perf(server): mtime-gate the scheduler tick and memoize project-config reads (#200)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
2026-08-05 00:09:15 +08:00
parent c8894566e4
commit fc7cb5b8ed
11 changed files with 596 additions and 85 deletions
@@ -0,0 +1,106 @@
+/**
+ * ProjectConfigService read-cache semantics: repeat reads are served from the
+ * mtime-keyed parsed-table cache (one initial readFile), the service's own writes
+ * invalidate synchronously, an external edit is caught by the stat, a fresh mtime is
+ * never cached as clean (same-second-granularity guard), and the typed loadConfig
+ * view mirrors core's loadProjectConfig (missing file → the preset default config).
+ */
+import fs from "node:fs/promises";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import {
+  defaultProjectConfig,
+  projectConfigPath,
+  renderProjectConfigToml,
+} from "@prismshadow/penguin-core";
+import { ProjectConfigService } from "../src/services/project-config-service.js";
+import { makeTempRoot } from "./helpers.js";
+
+const P = "project-cfg";
+const PRICED = {
+  provider: "custom",
+  model_id: "m1",
+  pricing: { unit: "usd_per_mtok", cache_read: 1, cache_write: 2, output: 3 },
+};
+
+/** Ages the config's mtime past the gate's FRESH_MS window (fixed instants keep backdates idempotent). */
+async function backdate(file: string, instant: string): Promise<void> {
+  const at = new Date(instant);
+  await fs.utimes(file, at, at);
+}
+
+describe("project-config read cache", () => {
+  let root: string;
+  let svc: ProjectConfigService;
+  let file: string;
+
+  beforeEach(async () => {
+    root = await makeTempRoot();
+    svc = new ProjectConfigService(root);
+    file = projectConfigPath(root, P);
+    await svc.writeRaw(P, { name: "cached", models: [PRICED] });
+    await backdate(file, "2026-01-01T00:00:00Z");
+  });
+  afterEach(async () => {
+    vi.restoreAllMocks();
+    await fs.rm(root, { recursive: true, force: true });
+  });
+
+  it("repeat reads cost one readFile: pricing, name and the typed loadConfig view share the cached parse", async () => {
+    const reads = vi.spyOn(fs, "readFile");
+    expect(await svc.getPricing(P, "custom", "m1")).toEqual({
+      cacheRead: 1,
+      cacheWrite: 2,
+      output: 3,
+    });
+    expect(await svc.getPricing(P, "custom", "m1")).toEqual({
+      cacheRead: 1,
+      cacheWrite: 2,
+      output: 3,
+    });
+    expect(await svc.getName(P)).toBe("cached");
+    expect((await svc.loadConfig(P)).models.map((m) => m.model_id)).toEqual(["m1"]);
+    expect(reads).toHaveBeenCalledTimes(1);
+  });
+
+  it("a service write invalidates synchronously; once quiet, the next read re-parses exactly once", async () => {
+    await svc.getName(P); // Warm the cache at the stable mtime.
+    await svc.setName(P, "renamed");
+    await backdate(file, "2026-01-01T00:01:00Z");
+    const reads = vi.spyOn(fs, "readFile");
+    expect(await svc.getName(P)).toBe("renamed");
+    expect(await svc.getPricing(P, "custom", "m1")).toEqual({
+      cacheRead: 1,
+      cacheWrite: 2,
+      output: 3,
+    });
+    expect(reads).toHaveBeenCalledTimes(1);
+  });
+
+  it("an external edit (bypassing the service) is caught by the stat: new mtime → re-read", async () => {
+    expect(await svc.getName(P)).toBe("cached"); // Warm at the old mtime.
+    await fs.writeFile(
+      file,
+      renderProjectConfigToml({ name: "edited", models: [{ provider: "custom", model_id: "m2" }] }),
+      "utf8",
+    );
+    await backdate(file, "2026-01-01T00:02:00Z"); // Stable, but a different mtime than cached.
+    expect(await svc.getName(P)).toBe("edited");
+    expect((await svc.loadConfig(P)).models.map((m) => m.model_id)).toEqual(["m2"]);
+    expect(await svc.getPricing(P, "custom", "m1")).toBeUndefined();
+  });
+
+  it("a fresh mtime is never cached as clean: reads keep hitting disk until the file has been quiet", async () => {
+    await svc.setName(P, "fresh"); // mtime = now, inside the FRESH_MS window.
+    const reads = vi.spyOn(fs, "readFile");
+    await svc.getName(P);
+    await svc.getName(P);
+    expect(reads).toHaveBeenCalledTimes(2);
+  });
+
+  it("missing file: readRaw → {} and loadConfig → the preset default config (core loadProjectConfig parity)", async () => {
+    await svc.getName(P); // Warm, then delete out from under the cache.
+    await fs.rm(file);
+    expect(await svc.readRaw(P)).toEqual({});
+    expect(await svc.loadConfig(P)).toEqual(defaultProjectConfig());
+  });
+});