Disable 2mb limit for custom incrementalCacheHandler

packages/next/src/server/lib/incremental-cache/index.ts

@@ -65,6 +65,7 @@ export class CacheHandler {
 export class IncrementalCache implements IncrementalCacheType {
   dev?: boolean
   cacheHandler?: CacheHandler
+  hasCustomCacheHandler: boolean
   prerenderManifest: PrerenderManifest
   requestHeaders: Record<string, undefined | string | string[]>
   requestProtocol?: 'http' | 'https'
@@ -112,6 +113,7 @@ export class IncrementalCache implements IncrementalCacheType {
     experimental: { ppr: boolean }
   }) {
     const debug = !!process.env.NEXT_PRIVATE_DEBUG_CACHE
+    this.hasCustomCacheHandler = Boolean(CurCacheHandler)
     if (!CurCacheHandler) {
       if (fs && serverDistDir) {
         if (debug) {
@@ -555,8 +557,14 @@ export class IncrementalCache implements IncrementalCacheType {
     }
 
     if (this.dev && !ctx.fetchCache) return
-    // fetchCache has upper limit of 2MB per-entry currently
-    if (ctx.fetchCache && JSON.stringify(data).length > 2 * 1024 * 1024) {
+    // FetchCache has upper limit of 2MB per-entry currently
+    if (
+      ctx.fetchCache &&
+      // we don't show this error/warning when a custom cache handler is being used
+      // as it might not have this limit
+      this.hasCustomCacheHandler &&
+      JSON.stringify(data).length > 2 * 1024 * 1024
+    ) {
       if (this.dev) {
         throw new Error(`fetch for over 2MB of data can not be cached`)
       }

test/e2e/app-dir/app-static/app-static.test.ts

@@ -516,6 +516,8 @@ createNextDescribe(
             'ssr-forced/page.js',
             'articles/works.rsc',
             'force-cache/page.js',
+            'force-cache/large-data/page.js',
+            'force-cache/large-data/page_client-reference-manifest.js',
             'ssg-draft-mode.html',
             'articles/works.html',
             'no-store/static.rsc',
@@ -533,6 +535,7 @@ createNextDescribe(
             'force-static-fetch-no-store/page_client-reference-manifest.js',
             'force-static/first.rsc',
             'api/draft-mode/route.js',
+            'api/large-data/route.js',
             'blog/tim/first-post.rsc',
             'force-static/first.html',
             'force-static/second.rsc',
@@ -770,6 +773,26 @@ createNextDescribe(
               "initialRevalidateSeconds": false,
               "srcRoute": "/",
             },
+            "/api/large-data": {
+              "dataRoute": null,
+              "experimentalBypassFor": [
+                {
+                  "key": "Next-Action",
+                  "type": "header",
+                },
+                {
+                  "key": "content-type",
+                  "type": "header",
+                  "value": "multipart/form-data",
+                },
+              ],
+              "initialHeaders": {
+                "content-type": "application/json",
+                "x-next-cache-tags": "_N_T_/layout,_N_T_/api/layout,_N_T_/api/large-data/layout,_N_T_/api/large-data/route,_N_T_/api/large-data",
+              },
+              "initialRevalidateSeconds": false,
+              "srcRoute": "/api/large-data",
+            },
             "/articles/works": {
               "dataRoute": "/articles/works.rsc",
               "experimentalBypassFor": [
@@ -3053,6 +3076,12 @@ createNextDescribe(
         expect(next.cliOutput).toContain('cache-handler get')
         expect(next.cliOutput).toContain('cache-handler set')
       })
+
+      it('should load large data only once when using custom cache handler and force-cache mode', async () => {
+        await next.fetch('/force-cache/large-data')
+        await next.fetch('/force-cache/large-data')
+        expect(next.cliOutput.match('Load data').length).toBe(1)
+      })
     }
   }
 )

test/e2e/app-dir/app-static/app/api/large-data/route.js

@@ -0,0 +1,10 @@
+import { NextResponse } from 'next/server'
+
+export async function GET() {
+  console.log('Load data')
+  return NextResponse.json({
+    content: Array.from(new Array(3 * 1024 * 1024))
+      .map(() => 1)
+      .join(''),
+  })
+}

test/e2e/app-dir/app-static/app/force-cache/large-data/page.js

@@ -0,0 +1,13 @@
+export default async function Page() {
+  const resp = await fetch(
+    `http://localhost:${process.env.PORT}/api/large-data`,
+    {
+      cache: 'force-cache',
+    }
+  )
+  const data = await resp.json()
+
+  return <p id="content">{data.content}</p>
+}
+
+export const dynamic = 'force-dynamic'