feat: Enhance autocomplete cache with async initialization and improved eviction logic

[Ayyanaruto]

Based on discussion #8315 Implement asynchronous initialization for the autocomplete cache and refine eviction logic to optimize performance and memory usage. This update ensures a more efficient handling of cached entries with SQLite persistence.

---

Summary by cubic

Initialize the autocomplete cache asynchronously and move lookups to an in-memory LRU with periodic SQLite persistence. This improves startup, speeds up cache hits, and tightens eviction for better memory usage.

• New Features
  • Async singleton cache initialization that loads existing entries and starts a 30s flush timer.
  • In-memory longest-prefix matching with validation; timestamps updated on access.
  • LRU eviction in memory when capacity is exceeded, marking evicted keys for deletion.
  • Periodic flush persists dirty entries in a single transaction (upsert/delete) under a mutex, with graceful error handling.
  • CompletionProvider now awaits the cache on demand and disposes it cleanly via close().
  • Added comprehensive tests for cache operations, eviction, persistence, timer behavior, and resource cleanup.

[cubic-dev-ai]

3 issues found across 3 files

Prompt for AI agents (all 3 issues)

Understand the root cause of the following 3 issues and fix them.


<file name="core/autocomplete/util/AutocompleteLruCache.ts">

<violation number="1" location="core/autocomplete/util/AutocompleteLruCache.ts:218">
After close(), we need to clear the singleton so future get() calls reinitialize a fresh cache; otherwise callers receive an instance whose DB connection is already closed and whose flush timer never restarts.</violation>
</file>

<file name="core/autocomplete/util/AutocompleteLruCache.test.ts">

<violation number="1" location="core/autocomplete/util/AutocompleteLruCache.test.ts:4">
Mocking `async-mutex` removes the real Mutex implementation, so `cache.put` fails when it tries to call `this.mutex.acquire()`.</violation>

<violation number="2" location="core/autocomplete/util/AutocompleteLruCache.test.ts:638">
`jest.doMock(&quot;sqlite&quot;, …)` runs after AutocompleteLruCache imported `open`, leaving `open` as the default auto-mock and causing `AutocompleteLruCache.get()` to crash with an undefined database handle.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

After close(), we need to clear the singleton so future get() calls reinitialize a fresh cache; otherwise callers receive an instance whose DB connection is already closed and whose flush timer never restarts.

Prompt for AI agents

Address the following comment on core/autocomplete/util/AutocompleteLruCache.ts at line 218:

<comment>After close(), we need to clear the singleton so future get() calls reinitialize a fresh cache; otherwise callers receive an instance whose DB connection is already closed and whose flush timer never restarts.</comment>

<file context>
@@ -1,121 +1,227 @@
+   * Gracefully shuts down the cache.
+   * Stops the flush timer, persists pending changes, and closes database connection.
+   */
+  async close() {
+    if (this.flushTimer) {
+      clearInterval(this.flushTimer);
</file context>

✅ Addressed in 52ebf5d

[cubic-dev-ai]

jest.doMock("sqlite", …) runs after AutocompleteLruCache imported open, leaving open as the default auto-mock and causing AutocompleteLruCache.get() to crash with an undefined database handle.

Prompt for AI agents

Address the following comment on core/autocomplete/util/AutocompleteLruCache.test.ts at line 638:

<comment>`jest.doMock(&quot;sqlite&quot;, …)` runs after AutocompleteLruCache imported `open`, leaving `open` as the default auto-mock and causing `AutocompleteLruCache.get()` to crash with an undefined database handle.</comment>

<file context>
@@ -0,0 +1,646 @@
+
+    it(&quot;should return same instance on multiple calls&quot;, async () =&gt; {
+      const mockOpen = jest.fn().mockResolvedValue(mockDb);
+      jest.doMock(&quot;sqlite&quot;, () =&gt; ({ open: mockOpen }));
+
+      const instance1 = await AutocompleteLruCache.get();
</file context>

[Ayyanaruto]

Seems to be working to me correctly

[cubic-dev-ai]

Mocking async-mutex removes the real Mutex implementation, so cache.put fails when it tries to call this.mutex.acquire().

Prompt for AI agents

Address the following comment on core/autocomplete/util/AutocompleteLruCache.test.ts at line 4:

<comment>Mocking `async-mutex` removes the real Mutex implementation, so `cache.put` fails when it tries to call `this.mutex.acquire()`.</comment>

<file context>
@@ -0,0 +1,646 @@
+import AutocompleteLruCache from &quot;./AutocompleteLruCache&quot;;
+
+// Mock the external dependencies before importing
+jest.mock(&quot;async-mutex&quot;);
+jest.mock(&quot;sqlite&quot;);
+jest.mock(&quot;sqlite3&quot;);
</file context>

✅ Addressed in 52ebf5d

[cubic-dev-ai]

No issues found across 2 files