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fix(buffer): avoid shared _extendedAttrs sentinel breaking addon-image

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EMPTY_SPARSE_EXTENDED was shared across lines via copyFrom; addon-image
writes _extendedAttrs directly without copy-on-write, which caused tile
eviction failures and broke instanceof Object checks.

Use undefined for empty extended maps (keep EMPTY_SPARSE_MAP for _combined).
Ensure addon-image forks the map before writes and update the accessor test.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>
This commit is contained in:
Cursor Agent
2026-06-06 21:51:23 +00:00
co-authored by Daniel Imms
parent 81b3b1ec46
commit dec5452fc0
4 changed files with 38 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/common/buffer/BufferLine.ts
+23 -27
View File
@@ -72,20 +72,19 @@ export interface IBufferLineStringCache {
* memory allocs / GC pressure can be greatly reduced by reusing the CellData object.
*/
/**
* Shared empty sparse maps for lines with no combining/extended data.
* Uses a sentinel + copy-on-write (not `undefined`) so `copyFrom` can detect empty maps
* with reference equality. `undefined` was explored but regressed sparse `copyFrom`;
* `Object.freeze` on these sentinels is safe with COW but did not improve perf.
* Shared empty sparse map for lines with no combining data.
* Uses a sentinel + copy-on-write so `copyFrom` can detect empty `_combined` with
* reference equality. `_extendedAttrs` uses `undefined` instead (addon-image writes
* the map directly without BufferLine APIs).
*/
const EMPTY_SPARSE_MAP: {[index: number]: string} = Object.create(null);
const EMPTY_SPARSE_EXTENDED: {[index: number]: IExtendedAttrs | undefined} = Object.create(null);
export class BufferLine implements IBufferLine {
protected _data: Uint32Array;
/** Sparse cache; only read when `IS_COMBINED_MASK` is set in `_data`. */
protected _combined: {[index: number]: string} = EMPTY_SPARSE_MAP;
/** Sparse cache; only read when `HAS_EXTENDED` is set in `_data`. */
protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} = EMPTY_SPARSE_EXTENDED;
protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} | undefined;
protected _stringCacheEntryRef: WeakRef<IBufferLineStringCacheEntry> | undefined;
public length: number;
@@ -221,7 +220,7 @@ export class BufferLine implements IBufferLine {
cell.combinedData = '';
}
if (cell.bg & BgFlags.HAS_EXTENDED) {
cell.extended = this._extendedAttrs[index]!;
cell.extended = this._extendedAttrs![index]!;
} else {
// Do not mutate cell.extended in place: it may still reference this line's map entry from a
// prior loadCell into a reused CellData (e.g. $workCell during insert/delete).
@@ -240,8 +239,7 @@ export class BufferLine implements IBufferLine {
this._combined[index] = cell.combinedData;
}
if (cell.bg & BgFlags.HAS_EXTENDED) {
this._ensureExtendedAttrsMap();
this._extendedAttrs[index] = cell.extended;
this._ensureExtendedAttrsMap()[index] = cell.extended;
}
this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = cell.content;
this._data[index * Constants.CELL_INDICIES + Cell.FG] = cell.fg;
@@ -256,8 +254,7 @@ export class BufferLine implements IBufferLine {
public setCellFromCodepoint(index: number, codePoint: number, width: number, attrs: IAttributeData): void {
this._invalidateStringCache();
if (attrs.bg & BgFlags.HAS_EXTENDED) {
this._ensureExtendedAttrsMap();
this._extendedAttrs[index] = attrs.extended;
this._ensureExtendedAttrsMap()[index] = attrs.extended;
}
this._data[index * Constants.CELL_INDICIES + Cell.CONTENT] = codePoint | (width << Content.WIDTH_SHIFT);
this._data[index * Constants.CELL_INDICIES + Cell.FG] = attrs.fg;
@@ -425,11 +422,13 @@ export class BufferLine implements IBufferLine {
}
}
// remove any cut off extended attributes
const extKeys = Object.keys(this._extendedAttrs);
for (let i = 0; i < extKeys.length; i++) {
const key = parseInt(extKeys[i], 10);
if (key >= cols) {
delete this._extendedAttrs[key];
if (this._extendedAttrs) {
const extKeys = Object.keys(this._extendedAttrs);
for (let i = 0; i < extKeys.length; i++) {
const key = parseInt(extKeys[i], 10);
if (key >= cols) {
delete this._extendedAttrs[key];
}
}
}
}
@@ -466,7 +465,7 @@ export class BufferLine implements IBufferLine {
return;
}
this._combined = EMPTY_SPARSE_MAP;
this._extendedAttrs = EMPTY_SPARSE_EXTENDED;
this._extendedAttrs = undefined;
for (let i = 0; i < this.length; ++i) {
this.setCell(i, fillCellData);
}
@@ -627,8 +626,7 @@ export class BufferLine implements IBufferLine {
this._combined[destCol] = src._combined[srcCol];
}
if (src._data[srcStart + Cell.BG] & BgFlags.HAS_EXTENDED) {
this._ensureExtendedAttrsMap();
this._extendedAttrs[destCol] = src._extendedAttrs[srcCol];
this._ensureExtendedAttrsMap()[destCol] = src._extendedAttrs![srcCol]!;
}
}
@@ -637,10 +635,10 @@ export class BufferLine implements IBufferLine {
const srcCombined = line._combined;
const srcExtended = line._extendedAttrs;
// Fast path: blank / scroll-recycle source (shared empty sentinel or plain empty object).
if (srcCombined === EMPTY_SPARSE_MAP && srcExtended === EMPTY_SPARSE_EXTENDED) {
// Fast path: blank / scroll-recycle source (empty `_combined` sentinel, no extended map).
if (srcCombined === EMPTY_SPARSE_MAP && !srcExtended) {
this._combined = EMPTY_SPARSE_MAP;
this._extendedAttrs = EMPTY_SPARSE_EXTENDED;
this._extendedAttrs = undefined;
return;
}
this._copySparseMapsFromDense(line);
@@ -663,7 +661,7 @@ export class BufferLine implements IBufferLine {
combined[i] = srcCombined[i];
}
if (srcData[start + Cell.BG] & BgFlags.HAS_EXTENDED) {
extendedAttrs[i] = srcExtended[i];
extendedAttrs[i] = srcExtended![i];
}
}
}
@@ -674,9 +672,7 @@ export class BufferLine implements IBufferLine {
}
}
private _ensureExtendedAttrsMap(): void {
if (this._extendedAttrs === EMPTY_SPARSE_EXTENDED) {
this._extendedAttrs = {};
}
private _ensureExtendedAttrsMap(): {[index: number]: IExtendedAttrs | undefined} {
return this._extendedAttrs ??= {};
}
}