dofs: Skip empty pending lookups

Avoid resolving parent paths on read and metadata operations when the database has no pending create buffers.

Author: aron-cf

packages/dofs/src/fs/pendingWriteBuffer.ts

@@ -4,10 +4,13 @@ import { resolveInode } from "./resolve.js";
 import {
   getPendingWriteBufferByParent,
   getPendingWriteBufferByPath,
+  hasPendingWriteBuffers,
   type WriteBufferEntry,
 } from "./writeBuffer.js";
 
 export function findPendingWriteBuffer(db: Database, path: string): WriteBufferEntry | undefined {
+  if (!hasPendingWriteBuffers(db)) return undefined;
+
   const { parts, path: canonical } = canonicalizePath(path);
   const direct = getPendingWriteBufferByPath(db, canonical);
   if (direct !== undefined || parts.length === 0) return direct;

packages/dofs/src/fs/writeBuffer.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it } from "vitest";
 
 import type { Database } from "../storage.js";
 import { mkdir } from "./mkdir.js";
+import { findPendingWriteBuffer } from "./pendingWriteBuffer.js";
 import { readRangeSync } from "./readFile.js";
 import { resolveInode } from "./resolve.js";
 import { stat } from "./stat.js";
@@ -150,6 +151,20 @@ describe("buffered write lifecycle", () => {
 });
 
 describe("deferred-create lifecycle", () => {
+  it("skips parent resolution when no pending buffers exist", async () => {
+    await withDB((db) => {
+      const originalAll = db.all.bind(db);
+      let queries = 0;
+      db.all = ((query: string, ...bindings: unknown[]) => {
+        queries += 1;
+        return originalAll(query, ...bindings);
+      }) as typeof db.all;
+
+      expect(findPendingWriteBuffer(db, "/missing/file.txt")).toBeUndefined();
+      expect(queries).toBe(0);
+    });
+  });
+
   it("holds the file in memory until release commits one transaction", async () => {
     await withDB(async (db) => {
       openWriteBufferForCreateSync(db, "/pending.txt", { mode: 0o600 }, () => 1000);

packages/dofs/src/fs/writeBuffer.ts

@@ -96,6 +96,10 @@ export function getPendingWriteBufferByParent(
   return caches.get(db)?.byPendingParent.get(pendingParentKey(parentInode, leafName));
 }
 
+export function hasPendingWriteBuffers(db: Database): boolean {
+  return (caches.get(db)?.byPendingParent.size ?? 0) > 0;
+}
+
 // List pending-create buffers whose parent dirent matches `parentInode`.
 // Used by readdir so freshly-created-but-not-yet-released files show
 // up in directory listings between open and release.