perf(channel): avoid unnecessary allocations

benches/main/ui.rs

@@ -498,7 +498,8 @@ pub fn draw(c: &mut Criterion) {
                     std::thread::sleep(std::time::Duration::from_millis(10));
                 }
                 tv.move_cursor(Movement::Next, 10);
-                let _ = tv.update_preview_state(&tv.get_selected_entry());
+                let selected_entry = tv.get_selected_entry();
+                let _ = tv.update_preview_state(&selected_entry);
                 let _ = tv.update(&Action::Tick);
                 (tv, terminal)
             },

television/channels/channel.rs

@@ -107,7 +107,7 @@ impl Channel {
         entries
     }
 
-    pub fn get_result(&self, index: u32) -> Option<Entry> {
+    pub fn get_result(&mut self, index: u32) -> Option<Entry> {
         if let Some(item) = self.matcher.get_result(index) {
             let mut entry = Entry::new(item.inner.clone())
                 .with_display(item.matched_string)
@@ -177,6 +177,8 @@ impl Channel {
     }
 }
 
+const DEFAULT_LINE_BUFFER_SIZE: usize = 512;
+
 #[allow(clippy::unused_async)]
 async fn load_candidates(
     source: SourceSpec,
@@ -197,7 +199,7 @@ async fn load_candidates(
     if let Some(out) = child.stdout.take() {
         let mut produced_output = false;
         let mut reader = BufReader::new(out);
-        let mut buf = Vec::new();
+        let mut buf = Vec::with_capacity(DEFAULT_LINE_BUFFER_SIZE);
 
         let delimiter = source
             .entry_delimiter

television/channels/remote_control.rs

@@ -155,7 +155,7 @@ impl RemoteControl {
             .collect()
     }
 
-    pub fn get_result(&self, index: u32) -> CableEntry {
+    pub fn get_result(&mut self, index: u32) -> CableEntry {
         let item = self.matcher.get_result(index).expect("Invalid index");
         item.inner.with_match_indices(&item.match_indices)
     }

television/matcher/mod.rs

@@ -226,23 +226,23 @@ where
     /// }
     /// ```
     pub fn get_result(
-        &self,
+        &mut self,
         index: u32,
     ) -> Option<matched_item::MatchedItem<I>> {
         let snapshot = self.inner.snapshot();
-        let mut col_indices = Vec::new();
         let mut matcher = lazy::MATCHER.lock();
+        self.col_indices_buffer.clear();
 
         snapshot.get_matched_item(index).map(|item| {
             snapshot.pattern().column_pattern(0).indices(
                 item.matcher_columns[0].slice(..),
                 &mut matcher,
-                &mut col_indices,
+                &mut self.col_indices_buffer,
             );
-            col_indices.sort_unstable();
+            self.col_indices_buffer.sort_unstable();
-            col_indices.dedup();
+            self.col_indices_buffer.dedup();
 
-            let indices = col_indices.drain(..);
+            let indices = self.col_indices_buffer.drain(..);
             let matched_string = item.matcher_columns[0].to_string();
 
             matched_item::MatchedItem {

television/television.rs

@@ -389,7 +389,7 @@ impl Television {
         }
     }
 
-    pub fn get_selected_entry(&self) -> Option<Entry> {
+    pub fn get_selected_entry(&mut self) -> Option<Entry> {
         if self.channel.result_count() == 0 {
             return None;
         }
@@ -398,7 +398,7 @@ impl Television {
             .and_then(|entry| entry)
     }
 
-    pub fn get_selected_cable_entry(&self) -> Option<CableEntry> {
+    pub fn get_selected_cable_entry(&mut self) -> Option<CableEntry> {
         if self
             .remote_control
             .as_ref()
@@ -408,7 +408,7 @@ impl Television {
             return None;
         }
         self.selected_index().and_then(|idx| {
-            self.remote_control.as_ref().map(|rc| rc.get_result(idx))
+            self.remote_control.as_mut().map(|rc| rc.get_result(idx))
         })
     }
 
@@ -423,7 +423,7 @@ impl Television {
     }
 
     #[must_use]
-    pub fn get_selected_entries(&self) -> Option<FxHashSet<Entry>> {
+    pub fn get_selected_entries(&mut self) -> Option<FxHashSet<Entry>> {
         // if nothing is selected, return the currently hovered entry
         if self.channel.selected_entries().is_empty() {
             return self