allow for finish to be passed in callback

Author: AbhiPrasad

packages/core/src/tracing/trace.ts

@@ -143,7 +143,16 @@ export function startActiveSpan<T>(context: TransactionContext, callback: (span:
 
 /**
  * Similar to `Sentry.startActiveSpan`. Wraps a function with a transaction/span, but does not finish the span
- * after the function is done automatically.
+ * after the function is done automatically. Use the returned `finish` function to finish the span.
+ *
+ * ```js
+ * Sentry.startActiveSpan({ name: 'foo' }, (span, finish) => {
+ *   // do work here
+ *   res.on('finish', () => {
+ *     finish();
+ *   });
+ * });
+ * ```
  *
  * The created span is the active span and will be used as parent by other spans created inside the function
  * and can be accessed via `Sentry.getSpan()`, as long as the function is executed while the scope is active.
@@ -152,7 +161,10 @@ export function startActiveSpan<T>(context: TransactionContext, callback: (span:
  * or you didn't set `tracesSampleRate`, this function will not generate spans
  * and the `span` returned from the callback will be undefined.
  */
-export function startActiveSpanManual<T>(context: TransactionContext, callback: (span: Span | undefined) => T): T {
+export function startActiveSpanManual<T>(
+  context: TransactionContext,
+  callback: (span: Span | undefined, finish: () => void) => T,
+): T {
   const ctx = { ...context };
   // If a name is set and a description is not, set the description to the name.
   if (ctx.name !== undefined && ctx.description === undefined) {
@@ -174,9 +186,14 @@ export function startActiveSpanManual<T>(context: TransactionContext, callback:
   const activeSpan = getChildSpanOrTransaction();
   scope.setSpan(activeSpan);
 
+  function finishAndSetSpan(): void {
+    activeSpan && activeSpan.finish();
+    hub.getScope().setSpan(parentSpan);
+  }
+
   let maybePromiseResult: T;
   try {
-    maybePromiseResult = callback(activeSpan);
+    maybePromiseResult = callback(activeSpan, finishAndSetSpan);
   } catch (e) {
     activeSpan && activeSpan.setStatus('internal_error');
     throw e;