Set Next-Router-Stale-Time header from collected stale times

This is only done during prerender which is typically the only things we prefetch (other than loading.tsx).
sebmarkbage · Oct 14, 2024 · 6c52126 · 6c52126
1 parent f847dae
commit 6c52126
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diff --git a/packages/next/src/client/components/app-router-headers.ts b/packages/next/src/client/components/app-router-headers.ts
@@ -11,6 +11,7 @@ export const NEXT_ROUTER_PREFETCH_HEADER = 'Next-Router-Prefetch' as const
 // be merged into a single enum.
 export const NEXT_ROUTER_SEGMENT_PREFETCH_HEADER =
   'Next-Router-Segment-Prefetch' as const
+export const NEXT_ROUTER_STALE_TIME_HEADER = 'Next-Router-Stale-Time' as const
 export const NEXT_HMR_REFRESH_HEADER = 'Next-HMR-Refresh' as const
 export const NEXT_URL = 'Next-Url' as const
 export const RSC_CONTENT_TYPE_HEADER = 'text/x-component' as const

diff --git a/packages/next/src/server/app-render/app-render.tsx b/packages/next/src/server/app-render/app-render.tsx
@@ -43,6 +43,7 @@ import {
   NEXT_HMR_REFRESH_HEADER,
   NEXT_ROUTER_PREFETCH_HEADER,
   NEXT_ROUTER_STATE_TREE_HEADER,
+  NEXT_ROUTER_STALE_TIME_HEADER,
   NEXT_URL,
   RSC_HEADER,
 } from '../../client/components/app-router-headers'
@@ -1114,6 +1115,12 @@ async function renderToHTMLOrFlightImpl(
       metadata.fetchTags = response.collectedTags.join(',')
     }
 
+    // Let the client router know how long to keep the cached entry around.
+    const staleHeader = String(response.collectedStale)
+    res.setHeader(NEXT_ROUTER_STALE_TIME_HEADER, staleHeader)
+    metadata.headers ??= {}
+    metadata.headers[NEXT_ROUTER_STALE_TIME_HEADER] = staleHeader
+
     // If force static is specifically set to false, we should not revalidate
     // the page.
     if (workStore.forceStatic === false || response.collectedRevalidate === 0) {

diff --git a/packages/next/src/server/use-cache/use-cache-wrapper.ts b/packages/next/src/server/use-cache/use-cache-wrapper.ts
@@ -188,6 +188,7 @@ function generateCacheEntryWithCacheContext(
       'A default cacheLife profile must always be provided. This is a bug in Next.js.'
     )
   }
+
   // Initialize the Store for this Cache entry.
   const cacheStore: UseCacheStore = {
     type: 'cache',
@@ -239,9 +240,15 @@ function propagateCacheLifeAndTags(
         outerTags.push(tag)
       }
     }
+    if (workUnitStore.stale > entry.stale) {
+      workUnitStore.stale = entry.stale
+    }
     if (workUnitStore.revalidate > entry.revalidate) {
       workUnitStore.revalidate = entry.revalidate
     }
+    if (workUnitStore.expire > entry.expire) {
+      workUnitStore.expire = entry.expire
+    }
   }
 }
 

diff --git a/test/e2e/app-dir/use-cache/next.config.js b/test/e2e/app-dir/use-cache/next.config.js
@@ -6,6 +6,7 @@ const nextConfig = {
     dynamicIO: true,
     cacheLife: {
       frequent: {
+        stale: 19,
         revalidate: 100,
       },
     },

diff --git a/test/e2e/app-dir/use-cache/use-cache.test.ts b/test/e2e/app-dir/use-cache/use-cache.test.ts
@@ -98,6 +98,16 @@ describe('use-cache', () => {
       }
     )
 
+    itSkipTurbopack(
+      'should match the expected stale config in the page header',
+      async () => {
+        const meta = JSON.parse(
+          await next.readFile('.next/server/app/cache-tag.meta')
+        )
+        expect(meta.headers['Next-Router-Stale-Time']).toBe('19')
+      }
+    )
+
     itSkipTurbopack(
       'should propagate unstable_cache tags correctly',
       async () => {