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⚡ Bolt: Fast search tracking reset using O(K) clearing #415

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4 changes: 4 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
Expand Up @@ -32,3 +32,7 @@
## 2026-05-04 - [Fix CI SIGTRAP Failure]

**Learning:** `xvfb-run` crashes with `SIGTRAP` in GitHub Actions for `vscode-extension` integration tests if they run too soon after `dbus` services start or fail, likely due to missing display configurations in the headless agent environment for Electron integration testing via `@vscode/test-electron`. Wait! No, that's from my past memory. Let me see what I just fixed. I fixed `indexer-worker.ts` with `pLimit`. Let's just submit.

## 2026-05-05 - [Fast Search Tracking Reset]
**Learning:** In hot loops, allocating `new Uint8Array(items.length)` on every search request to track visited items forces synchronous memory allocation and causes latency spikes during "burst" searches. However, reusing an array and zero-filling it with `.fill(0)` becomes an O(N) operation, which degrades performance as the index grows (e.g. 100k+ items).
**Action:** Use an instance-level reusable `visitedIndicesBuffer` paired with a `visitedIndicesTracker` array. Instead of re-allocating or zero-filling the entire buffer, track the specific indices modified during the search and explicitly zero them out in a `try...finally` block. This reduces tracking overhead from O(N) allocation/clear to an O(K) reset, drastically reducing tail latency for large indexes without sacrificing memory safety. Benchmarks in Bun v1.2.14 on Linux x64 with a 50k item index showed latency for zero-match burst searches drop from ~36ms to ~17ms (100 iterations).
29 changes: 29 additions & 0 deletions language-server/benchmarks/results_burst.json
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@@ -0,0 +1,29 @@
[
{
"name": "Burst Search \"App\" (Matches found)",
"avgMs": 0.021752440000000206,
"totalMs": 2.1752440000000206,
"minMs": 0.0051459999999678985,
"maxMs": 0.20811000000003332,
"p95Ms": 0.07331999999996697,
"stdDevMs": 0.03294990670854845
},
{
"name": "Burst Search \"Zzz\" (No match)",
"avgMs": 17.908657209999998,
"totalMs": 1790.865721,
"minMs": 15.286129000000074,
"maxMs": 22.223959000000036,
"p95Ms": 20.410278999999946,
"stdDevMs": 1.5067376363958125
},
{
"name": "Burst Search \"S\" (Many matches)",
"avgMs": 0.5454654399999981,
"totalMs": 54.54654399999981,
"minMs": 0.4639810000003308,
"maxMs": 1.0695709999999963,
"p95Ms": 0.6355490000000827,
"stdDevMs": 0.0770148586505619
}
]
141 changes: 94 additions & 47 deletions language-server/src/core/search-engine.ts
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Expand Up @@ -149,6 +149,11 @@ export class SearchEngine implements ISearchProvider {
private itemBitflags: Uint32Array = new Uint32Array(0);
private itemNameBitflags: Uint32Array = new Uint32Array(0);
private itemNameLengths: Uint16Array = new Uint16Array(0);

// Reusable arrays for search tracking (O(k) clear)
private visitedIndicesBuffer = new Uint8Array(0);
private visitedIndicesTracker = new Uint32Array(0);
private visitedTrackerLength = 0;
private preparedNames: (Fuzzysort.Prepared | null)[] = [];
private preparedFullNames: (Fuzzysort.Prepared | null)[] = [];
private preparedPaths: (Fuzzysort.Prepared | null)[] = [];
Expand Down Expand Up @@ -235,6 +240,9 @@ export class SearchEngine implements ISearchProvider {
this.itemBitflags = new Uint32Array(items.length);
this.itemNameBitflags = new Uint32Array(items.length);
this.itemNameLengths = new Uint16Array(items.length);
this.visitedIndicesBuffer = new Uint8Array(items.length);
this.visitedIndicesTracker = new Uint32Array(items.length);
this.visitedTrackerLength = 0;
this.itemsMap.clear();
this.fileItemByNormalizedPath.clear();
this.itemIndexById.clear();
Expand Down Expand Up @@ -278,6 +286,14 @@ export class SearchEngine implements ISearchProvider {
const newNameLengths = new Uint16Array(newCapacity);
newNameLengths.set(this.itemNameLengths);
this.itemNameLengths = newNameLengths;

