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⚡ Bolt: Avoid cloning large scrollback buffers during terminal init #389

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⚡ Bolt: Avoid cloning large scrollback buffers during terminal init #389

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
## 2024-08-04 - [Avoid Eager Cloning from Mutex]

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 4, 2026

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P1 Badge Remove the one-off .jules root bucket

This commit creates a new top-level directory solely for a task-specific automation note, rather than a durable category of project content. Keeping this artifact makes the repository structure less predictable and leaves an unowned document that can become stale; omit it instead of introducing .jules/.

AGENTS.md reference: AGENTS.md:L131-L131

Useful? React with 👍 / 👎.

**Learning:** Eagerly cloning large data structures (like a 64KB scrollback string) out of a `Mutex` just to pass to read-only functions causes significant unnecessary heap allocations during hot paths like terminal spawn.
**Action:** Keep the processing logic inside the lock's scope (using `.and_then` or `.is_some_and`) and borrow the value with `.as_deref()` to eliminate redundant heap allocations.
35 changes: 16 additions & 19 deletions crates/forktty-ui-gtk/src/gtk_app/controller/embedded_spawn.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -252,16 +252,17 @@ impl TerminalController {
&surface_id,
generation,
|| {
let stored = model.lock().ok().and_then(|model| {
model
let bytes = model.lock().ok().and_then(|model| {
let stored = model
.surface(&surface_id)
.and_then(|surface| surface.persisted_scrollback.clone())
.and_then(|surface| surface.persisted_scrollback.as_deref());
embedded_scrollback_restore_bytes(
persistent_scrollback_lines,
embedder.supports_restore_scrollback(),
stored,
)
});
if let Some(bytes) = embedded_scrollback_restore_bytes(
persistent_scrollback_lines,
embedder.supports_restore_scrollback(),
stored.as_deref(),
) {
if let Some(bytes) = bytes {
if let Err(err) =
unsafe { embedder.restore_scrollback(&widget, &bytes) }
{
Expand Down Expand Up @@ -483,21 +484,17 @@ impl TerminalController {
let model = self.model.clone();
let surface_id = request.surface_id.clone();
let weak_widget = widget.downgrade();
let mut skip_initial_snapshot = model
.lock()
.ok()
.and_then(|model| {
model
.surface(&surface_id)
.and_then(|surface| surface.persisted_scrollback.clone())
})
.as_deref()
.is_some_and(|persisted_scrollback| {
let mut skip_initial_snapshot = model.lock().ok().is_some_and(|model| {
let stored = model
.surface(&surface_id)
.and_then(|surface| surface.persisted_scrollback.as_deref());
stored.is_some_and(|persisted_scrollback| {
should_skip_initial_embedded_scrollback_snapshot(
embedder.supports_restore_scrollback(),
Some(persisted_scrollback),
)
});
})
});
let mut last_snapshot: Option<String> = None;
glib::timeout_add_local(EMBEDDED_GHOSTTY_SCROLLBACK_SNAPSHOT_INTERVAL, move || {
let Some(widget) = weak_widget.upgrade() else {
Expand Down
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