[ppr] Resume Data Cache (#72161)

This adds a new ResumeDataCache concept to Next.js. This cache is persisted during production, and used for pre-seeding during development. Every route will generate its own resume data cache that will be used when partial prerendering is enabled. This lets us fill the caches during the prerender, and re-use those cache entries every time the page is resumed. This allows a future where we can reuse stale static shells while also reusing the resume data cache.

packages/next/src/export/routes/app-page.ts

@@ -16,6 +16,7 @@ import {
   RSC_SUFFIX,
   RSC_SEGMENTS_DIR_SUFFIX,
   RSC_SEGMENT_SUFFIX,
+  NEXT_STATIC_DATA_CACHE_SUFFIX,
 } from '../../lib/constants'
 import { hasNextSupport } from '../../server/ci-info'
 import { lazyRenderAppPage } from '../../server/route-modules/app-page/module.render'
@@ -27,6 +28,7 @@ import type { WorkStore } from '../../server/app-render/work-async-storage.exter
 import type { FallbackRouteParams } from '../../server/request/fallback-params'
 import { AfterRunner } from '../../server/after/run-with-after'
 import type { RequestLifecycleOpts } from '../../server/base-server'
+import { stringifyResumeDataCache } from '../../server/resume-data-cache/serialization'
 
 export const enum ExportedAppPageFiles {
   HTML = 'HTML',
@@ -35,6 +37,7 @@ export const enum ExportedAppPageFiles {
   PREFETCH_FLIGHT_SEGMENT = 'PREFETCH_FLIGHT_SEGMENT',
   META = 'META',
   POSTPONED = 'POSTPONED',
+  RESUME_CACHE = 'RESUME_CACHE',
 }
 
 export async function prospectiveRenderAppPage(
@@ -66,7 +69,9 @@ export async function prospectiveRenderAppPage(
         waitUntil: afterRunner.context.waitUntil,
         onClose: afterRunner.context.onClose,
         onAfterTaskError: afterRunner.context.onTaskError,
-      }
+      },
+      undefined,
+      false
     )
 
     // TODO(after): if we abort a prerender because of an error in an after-callback
@@ -126,7 +131,9 @@ export async function exportAppPage(
       pathname,
       query,
       fallbackRouteParams,
-      renderOpts
+      renderOpts,
+      undefined,
+      false
     )
 
     const html = result.toUnchunkedString()
@@ -143,6 +150,7 @@ export async function exportAppPage(
       fetchTags,
       fetchMetrics,
       segmentFlightData,
+      immutableResumeDataCache,
     } = metadata
 
     // Ensure we don't postpone without having PPR enabled.
@@ -249,6 +257,14 @@ export async function exportAppPage(
       'utf8'
     )
 
+    if (immutableResumeDataCache) {
+      await fileWriter(
+        ExportedAppPageFiles.RESUME_CACHE,
+        htmlFilepath.replace(/\.html$/, NEXT_STATIC_DATA_CACHE_SUFFIX),
+        await stringifyResumeDataCache(immutableResumeDataCache)
+      )
+    }
+
     const isParallelRoute = /\/@\w+/.test(page)
     const isNonSuccessfulStatusCode = res.statusCode > 300
 

packages/next/src/export/worker.ts

@@ -46,7 +46,6 @@ import {
   type FallbackRouteParams,
 } from '../server/request/fallback-params'
 import { needsExperimentalReact } from '../lib/needs-experimental-react'
-import { runWithCacheScope } from '../server/async-storage/cache-scope.external'
 import type { AppRouteRouteModule } from '../server/route-modules/app-route/module.compiled'
 import { isStaticGenBailoutError } from '../client/components/static-generation-bailout'
 
@@ -468,26 +467,21 @@ export async function exportPages(
 
     return { result, path, pageKey }
   }
-  // for each build worker we share one dynamic IO cache scope
-  // this is only leveraged if the flag is enabled
-  const dynamicIOCacheScope = new Map()
 
-  await runWithCacheScope({ cache: dynamicIOCacheScope }, async () => {
-    for (let i = 0; i < paths.length; i += maxConcurrency) {
-      const subset = paths.slice(i, i + maxConcurrency)
+  for (let i = 0; i < paths.length; i += maxConcurrency) {
+    const subset = paths.slice(i, i + maxConcurrency)
 
-      const subsetResults = await Promise.all(
-        subset.map((path) =>
-          exportPageWithRetry(
-            path,
-            nextConfig.experimental.staticGenerationRetryCount ?? 1
-          )
+    const subsetResults = await Promise.all(
+      subset.map((path) =>
+        exportPageWithRetry(
+          path,
+          nextConfig.experimental.staticGenerationRetryCount ?? 1
         )
       )
+    )
 
-      results.push(...subsetResults)
-    }
-  })
+    results.push(...subsetResults)
+  }
 
   return results
 }

packages/next/src/lib/constants.ts

@@ -16,6 +16,7 @@ export const ACTION_SUFFIX = '.action'
 export const NEXT_DATA_SUFFIX = '.json'
 export const NEXT_META_SUFFIX = '.meta'
 export const NEXT_BODY_SUFFIX = '.body'
+export const NEXT_STATIC_DATA_CACHE_SUFFIX = '.rdc.json'
 
 export const NEXT_CACHE_TAGS_HEADER = 'x-next-cache-tags'
 export const NEXT_CACHE_SOFT_TAGS_HEADER = 'x-next-cache-soft-tags'