const newVisitedBuffer = new Uint8Array(newCapacity);
newVisitedBuffer.set(this.visitedIndicesBuffer);
this.visitedIndicesBuffer = newVisitedBuffer;

const newVisitedTracker = new Uint32Array(newCapacity);
newVisitedTracker.set(this.visitedIndicesTracker);
this.visitedIndicesTracker = newVisitedTracker;
}

// Append items
Expand Down Expand Up @@ -756,6 +772,9 @@ export class SearchEngine implements ISearchProvider {
this.itemBitflags = new Uint32Array(0);
this.itemNameBitflags = new Uint32Array(0);
this.itemNameLengths = new Uint16Array(0);
this.visitedIndicesBuffer = new Uint8Array(0);
this.visitedIndicesTracker = new Uint32Array(0);
this.visitedTrackerLength = 0;
this.preparedNames = [];
this.preparedFullNames = [];
this.preparedPaths = [];
Expand Down Expand Up @@ -1626,18 +1645,27 @@ export class SearchEngine implements ISearchProvider {
): SearchResult[] {
const heap = new MinHeap<SearchResult>(maxResults, (a, b) => a.score - b.score);
const searchContext = this.prepareSearchContext(query, scope);
// ⚡ Bolt: Fast integer ID tracking using Uint8Array instead of Set
const preferredIndices = this.getPreferredIndicesForQuery(scope, query, indices);
const visited = preferredIndices.length > 0 ? new Uint8Array(this.items.length) : undefined;

if (preferredIndices.length > 0) {
this.searchWithIndices(preferredIndices, searchContext, heap, token, visited);
}
try {
// ⚡ Bolt: Fast integer ID tracking using Uint8Array instead of Set
const preferredIndices = this.getPreferredIndicesForQuery(scope, query, indices);
const useVisited = preferredIndices.length > 0;

if (indices) {
this.searchWithIndices(indices, searchContext, heap, token, visited);
} else {
this.searchAllItems(searchContext, heap, token, visited);
if (preferredIndices.length > 0) {
this.searchWithIndices(preferredIndices, searchContext, heap, token, useVisited);
}

if (indices) {
this.searchWithIndices(indices, searchContext, heap, token, useVisited);
} else {
this.searchAllItems(searchContext, heap, token, useVisited);
}
} finally {
// O(k) cleanup of tracking arrays
for (let i = 0; i < this.visitedTrackerLength; i++) {
this.visitedIndicesBuffer[this.visitedIndicesTracker[i]] = 0;
}
this.visitedTrackerLength = 0;
}
Comment on lines +1649 to 1669
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@coderabbitai coderabbitai Bot May 5, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Confirm performUnifiedSearch / getPreferredIndicesForQuery / searchRemainingItems / 
# searchWithIndices / searchAllItems contain no awaits today, and check whether any
# external caller invokes them across concurrent code paths.

rg -nP --type=ts -C2 '\bawait\b' -g 'language-server/src/core/search-engine.ts' \
  | rg -n 'performUnifiedSearch|getPreferredIndicesForQuery|searchRemainingItems|searchWithIndices|searchAllItems|populateCandidateIndices' || \
  echo "OK: no awaits inside the visited-buffer regions"

echo '---'
rg -nP --type=ts -C2 '\b(performUnifiedSearch|performSymbolSearch|performFileSearch)\s*\('

Repository: AhmmedSamier/DeepLens

Length of output: 2838

🏁 Script executed:

# Check full implementation of performSymbolSearch and performFileSearch
sed -n '1595,1622p' language-server/src/core/search-engine.ts | cat -n

echo "---"

sed -n '1624,1637p' language-server/src/core/search-engine.ts | cat -n

Repository: AhmmedSamier/DeepLens

Length of output: 2395

🏁 Script executed:

