perf(fuzzy): match only the previous results when the query gets longer

crates/fff-core/benches/fuzzy_search_bench.rs

@@ -1,4 +1,4 @@
-use criterion::{BenchmarkId, Criterion, criterion_group, criterion_main};
+use criterion::{BatchSize, BenchmarkId, Criterion, criterion_group, criterion_main};
 use fff_search::{FilePicker, FilePickerOptions, FuzzySearchOptions, PaginationArgs, QueryParser};
 use std::{hint::black_box, time::Duration};
 
@@ -87,6 +87,31 @@ fn bench_picker(
             });
         }
     }
+    // Measure the same final keystroke, with and without a reusable prefix.
+    let parsed = parser.parse("group_57/controller_570");
+    let options = FuzzySearchOptions {
+        max_threads: 4,
+        pagination: PaginationArgs {
+            offset: 0,
+            limit: 50,
+        },
+        ..Default::default()
+    };
+    for (name, previous) in [
+        ("cold", "unrelated_query"),
+        ("warm", "group_57/controller_57"),
+    ] {
+        let previous = parser.parse(previous);
+        group.bench_function(BenchmarkId::new("incremental", name), |b| {
+            b.iter_batched(
+                || {
+                    black_box(picker.fuzzy_search(&previous, None, options));
+                },
+                |()| black_box(picker.fuzzy_search(&parsed, None, options)),
+                BatchSize::PerIteration,
+            );
+        });
+    }
     group.finish();
 }
 

crates/fff-core/src/file_picker.rs

@@ -39,7 +39,9 @@ use crate::index::layers::{LayerArenas, LayerId, LayerStack, SESSION_LAYER};
 use crate::index::{BigramFilter, BigramOverlay};
 use crate::query_tracker::QueryTracker;
 use crate::scan::{ScanConfig, ScanJob, ScanSignals};
-use crate::score::{fuzzy_match_and_score_files, fuzzy_match_byte_offsets_for_page};
+use crate::score::{
+    FuzzyMatchCache, fuzzy_match_and_score_files, fuzzy_match_byte_offsets_for_page,
+};
 use crate::shared::{SharedFilePicker, SharedFrecency};
 use crate::simd_path::ArenaPtr;
 use crate::stable_vec::StableVec;
@@ -728,6 +730,8 @@ pub struct FilePicker {
     enable_fs_root_scanning: bool,
     enable_home_dir_scanning: bool,
     git_recency_config: GitRecencyConfig,
+    // Cleared whenever files are added, restored or replaced.
+    fuzzy_cache: parking_lot::Mutex<Option<FuzzyMatchCache>>,
     trace_span: tracing::Span,
     trace_id: String,
 }
@@ -873,6 +877,7 @@ impl FilePicker {
     }
 
     pub fn get_file_mut(&mut self, index: usize) -> Option<(ArenaPtr, &mut FileItem)> {
+        *self.fuzzy_cache.get_mut() = None;
         self.sync_data.get_file_mut(index)
     }
 
@@ -1113,6 +1118,7 @@ impl FilePicker {
             enable_fs_root_scanning: options.enable_fs_root_scanning,
             enable_home_dir_scanning: options.enable_home_dir_scanning,
             git_recency_config: options.git_recency,
+            fuzzy_cache: parking_lot::Mutex::new(None),
             trace_span,
             trace_id,
         })
@@ -1366,13 +1372,16 @@ impl FilePicker {
         let arenas = self.sync_data.layer_arenas();
         let overlay_ranges = self.sync_data.layers.file_ranges(files.len());
 
+        let mut cache = self.fuzzy_cache.lock().take();
         let (items, scores, total_matched) = fuzzy_match_and_score_files(
             files,
             &context,
             self.sync_data.base_count,
             arenas,
             &overlay_ranges,
+            &mut cache,
         );
+        *self.fuzzy_cache.lock() = cache;
         let match_byte_offsets =
             fuzzy_match_byte_offsets_for_page(query, &items, max_typos, arenas);
 
@@ -1751,6 +1760,7 @@ impl FilePicker {
         self.cache_budget.reset();
         let mut previous = std::mem::replace(&mut self.sync_data, sync);
         self.sync_data.adopt_overlays(&mut previous);
+        *self.fuzzy_cache.get_mut() = None;
         previous
     }
 
@@ -1894,7 +1904,7 @@ impl FilePicker {
     ) -> Option<(ArenaPtr, &mut FileItem)> {
         let path = path.as_ref();
         let index = self.sync_data.find_file_index(path, &self.base_path);
-        index.and_then(|i| self.sync_data.get_file_mut(i))
+        index.and_then(|i| self.get_file_mut(i))
     }
 
     /// Handle the event of certain file being modified or adds a neww file if it is not added
@@ -2018,6 +2028,8 @@ impl FilePicker {
         self.sync_data.ensure_capacity(0, 1);
         let parent_dir = self.sync_data.find_or_add_dir(&dir_rel)?;
 
+        *self.fuzzy_cache.get_mut() = None;
+
         let chunked = self
             .sync_data
             .layers

crates/fff-core/src/file_picker/layer_ops.rs

@@ -602,6 +602,7 @@ impl FilePicker {
     /// overlays exist and [`Error::IndexBusy`] during a scan or post-scan indexing.
     pub fn create_layer(&mut self, label: Option<&str>) -> Result<LayerId, Error> {
         self.ensure_index_idle()?;
+        *self.fuzzy_cache.get_mut() = None;
         let id = self.sync_data.create_layer(label)?;
         debug!(layer = id, ?label, "Opened new index layer");
 
@@ -666,6 +667,7 @@ impl FilePicker {
     ) -> Result<usize, Error> {
         let entries: Vec<IndexEntry<'a>> = entries.into_iter().collect();
         self.reserve_index(entries.len(), entries.len())?;
+        *self.fuzzy_cache.get_mut() = None;
         let added = self.sync_data.add_entries(&entries)?;
         debug!(
             added,
@@ -685,6 +687,7 @@ impl FilePicker {
         self.ensure_index_idle()?;
         let id = self.sync_data.layers.free_id().ok_or(Error::LayerLimit)?;
         self.reserve_index(snapshot.files.len(), snapshot.dirs.len())?;
+        *self.fuzzy_cache.get_mut() = None;
         let added = self.sync_data.attach_snapshot(id, snapshot, Attach::Import);
         info!(layer = id, added, "Imported index layer");