Files
zed/crates/editor/src/test.rs
T
Antonio Scandurra 6639b4ff65 Fix editor hang when positioned above viewport (#45077)
Fixes the hang introduced in #44995 (which was reverted in #45011) and
re-enables the optimization.

## Background

PR #44995 introduced an optimization to skip rendering lines that are
clipped by parent containers (e.g., when a large AutoHeight editor is
inside a scrollable List). This significantly improved performance for
large diffs in the Agent Panel.
However, #45011 reverted this change because it caused the main thread
to hang for 100+ seconds in certain scenarios, requiring a force quit to
recover.

## Root Cause
The original analysis in #45011 suggested that visible_bounds wasn’t
being intersected properly, but that was incorrect—the intersection via
with_content_mask works correctly. The actual bug: when an editor is
positioned above the visible viewport (e.g., scrolled past in a List),
the clipping calculation produces a start_row that exceeds max_row:

1. Editor’s bounds.origin.y becomes very negative (e.g., -10000px)
2. After intersection, visible_bounds.origin.y is at the viewport top
(e.g., 0)
3. clipped_top_in_lines = (0 - (-10000)) / line_height = huge number
4. start_row = huge number, but end_row is clamped to max_row
5. This creates an invalid range where start_row > end_row

This caused two different failures depending on build mode:
- Debug mode: Panic from subtraction overflow in
Range<DisplayRow>::len()
- Release mode: Integer wraparound causing blocks_in_range to enter an
infinite loop (the 100+ second hang)

## Fix

Simply clamp start_row to max_row, ensuring the row range is always
valid:

```rs
let start_row = cmp::min(
    DisplayRow((scroll_position.y + clipped_top_in_lines).floor() as u32),
    max_row,
);
```

## Testing
Added a regression test that draws an editor at y=-10000 to simulate an
editor that’s been scrolled past in a List. This would panic in debug
mode (and hang in release mode) before the fix.

Release Notes:
- Improved agent panel performance when rendering large diffs.
2025-12-17 09:17:45 +00:00