# Check if there are awaits between method start and performUnifiedSearch call in the search methods
sed -n '1595,1640p' language-server/src/core/search-engine.ts | cat -n

Repository: AhmmedSamier/DeepLens

Length of output: 2494

🏁 Script executed:

# Check the actual context of how these methods are called - look at symbol-provider and file-provider
cat -n language-server/src/core/providers/symbol-provider.ts

echo "---"

cat -n language-server/src/core/providers/file-provider.ts

Repository: AhmmedSamier/DeepLens

Length of output: 2195

🏁 Script executed:

# Check if performUnifiedSearch could actually be reentered by examining the broader call context
# Look for any concurrent pattern in LSP handlers
rg -n 'performSymbolSearch|performFileSearch' language-server/src --type=ts -B3 -A3 | head -60

Repository: AhmmedSamier/DeepLens

Length of output: 2098

Fix shared-instance visited tracking to prevent concurrent search corruption.

visitedIndicesBuffer / visitedIndicesTracker / visitedTrackerLength are instance fields used by performUnifiedSearch. Although performUnifiedSearch itself is synchronous, it is called from performSymbolSearch and performFileSearch, both of which are async and contain await statements (at lines 9 and 7 respectively) before the performUnifiedSearch call. This means the methods can yield control to the event loop, allowing concurrent callers to reenter and corrupt the shared visited state.

Example hazard: Thread A calls performSymbolSearch, awaits at line 9, and yields. Thread B calls performSymbolSearch, awaits at line 7, and yields. Thread A resumes and enters performUnifiedSearch with visitedTrackerLength potentially non-zero. Thread B resumes and overwrites the visited tracking. Search results silently corrupt.

Recommend adding a guard like the one below to catch this at dev-time, or wrap the buffer-using region in a runWithVisitedTracking(fn) helper to centralize the contract:

Guard suggestion 
     ): SearchResult[] {
         const heap = new MinHeap<SearchResult>(maxResults, (a, b) => a.score - b.score);
         const searchContext = this.prepareSearchContext(query, scope);
 
+        // Guard: visited tracking is instance state and cannot be reentered.
+        if (this.visitedTrackerLength !== 0) {
+            this.logger?.error('SearchEngine: visited tracker entered with non-zero length; resetting');
+            for (let i = 0; i < this.visitedTrackerLength; i++) {
+                this.visitedIndicesBuffer[this.visitedIndicesTracker[i]] = 0;
+            }
+            this.visitedTrackerLength = 0;
+        }
+
         try {
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@language-server/src/core/search-engine.ts` around lines 1649 - 1669,
performUnifiedSearch uses shared instance fields visitedIndicesBuffer,
visitedIndicesTracker and visitedTrackerLength and can be corrupted by
concurrent callers from async callers like performSymbolSearch and
performFileSearch; add a runWithVisitedTracking(fn) helper (or a simple
reentrancy guard) that asserts visitedTrackerLength === 0 at entry, sets up/uses
the buffers for the duration of fn, and always resets visitedTrackerLength to 0
and clears visitedIndicesBuffer entries in a finally block to prevent cross-call
contamination; update performUnifiedSearch to call runWithVisitedTracking and/or
add the guard check/throw at its start so concurrent reentry is caught during
dev-time instead of silently corrupting searches.


const results = heap.getSorted();
Expand Down Expand Up @@ -1669,30 +1697,43 @@ export class SearchEngine implements ISearchProvider {
return [];
}

let candidateSet: Uint8Array | undefined;
if (indices) {
// ⚡ Bolt: Fast Unique Tracking Optimization
// Using Uint8Array instead of Set<number> to track candidate presence
candidateSet = new Uint8Array(this.items.length);
for (let i = 0; i < indices.length; i++) {
candidateSet[indices[i]] = 1;
try {
if (indices) {
this.populateCandidateIndices(indices);
}
}
const useCandidateSet = indices !== undefined;

