From c8621b3a35bc86653d933b20d80234ca1b694511 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eduardo=20Bou=C3=A7as?= <mail@eduardoboucas.com>
Date: Thu, 20 Jun 2024 11:30:43 +0100
Subject: [PATCH 1/2] feat: add central cache directive

---
 src/run/handlers/server.ts | 7 ++++++-
 src/run/headers.ts         | 7 +++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/run/handlers/server.ts b/src/run/handlers/server.ts
index c63cfcd42d..404e413061 100644
--- a/src/run/handlers/server.ts
+++ b/src/run/handlers/server.ts
@@ -48,6 +48,9 @@ const disableFaultyTransferEncodingHandling = (res: ComputeJsOutgoingMessage) =>
 // TODO: remove once https://github.com/netlify/serverless-functions-api/pull/219
 // is released and public types are updated
 interface FutureContext extends Context {
+  flags: {
+    get: (name: string) => boolean
+  },
   waitUntil?: (promise: Promise<unknown>) => void
 }
 
@@ -123,7 +126,9 @@ export default async (request: Request, context: FutureContext) => {
 
     await adjustDateHeader({ headers: response.headers, request, span, tracer, requestContext })
 
-    setCacheControlHeaders(response.headers, request, requestContext)
+    const useCentralCache = context.flags.get("serverless_functions_nextjs_central_cache")
+
+    setCacheControlHeaders(response.headers, request, requestContext, useCentralCache)
     setCacheTagsHeaders(response.headers, request, tagsManifest, requestContext)
     setVaryHeaders(response.headers, request, nextConfig)
     setCacheStatusHeader(response.headers)
diff --git a/src/run/headers.ts b/src/run/headers.ts
index 53b0137074..5d1680e400 100644
--- a/src/run/headers.ts
+++ b/src/run/headers.ts
@@ -220,7 +220,10 @@ export const setCacheControlHeaders = (
   headers: Headers,
   request: Request,
   requestContext: RequestContext,
+  useCentralCache: boolean
 ) => {
+  const centralCacheDirective = useCentralCache ? ', persist' : ''
+
   if (
     typeof requestContext.routeHandlerRevalidate !== 'undefined' &&
     ['GET', 'HEAD'].includes(request.method) &&
@@ -232,7 +235,7 @@ export const setCacheControlHeaders = (
       // if we are serving already stale response, instruct edge to not attempt to cache that response
       headers.get('x-nextjs-cache') === 'STALE'
         ? 'public, max-age=0, must-revalidate'
-        : `s-maxage=${requestContext.routeHandlerRevalidate === false ? 31536000 : requestContext.routeHandlerRevalidate}, stale-while-revalidate=31536000`
+        : `s-maxage=${requestContext.routeHandlerRevalidate === false ? 31536000 : requestContext.routeHandlerRevalidate}, stale-while-revalidate=31536000${centralCacheDirective}`
 
     headers.set('netlify-cdn-cache-control', cdnCacheControl)
     return
@@ -259,7 +262,7 @@ export const setCacheControlHeaders = (
           )
 
     headers.set('cache-control', browserCacheControl || 'public, max-age=0, must-revalidate')
-    headers.set('netlify-cdn-cache-control', cdnCacheControl)
+    headers.set('netlify-cdn-cache-control', cdnCacheControl + centralCacheDirective)
     return
   }
 

From 00975374aa03961756781e547eecd5334522fa7d Mon Sep 17 00:00:00 2001
From: eduardoboucas <eduardoboucas@users.noreply.github.com>
Date: Thu, 20 Jun 2024 10:35:42 +0000
Subject: [PATCH 2/2] chore: format with prettier

---
 src/run/handlers/server.ts | 4 ++--
 src/run/headers.ts         | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/run/handlers/server.ts b/src/run/handlers/server.ts
index 404e413061..11235ba74b 100644
--- a/src/run/handlers/server.ts
+++ b/src/run/handlers/server.ts
@@ -50,7 +50,7 @@ const disableFaultyTransferEncodingHandling = (res: ComputeJsOutgoingMessage) =>
 interface FutureContext extends Context {
   flags: {
     get: (name: string) => boolean
-  },
+  }
   waitUntil?: (promise: Promise<unknown>) => void
 }
 
@@ -126,7 +126,7 @@ export default async (request: Request, context: FutureContext) => {
 
     await adjustDateHeader({ headers: response.headers, request, span, tracer, requestContext })
 
-    const useCentralCache = context.flags.get("serverless_functions_nextjs_central_cache")
+    const useCentralCache = context.flags.get('serverless_functions_nextjs_central_cache')
 
     setCacheControlHeaders(response.headers, request, requestContext, useCentralCache)
     setCacheTagsHeaders(response.headers, request, tagsManifest, requestContext)
diff --git a/src/run/headers.ts b/src/run/headers.ts
index 5d1680e400..6f11ec88da 100644
--- a/src/run/headers.ts
+++ b/src/run/headers.ts
@@ -220,7 +220,7 @@ export const setCacheControlHeaders = (
   headers: Headers,
   request: Request,
   requestContext: RequestContext,
-  useCentralCache: boolean
+  useCentralCache: boolean,
 ) => {
   const centralCacheDirective = useCentralCache ? ', persist' : ''