feat(core): add cloudflare flushing logic to core util

Author: logaretm

packages/core/src/utils/cloudflareWaitUntil.ts

@@ -0,0 +1,35 @@
+import { GLOBAL_OBJ } from './worldwide';
+
+export type MinimalCloudflareContext = {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  waitUntil(promise: Promise<any>): void;
+};
+
+export const CloudflareContextKey = '__cloudflare-context__';
+
+/**
+ * Function that delays closing of a Cloudflare lambda until the provided promise is resolved.
+ */
+export function cloudflareWaitUntil(task: Promise<unknown>): boolean {
+  try {
+    const cfContextSymbol = Symbol.for(CloudflareContextKey);
+    const globalWithCfContext = GLOBAL_OBJ as typeof GLOBAL_OBJ & {
+      [cfContextSymbol]: {
+        ctx: MinimalCloudflareContext;
+      };
+    };
+
+    const context = globalWithCfContext[cfContextSymbol].ctx;
+
+    if (typeof context.waitUntil === 'function') {
+      // eslint-disable-next-line no-console
+      console.log('flushing with cf');
+      context.waitUntil(task);
+      return true;
+    }
+
+    return false;
+  } catch {
+    return false;
+  }
+}

packages/core/src/utils/flushIfServerless.ts

@@ -1,13 +1,9 @@
 import { flush } from '../exports';
+import { type MinimalCloudflareContext, CloudflareContextKey, cloudflareWaitUntil } from './cloudflareWaitUntil';
 import { debug } from './debug-logger';
 import { vercelWaitUntil } from './vercelWaitUntil';
 import { GLOBAL_OBJ } from './worldwide';
 
-type MinimalCloudflareContext = {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  waitUntil(promise: Promise<any>): void;
-};
-
 async function flushWithTimeout(timeout: number): Promise<void> {
   try {
     debug.log('Flushing events...');
@@ -58,6 +54,14 @@ export async function flushIfServerless(
     return;
   }
 
+  // @ts-expect-error This is not typed
+  if (GLOBAL_OBJ[Symbol.for(CloudflareContextKey)]) {
+    // If the cloudflareWaitUntil function is available, use it to flush the events, if not then fallback to the regular flush
+    if (cloudflareWaitUntil(flushWithTimeout(timeout))) {
+      return;
+    }
+  }
+
   if (typeof process === 'undefined') {
     return;
   }