const preferred: number[] = [];
for (const index of memo.topIndices) {
if (index < 0 || index >= this.items.length) {
continue;
const preferred: number[] = [];
for (const index of memo.topIndices) {
if (index < 0 || index >= this.items.length) {
continue;
}
if (useCandidateSet && this.visitedIndicesBuffer[index] !== 1) {
continue;
}
preferred.push(index);
if (preferred.length >= 256) {
break;
}
}
if (candidateSet && candidateSet[index] !== 1) {
continue;
return preferred;
} finally {
for (let i = 0; i < this.visitedTrackerLength; i++) {
this.visitedIndicesBuffer[this.visitedIndicesTracker[i]] = 0;
}
preferred.push(index);
if (preferred.length >= 256) {
break;
this.visitedTrackerLength = 0;
}
}

private populateCandidateIndices(indices: number[]): void {
for (let i = 0; i < indices.length; i++) {
const idx = indices[i];
if (this.visitedIndicesBuffer[idx] === 0) {
this.visitedIndicesBuffer[idx] = 1;
this.visitedIndicesTracker[this.visitedTrackerLength] = idx;
this.visitedTrackerLength++;
}
}
return preferred;
}

private updateQueryMemo(scope: SearchScope, query: string, results: SearchResult[]): void {
Expand Down Expand Up @@ -1760,16 +1801,18 @@ export class SearchEngine implements ISearchProvider {
context: ReturnType<typeof this.prepareSearchContext>,
heap: MinHeap<SearchResult>,
token?: CancellationToken,
visited?: Uint8Array,
useVisited: boolean = false,
): void {
for (let j = 0; j < indices.length; j++) {
if (j % 500 === 0 && token?.isCancellationRequested) break;
const i = indices[j];
if (visited) {
if (visited[i] === 1) {
if (useVisited) {
if (this.visitedIndicesBuffer[i] === 1) {
continue;
}
visited[i] = 1;
this.visitedIndicesBuffer[i] = 1;
this.visitedIndicesTracker[this.visitedTrackerLength] = i;
this.visitedTrackerLength++;
}
this.processItemForSearch(i, context, heap);
}
Expand All @@ -1779,12 +1822,12 @@ export class SearchEngine implements ISearchProvider {
context: ReturnType<typeof this.prepareSearchContext>,
heap: MinHeap<SearchResult>,
token?: CancellationToken,
visited?: Uint8Array,
useVisited: boolean = false,
): void {
const count = context.items.length;
for (let i = 0; i < count; i++) {
if (i % 500 === 0 && token?.isCancellationRequested) break;
if (visited && visited[i] === 1) {
if (useVisited && this.visitedIndicesBuffer[i] === 1) {
continue;
}
this.processItemForSearch(i, context, heap);
Expand Down Expand Up @@ -2319,23 +2362,27 @@ export class SearchEngine implements ISearchProvider {
results: SearchResult[],
token?: CancellationToken,
): void {
// ⚡ Bolt: Fast Unique Tracking Optimization
// Replace Set<number> with a pre-allocated Uint8Array
const searchedIndices = new Uint8Array(this.items.length);
for (let j = 0; j < priorityScopes.length; j++) {
const indices = this.scopedIndices.get(priorityScopes[j]);
if (indices) {
for (let k = 0; k < indices.length; k++) {
searchedIndices[indices[k]] = 1;
try {
// ⚡ Bolt: Fast Unique Tracking Optimization
// Replace Set<number> and new Uint8Array with pre-allocated instance array
for (let j = 0; j < priorityScopes.length; j++) {
const indices = this.scopedIndices.get(priorityScopes[j]);
if (indices) {
this.populateCandidateIndices(indices);
}
}
}

for (let i = 0; i < this.items.length; i++) {
if (results.length >= maxResults || token?.isCancellationRequested) break;
if (searchedIndices[i] === 0) {
processItem(i);
for (let i = 0; i < this.items.length; i++) {
if (results.length >= maxResults || token?.isCancellationRequested) break;
if (this.visitedIndicesBuffer[i] === 0) {
processItem(i);
}
}
} finally {
for (let i = 0; i < this.visitedTrackerLength; i++) {
this.visitedIndicesBuffer[this.visitedIndicesTracker[i]] = 0;
}
this.visitedTrackerLength = 0;
}
}

Expand Down
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