[Cache Components] Allow sync IO inside console methods

console methods may be patched to do things like add a timestamp to the log row. While we can't determine the meaning of readin the current time in arbitrary contexts we can know with reasonable certainty that any sync IO inside a console method is not being used in the logical output of the program. To account for this we can make a special affordance for sync IO inside of these methods that allows them to run without interrupting the prerender early.

Originall I wanted to make it so that even if you patch these methods in userland we can still exit the context but it turns out this is very complex and difficult because we have many patches layered together and they need to run in the correct order. So essentially this just permits sync IO in the preexisting implementations of the console methods. This is probably sufficient since typically these methods aren't patched in userspace but in the runtime host itself. If we recieve feedback that this is insufficient we can consider alternative later.

The original implementation exited the workUnitAsyncStorage but it turns out that some console methods like assert call others from their internal implementation. This means that you lose the context at the top of the patch stack for things like dimming console logs if you do this. Instead we simply set a temporary flag to allow sync IO during the a portion of the prerender. It is important to guard this with a try/finally and always synchronously otherwise you can accidentally and racily allow sync IO in other parts of the program that you did not intend

Author: gnoff

packages/next/src/server/app-render/work-unit-async-storage.external.ts

@@ -192,6 +192,14 @@ interface PrerenderStoreModernCommon
    */
   readonly hmrRefreshHash: string | undefined
 
+  /**
+   * For certain special case synchronous operations we allow the temporary disabling of
+   * sync IO aborting. This must always be used in a try/finally block to ensure that the
+   * original behavior is restored before exiting the sync block. If you aren't sure if you
+   * should use this then ask first.
+   */
+  allowSyncIO?: boolean
+
   /**
    * Only available in dev mode.
    */