clear pending timeout after promise.race (#5701)

* clear pending timeout after promise.race

* Create cool-toys-marry.md

* fix lint errors

* formatting

Author: Feiyang1

.changeset/cool-toys-marry.md

@@ -0,0 +1,5 @@
+---
+"@firebase/functions": patch
+---
+
+Clear pending timeout after promise.race. It allows the process to exit immediately in case the SDK is used in Node.js, otherwise the process will wait for the timeout to finish before exiting. 

packages/functions/src/service.ts

@@ -53,18 +53,34 @@ export interface HttpResponseBody {
   };
 }
 
+interface CancellablePromise<T> {
+  promise: Promise<T>;
+  cancel: () => void;
+}
+
 /**
  * Returns a Promise that will be rejected after the given duration.
  * The error will be of type FunctionsError.
  *
  * @param millis Number of milliseconds to wait before rejecting.
  */
-function failAfter(millis: number): Promise<never> {
-  return new Promise((_, reject) => {
-    setTimeout(() => {
-      reject(new FunctionsError('deadline-exceeded', 'deadline-exceeded'));
-    }, millis);
-  });
+function failAfter(millis: number): CancellablePromise<never> {
+  // Node timers and browser timers are fundamentally incompatible, but we
+  // don't care about the value here
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  let timer: any | null = null;
+  return {
+    promise: new Promise((_, reject) => {
+      timer = setTimeout(() => {
+        reject(new FunctionsError('deadline-exceeded', 'deadline-exceeded'));
+      }, millis);
+    }),
+    cancel: () => {
+      if (timer) {
+        clearTimeout(timer);
+      }
+    }
+  };
 }
 
 /**
@@ -247,12 +263,16 @@ async function call(
   // Default timeout to 70s, but let the options override it.
   const timeout = options.timeout || 70000;
 
+  const failAfterHandle = failAfter(timeout);
   const response = await Promise.race([
     postJSON(url, body, headers, functionsInstance.fetchImpl),
-    failAfter(timeout),
+    failAfterHandle.promise,
     functionsInstance.cancelAllRequests
   ]);
 
+  // Always clear the failAfter timeout
+  failAfterHandle.cancel();
+
   // If service was deleted, interrupted response throws an error.
   if (!response) {
     throw new FunctionsError(