improve performance of long error list

src/app.rs

@@ -28,10 +28,8 @@ impl<'logs> App<'logs> {
             .find_lines(move |line| line.request_id == request_id)
     }
 
-    pub fn error_lines(&self) -> impl Iterator<Item = (&'logs str, &'logs JsonError)> + use<'logs> {
-        self.lines.errors().iter().map(|(line_number, error)| {
-            (self.log_file.nth(*line_number).unwrap_or_default(), error)
-        })
+    pub fn error_lines<'a>(&'a self) -> &'a [(&'logs str, JsonError)] {
+        self.lines.errors()
     }
 
     pub fn error_count(&self) -> usize {

src/logs.rs

@@ -1,4 +1,4 @@
-use crate::logfile::{LogLine, LogLineNumber};
+use crate::logfile::LogLine;
 use serde::Deserialize;
 use serde_json::Error as JsonError;
 use std::ops::Index;
@@ -21,14 +21,14 @@ impl From<&usize> for LogIndex {
 
 pub struct ParsedLogs<'logfile> {
     parsed: Vec<LogLine<'logfile>>,
-    error_lines: Vec<(LogLineNumber, JsonError)>,
+    error_lines: Vec<(&'logfile str, JsonError)>,
 }
 
 impl<'logfile> ParsedLogs<'logfile> {
     pub fn all(&self) -> &[LogLine<'logfile>] {
         &self.parsed
     }
-    pub fn errors(&self) -> &[(LogLineNumber, JsonError)] {
+    pub fn errors(&self) -> &[(&'logfile str, JsonError)] {
         &self.error_lines
     }
 
@@ -48,8 +48,8 @@ impl<'logfile> ParsedLogs<'logfile> {
     }
 }
 
-impl<'a> FromIterator<Result<LogLine<'a>, (LogLineNumber, JsonError)>> for ParsedLogs<'a> {
-    fn from_iter<T: IntoIterator<Item = Result<LogLine<'a>, (LogLineNumber, JsonError)>>>(
+impl<'a> FromIterator<Result<LogLine<'a>, (&'a str, JsonError)>> for ParsedLogs<'a> {
+    fn from_iter<T: IntoIterator<Item = Result<LogLine<'a>, (&'a str, JsonError)>>>(
         iter: T,
     ) -> Self {
         let iter = iter.into_iter();

src/main.rs

@@ -125,7 +125,7 @@ fn main() -> MainResult {
 
             progress.icr();
 
-            parsed.map_err(|err| (line_number, err))
+            parsed.map_err(|err| (line, err))
         })
         .progress_with_style(progress_style.clone())
         .collect();

src/ui/error_list.rs

@@ -1,22 +1,51 @@
 use crate::app::App;
 use crate::ui::style::TABLE_HEADER_STYLE;
-use crate::ui::table::ScrollbarTable;
-use ratatui::layout::Constraint;
+use crate::ui::table::{ScrollbarTable, ScrollbarTableState};
+use ratatui::buffer::Buffer;
+use ratatui::layout::{Constraint, Rect};
 use ratatui::text::Text;
-use ratatui::widgets::{Cell, Row};
+use ratatui::widgets::{Cell, Row, StatefulWidget};
 
-pub fn error_list<'a>(app: &App<'a>) -> ScrollbarTable<'a> {
-    let header = [Text::from("Error"), Text::from("Line")]
-        .into_iter()
-        .map(Cell::from)
-        .collect::<Row>()
-        .style(TABLE_HEADER_STYLE)
-        .height(1);
-
-    let widths = [Constraint::Percentage(50), Constraint::Percentage(50)];
-    ScrollbarTable::new(app.error_lines().map(error_row), widths).header(header)
+pub fn error_list<'a>(app: &'a App<'a>) -> ErrorList<'a> {
+    ErrorList {
+        errors: app.error_lines(),
+    }
 }
 
-fn error_row<'a>((line, err): (&'a str, &'a serde_json::Error)) -> Row<'a> {
+pub struct ErrorList<'a> {
+    errors: &'a [(&'a str, serde_json::Error)],
+}
+
+impl StatefulWidget for ErrorList<'_> {
+    type State = ScrollbarTableState;
+
+    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State)
+    where
+        Self: Sized,
+    {
+        let header = [Text::from("Error"), Text::from("Line")]
+            .into_iter()
+            .map(Cell::from)
+            .collect::<Row>()
+            .style(TABLE_HEADER_STYLE)
+            .height(1);
+
+        let widths = [Constraint::Percentage(50), Constraint::Percentage(50)];
+        let table = ScrollbarTable::new(
+            self.errors.iter().enumerate().map(|(i, (line, error))| {
+                if i.abs_diff(state.selected()) < 100 {
+                    error_row(line, error)
+                } else {
+                    Row::new::<[Text; 0]>([])
+                }
+            }),
+            widths,
+        )
+        .header(header);
+        table.render(area, buf, state);
+    }
+}
+
+fn error_row<'a>(line: &'a str, err: &'a serde_json::Error) -> Row<'a> {
     Row::new([Text::from(format!("{err}")), Text::from(line)])
 }

src/ui/state.rs

@@ -638,8 +638,8 @@ impl<'a> UiState<'a> {
             (UiState::Errors(state), UiEvent::Copy) => {
                 let raw = app
                     .error_lines()
-                    .nth(state.table_state.selected())
-                    .map(|(line, _)| line)
+                    .get(state.table_state.selected())
+                    .map(|(line, _)| *line)
                     .unwrap_or_default();
                 copy_osc(raw);
                 (false, UiState::Errors(state))