next/after support and better AsyncLocalStorage context in general

examples/app-router/app/api/after/revalidate/route.tsx

@@ -0,0 +1,16 @@
+import { revalidateTag } from "next/cache";
+import { NextResponse, unstable_after as after } from "next/server";
+
+export function POST() {
+  after(
+    () =>
+      new Promise<void>((resolve) =>
+        setTimeout(() => {
+          revalidateTag("date");
+          resolve();
+        }, 5000),
+      ),
+  );
+
+  return NextResponse.json({ success: true });
+}

examples/app-router/app/api/after/ssg/route.tsx

@@ -0,0 +1,13 @@
+import { unstable_cache } from "next/cache";
+import { NextResponse } from "next/server";
+
+export const dynamic = "force-static";
+
+export async function GET() {
+  const dateFn = unstable_cache(() => new Date().toISOString(), ["date"], {
+    tags: ["date"],
+  });
+  const date = await dateFn();
+  console.log("date", date);
+  return NextResponse.json({ date: date });
+}

examples/app-router/next.config.ts

@@ -17,6 +17,9 @@ const nextConfig: NextConfig = {
       },
     ],
   },
+  experimental: {
+    after: true,
+  },
   redirects: async () => {
     return [
       {

packages/tests-e2e/tests/appRouter/after.test.ts

@@ -0,0 +1,29 @@
+import { test, expect } from "@playwright/test";
+
+test("Next after", async ({ request }) => {
+  const initialSSG = await request.get("/api/after/ssg");
+  expect(initialSSG.status()).toEqual(200);
+  const initialSSGJson = await initialSSG.json();
+
+  // We then fire a post request that will revalidate the SSG page 5 seconds after, but should respond immediately
+  const dateNow = Date.now();
+  const revalidateSSG = await request.post("/api/after/revalidate");
+  expect(revalidateSSG.status()).toEqual(200);
+  const revalidateSSGJson = await revalidateSSG.json();
+  expect(revalidateSSGJson.success).toEqual(true);
+  // This request should take less than 5 seconds to respond
+  expect(Date.now() - dateNow).toBeLessThan(5000);
+
+  // We want to immediately check if the SSG page has been revalidated, it should not have been
+  const notRevalidatedSSG = await request.get("/api/after/ssg");
+  expect(notRevalidatedSSG.status()).toEqual(200);
+  const notRevalidatedSSGJson = await notRevalidatedSSG.json();
+  expect(notRevalidatedSSGJson.date).toEqual(initialSSGJson.date);
+
+  // We then wait for 5 seconds to ensure the SSG page has been revalidated
+  await new Promise((resolve) => setTimeout(resolve, 5000));
+  const revalidatedSSG = await request.get("/api/after/ssg");
+  expect(revalidatedSSG.status()).toEqual(200);
+  const revalidatedSSGJson = await revalidatedSSG.json();
+  expect(revalidatedSSGJson.date).not.toEqual(initialSSGJson.date);
+});