map = self.index.fields_ids_map(&self.wtxn)?;
         self.update_displayed()?;
+        let stop_words_updated = self.update_stop_words()?;
         let facets_updated = self.update_facets()?;
         // update_criteria MUST be called after update_facets, since criterion fields must be set
         // as facets.
         self.update_criteria()?;
         let searchable_updated = self.update_searchable()?;
 
-            if facets_updated || searchable_updated {
+        if facets_updated || searchable_updated || stop_words_updated {
             self.reindex(&progress_callback, old_fields_ids_map)?;
         }
         Ok(())
@@ -271,7 +308,7 @@ mod tests {
     use super::*;
 
     use heed::EnvOpenOptions;
-    use maplit::hashmap;
+    use maplit::{hashmap, btreeset};
 
     use crate::facet::FacetType;
     use crate::update::{IndexDocuments, UpdateFormat};
@@ -328,7 +365,6 @@ mod tests {
         assert_eq!(result.documents_ids.len(), 1);
         let documents = index.documents(&rtxn, result.documents_ids).unwrap();
         assert_eq!(documents[0].1.get(0), Some(&br#""kevin""#[..]));
-        drop(rtxn);
     }
 
     #[test]
@@ -372,7 +408,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids.unwrap(), &["age"][..]);
-        drop(rtxn);
     }
 
     #[test]
@@ -394,7 +429,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids, None);
-        drop(rtxn);
     }
 
     #[test]
@@ -434,7 +468,6 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         let fields_ids = index.displayed_fields(&rtxn).unwrap();
         assert_eq!(fields_ids, None);
-        drop(rtxn);
     }
 
     #[test]
@@ -478,7 +511,96 @@ mod tests {
         // Only count the field_id 0 and level 0 facet values.
         let count = index.facet_field_id_value_docids.prefix_iter(&rtxn, &[0, 0]).unwrap().count();
         assert_eq!(count, 4);
-        drop(rtxn);
+    }
+
+    #[test]
+    fn default_stop_words() {
+        let path = tempfile::tempdir().unwrap();
+        let mut options = EnvOpenOptions::new();
+        options.map_size(10 * 1024 * 1024); // 10 MB
+        let index = Index::new(options, &path).unwrap();
+
+        // First we send 3 documents with ids from 1 to 3.
+        let mut wtxn = index.write_txn().unwrap();
+        let content = &b"name,age\nkevin,23\nkevina,21\nbenoit,34\n"[..];
+        let mut builder = IndexDocuments::new(&mut wtxn, &index, 0);
+        builder.update_format(UpdateFormat::Csv);
+        builder.execute(content, |_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        // Ensure there is no stop_words by default
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_none());
+    }
+
+    #[test]
+    fn set_and_reset_stop_words() {
+        let path = tempfile::tempdir().unwrap();
+        let mut options = EnvOpenOptions::new();
+        options.map_size(10 * 1024 * 1024); // 10 MB
+        let index = Index::new(options, &path).unwrap();
+
+        // First we send 3 documents with ids from 1 to 3.
+        let mut wtxn = index.write_txn().unwrap();
+        let content = &b"name,age,maxim\nkevin,23,I love dogs\nkevina,21,Doggos are the best\nbenoit,34,The crepes are really good\n"[..];
+        let mut builder = IndexDocuments::new(&mut wtxn, &index, 0);
+        builder.update_format(UpdateFormat::Csv);
+        builder.execute(content, |_, _| ()).unwrap();
+
+        // In the same transaction we provide some stop_words
+        let mut builder = Settings::new(&mut wtxn, &index, 0);
+        let set = btreeset!{ "i".to_string(), "the".to_string(), "are".to_string() };
+        builder.set_stop_words(set.clone());
+        builder.execute(|_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        // Ensure stop_words are effectively stored
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_some()); // at this point the index should return something
+
+        let stop_words = stop_words.unwrap();
+        let expected = fst::Set::from_iter(&set).unwrap();
+        assert_eq!(stop_words.as_fst().as_bytes(), expected.as_fst().as_bytes());
+
+        // when we search for something that is a non prefix stop_words it should be ignored
+        let result = index.search(&rtxn).query("the ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+        let result = index.search(&rtxn).query("i ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+        let result = index.search(&rtxn).query("are ").execute().unwrap();
+        assert!(result.documents_ids.is_empty());
+
+        let result = index.search(&rtxn).query("dog").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2); // we have two maxims talking about doggos
+        let result = index.search(&rtxn).query("benoît").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1); // there is one benoit in our data
+
+        // now we'll reset the stop_words and ensure it's None
+        let mut wtxn = index.write_txn().unwrap();
+        let mut builder = Settings::new(&mut wtxn, &index, 0);
+        builder.reset_stop_words();
+        builder.execute(|_, _| ()).unwrap();
+        wtxn.commit().unwrap();
+
+        let rtxn = index.read_txn().unwrap();
+        let stop_words = index.stop_words(&rtxn).unwrap();
+        assert!(stop_words.is_none());
+
+        // now we can search for the stop words
+        let result = index.search(&rtxn).query("the").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2);
+        let result = index.search(&rtxn).query("i").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1);
+        let result = index.search(&rtxn).query("are").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2);
+
+        // the rest of the search is still not impacted
+        let result = index.search(&rtxn).query("dog").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 2); // we have two maxims talking about doggos
+        let result = index.search(&rtxn).query("benoît").execute().unwrap();
+        assert_eq!(result.documents_ids.len(), 1); // there is one benoit in our data
     }
 
     #[test]
@@ -519,6 +641,5 @@ mod tests {
         assert_eq!(&["hello"][..], index.displayed_fields(&rtxn).unwrap().unwrap());
         assert!(index.primary_key(&rtxn).unwrap().is_none());
         assert_eq!(vec![Criterion::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
-        drop(rtxn);
     }
 }