252 lines
8.2 KiB
Rust

pub mod editor_lsp_test_context;
pub mod editor_test_context;
use std::{rc::Rc, sync::LazyLock};
pub use crate::rust_analyzer_ext::expand_macro_recursively;
use crate::{
DisplayPoint, Editor, EditorMode, FoldPlaceholder, MultiBuffer, SelectionEffects,
display_map::{
Block, BlockPlacement, CustomBlockId, DisplayMap, DisplayRow, DisplaySnapshot,
ToDisplayPoint,
},
};
use collections::HashMap;
use gpui::{
AppContext as _, Context, Entity, EntityId, Font, FontFeatures, FontStyle, FontWeight, Pixels,
VisualTestContext, Window, font, size,
};
use multi_buffer::{MultiBufferOffset, ToPoint};
use pretty_assertions::assert_eq;
use project::{Project, project_settings::DiagnosticSeverity};
use ui::{App, BorrowAppContext, px};
use util::test::{generate_marked_text, marked_text_offsets, marked_text_ranges};
#[cfg(test)]
#[ctor::ctor]
fn init_logger() {
zlog::init_test();
}
pub fn test_font() -> Font {
static TEST_FONT: LazyLock<Font> = LazyLock::new(|| {
#[cfg(not(target_os = "windows"))]
{
font("Helvetica")
}
#[cfg(target_os = "windows")]
{
font("Courier New")
}
});
TEST_FONT.clone()
}
// Returns a snapshot from text containing '|' character markers with the markers removed, and DisplayPoints for each one.
#[track_caller]
pub fn marked_display_snapshot(
text: &str,
cx: &mut gpui::App,
) -> (DisplaySnapshot, Vec<DisplayPoint>) {
let (unmarked_text, markers) = marked_text_offsets(text);
let font = Font {
family: ".ZedMono".into(),
features: FontFeatures::default(),
fallbacks: None,
weight: FontWeight::default(),
style: FontStyle::default(),
};
let font_size: Pixels = 14usize.into();
let buffer = MultiBuffer::build_simple(&unmarked_text, cx);
let display_map = cx.new(|cx| {
DisplayMap::new(
buffer,
font,
font_size,
None,
1,
1,
FoldPlaceholder::test(),
DiagnosticSeverity::Warning,
cx,
)
});
let snapshot = display_map.update(cx, |map, cx| map.snapshot(cx));
let markers = markers
.into_iter()
.map(|offset| MultiBufferOffset(offset).to_display_point(&snapshot))
.collect();
(snapshot, markers)
}
#[track_caller]
pub fn select_ranges(
editor: &mut Editor,
marked_text: &str,
window: &mut Window,
cx: &mut Context<Editor>,
) {
let (unmarked_text, text_ranges) = marked_text_ranges(marked_text, true);
assert_eq!(editor.text(cx), unmarked_text);
editor.change_selections(SelectionEffects::no_scroll(), window, cx, |s| {
s.select_ranges(
text_ranges
.into_iter()
.map(|range| MultiBufferOffset(range.start)..MultiBufferOffset(range.end)),
)
});
}
#[track_caller]
pub fn assert_text_with_selections(
editor: &mut Editor,
marked_text: &str,
cx: &mut Context<Editor>,
) {
let (unmarked_text, _text_ranges) = marked_text_ranges(marked_text, true);
assert_eq!(editor.text(cx), unmarked_text, "text doesn't match");
let actual = generate_marked_text(
&editor.text(cx),
&editor
.selections
.ranges::<MultiBufferOffset>(&editor.display_snapshot(cx))
.into_iter()
.map(|range| range.start.0..range.end.0)
.collect::<Vec<_>>(),
marked_text.contains("«"),
);
assert_eq!(actual, marked_text, "Selections don't match");
}
// RA thinks this is dead code even though it is used in a whole lot of tests
#[allow(dead_code)]
#[cfg(any(test, feature = "test-support"))]
pub(crate) fn build_editor(
buffer: Entity<MultiBuffer>,
window: &mut Window,
cx: &mut Context<Editor>,
) -> Editor {
Editor::new(EditorMode::full(), buffer, None, window, cx)
}
pub(crate) fn build_editor_with_project(
project: Entity<Project>,
buffer: Entity<MultiBuffer>,
window: &mut Window,
cx: &mut Context<Editor>,
) -> Editor {
Editor::new(EditorMode::full(), buffer, Some(project), window, cx)
}
#[derive(Default)]
struct TestBlockContent(
HashMap<(EntityId, CustomBlockId), Rc<dyn Fn(&mut VisualTestContext) -> String>>,
);
impl gpui::Global for TestBlockContent {}
pub fn set_block_content_for_tests(
editor: &Entity<Editor>,
id: CustomBlockId,
cx: &mut App,
f: impl Fn(&mut VisualTestContext) -> String + 'static,
) {
cx.update_default_global::<TestBlockContent, _>(|bc, _| {
bc.0.insert((editor.entity_id(), id), Rc::new(f))
});
}
pub fn block_content_for_tests(
editor: &Entity<Editor>,
id: CustomBlockId,
cx: &mut VisualTestContext,
) -> Option<String> {
let f = cx.update(|_, cx| {
cx.default_global::<TestBlockContent>()
.0
.get(&(editor.entity_id(), id))
.cloned()
})?;
Some(f(cx))
}
pub fn editor_content_with_blocks(editor: &Entity<Editor>, cx: &mut VisualTestContext) -> String {
let draw_size = size(px(3000.0), px(3000.0));
cx.simulate_resize(draw_size);
cx.draw(gpui::Point::default(), draw_size, |_, _| editor.clone());
let (snapshot, mut lines, blocks) = editor.update_in(cx, |editor, window, cx| {
let snapshot = editor.snapshot(window, cx);
let text = editor.display_text(cx);
let lines = text.lines().map(|s| s.to_string()).collect::<Vec<String>>();
let blocks = snapshot
.blocks_in_range(DisplayRow(0)..snapshot.max_point().row())
.map(|(row, block)| (row, block.clone()))
.collect::<Vec<_>>();
(snapshot, lines, blocks)
});
for (row, block) in blocks {
match block {
Block::Custom(custom_block) => {
if let BlockPlacement::Near(x) = &custom_block.placement
&& snapshot.intersects_fold(x.to_point(&snapshot.buffer_snapshot()))
{
continue;
};
let content = block_content_for_tests(editor, custom_block.id, cx)
.expect("block content not found");
// 2: "related info 1 for diagnostic 0"
if let Some(height) = custom_block.height {
if height == 0 {
lines[row.0 as usize - 1].push_str(" § ");
lines[row.0 as usize - 1].push_str(&content);
} else {
let block_lines = content.lines().collect::<Vec<_>>();
assert_eq!(block_lines.len(), height as usize);
lines[row.0 as usize].push_str("§ ");
lines[row.0 as usize].push_str(block_lines[0].trim_end());
for i in 1..height as usize {
if row.0 as usize + i >= lines.len() {
lines.push("".to_string());
};
lines[row.0 as usize + i].push_str("§ ");
lines[row.0 as usize + i].push_str(block_lines[i].trim_end());
}
}
}
}
Block::FoldedBuffer {
first_excerpt,
height,
} => {
lines[row.0 as usize].push_str(&cx.update(|_, cx| {
format!("§ {}", first_excerpt.buffer.file().unwrap().file_name(cx))
}));
for row in row.0 + 1..row.0 + height {
lines[row as usize].push_str("§ -----");
}
}
Block::ExcerptBoundary { height, .. } => {
for row in row.0..row.0 + height {
lines[row as usize].push_str("§ -----");
}
}
Block::BufferHeader { excerpt, height } => {
lines[row.0 as usize].push_str(
&cx.update(|_, cx| {
format!("§ {}", excerpt.buffer.file().unwrap().file_name(cx))
}),
);
for row in row.0 + 1..row.0 + height {
lines[row as usize].push_str("§ -----");
}
}
}
}
lines.join("\n")
}