From b7516a13929c66ea56cffa5443dbebf13c2b58f7 Mon Sep 17 00:00:00 2001
From: Daniel Roe <daniel@roe.dev>
Date: Fri, 8 Mar 2024 17:03:38 +0000
Subject: [PATCH] fix(nuxt): access prerender cache synchronously (#26146)

---
 packages/nuxt/src/app/composables/asyncData.ts   |  6 +++---
 packages/nuxt/src/app/nuxt.ts                    |  2 +-
 packages/nuxt/src/core/nitro.ts                  |  4 +++-
 packages/nuxt/src/core/runtime/nitro/renderer.ts | 13 +++++++------
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/packages/nuxt/src/app/composables/asyncData.ts b/packages/nuxt/src/app/composables/asyncData.ts
index 79a7813ba9..f5c2c18a16 100644
--- a/packages/nuxt/src/app/composables/asyncData.ts
+++ b/packages/nuxt/src/app/composables/asyncData.ts
@@ -214,9 +214,9 @@ export function useAsyncData<
   const nuxtApp = useNuxtApp()
 
   // When prerendering, share payload data automatically between requests
-  const handler = import.meta.client || !import.meta.prerender || !nuxtApp.ssrContext?._sharedPrerenderCache ? _handler : async () => {
-    const value = await nuxtApp.ssrContext!._sharedPrerenderCache!.get(key)
-    if (value) { return value as ResT }
+  const handler = import.meta.client || !import.meta.prerender || !nuxtApp.ssrContext?._sharedPrerenderCache ? _handler : () => {
+    const value = nuxtApp.ssrContext!._sharedPrerenderCache!.get(key)
+    if (value) { return value as Promise<ResT> }
 
     const promise = nuxtApp.runWithContext(_handler)
     nuxtApp.ssrContext!._sharedPrerenderCache!.set(key, promise)
diff --git a/packages/nuxt/src/app/nuxt.ts b/packages/nuxt/src/app/nuxt.ts
index ce515d6a8b..8c069985ba 100644
--- a/packages/nuxt/src/app/nuxt.ts
+++ b/packages/nuxt/src/app/nuxt.ts
@@ -73,7 +73,7 @@ export interface NuxtSSRContext extends SSRContext {
   _payloadReducers: Record<string, (data: any) => any>
   /** @internal */
   _sharedPrerenderCache?: {
-    get<T = unknown> (key: string): Promise<T>
+    get<T = unknown> (key: string): Promise<T> | undefined
     set<T> (key: string, value: Promise<T>): Promise<void>
   }
 }
diff --git a/packages/nuxt/src/core/nitro.ts b/packages/nuxt/src/core/nitro.ts
index 9bb9fddfa9..e2a1ee456a 100644
--- a/packages/nuxt/src/core/nitro.ts
+++ b/packages/nuxt/src/core/nitro.ts
@@ -393,10 +393,12 @@ export async function initNitro (nuxt: Nuxt & { _nitro?: Nitro }) {
     }
   })
 
+  const cacheDir = resolve(nuxt.options.buildDir, 'cache/nitro/prerender')
+  await fsp.rm(cacheDir, { recursive: true, force: true }).catch(() => {})
   nitro.options._config.storage = defu(nitro.options._config.storage, {
     'internal:nuxt:prerender': {
       driver: pathToFileURL(await resolvePath(join(distDir, 'core/runtime/nitro/cache-driver'))).href,
-      base: resolve(nuxt.options.buildDir, 'cache/nitro/prerender')
+      base: cacheDir
     }
   })
 
diff --git a/packages/nuxt/src/core/runtime/nitro/renderer.ts b/packages/nuxt/src/core/runtime/nitro/renderer.ts
index 3d262a1e3d..e1fabfb458 100644
--- a/packages/nuxt/src/core/runtime/nitro/renderer.ts
+++ b/packages/nuxt/src/core/runtime/nitro/renderer.ts
@@ -185,16 +185,17 @@ const payloadCache = import.meta.prerender ? useStorage('internal:nuxt:prerender
 const islandCache = import.meta.prerender ? useStorage('internal:nuxt:prerender:island') : null
 const islandPropCache = import.meta.prerender ? useStorage('internal:nuxt:prerender:island-props') : null
 const sharedPrerenderPromises = import.meta.prerender && process.env.NUXT_SHARED_DATA ? new Map<string, Promise<any>>() : null
+const sharedPrerenderKeys = new Set<string>()
 const sharedPrerenderCache = import.meta.prerender && process.env.NUXT_SHARED_DATA ? {
-  get <T = unknown>(key: string): Promise<T> {
-    if (sharedPrerenderPromises!.has(key)) {
-      return sharedPrerenderPromises!.get(key)!
+  get <T = unknown>(key: string): Promise<T> | undefined {
+    if (sharedPrerenderKeys.has(key)) {
+      return sharedPrerenderPromises!.get(key) ?? useStorage('internal:nuxt:prerender:shared').getItem(key) as Promise<T>
     }
-    return useStorage('internal:nuxt:prerender:shared').getItem(key) as Promise<T>
   },
-  async set <T>(key: string, value: Promise<T>) {
+  async set <T>(key: string, value: Promise<T>): Promise<void> {
+    sharedPrerenderKeys.add(key)
     sharedPrerenderPromises!.set(key, value)
-    return useStorage('internal:nuxt:prerender:shared').setItem(key, await value as any)
+    useStorage('internal:nuxt:prerender:shared').setItem(key, await value as any)
       // free up memory after the promise is resolved
       .finally(() => sharedPrerenderPromises!.delete(key))
   },