From dbc9569775f71af2e1250b3cbf83ba4503078325 Mon Sep 17 00:00:00 2001
From: Hayodea Hakol <hayodea@protonmail.com>
Date: Sun, 21 Sep 2025 14:17:23 -0400
Subject: [PATCH] Async: Add exception bubbling

CONT_SET_EXC: Set exception on the continuation, to be rethrown
	by the caller.
CONT_SET_EXC_AND_RET: Convenience which returns immediately
	after setting the exception.
---
 include/asynchronousContinuation.h           | 32 ++++++++++++++++++++
 include/serializedAsynchronousContinuation.h |  1 -
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/include/asynchronousContinuation.h b/include/asynchronousContinuation.h
index 95f2793..407318d 100644
--- a/include/asynchronousContinuation.h
+++ b/include/asynchronousContinuation.h
@@ -3,9 +3,11 @@
 
 #include <functional>
 #include <memory>
+#include <exception>
 #include <componentThread.h>
 #include <lockSet.h>
 
+
 namespace smo {
 
 /**
@@ -33,8 +35,38 @@ public:
 		std::shared_ptr<AsynchronousContinuation<OriginalCbFnT>>
 			lifetimePreservingConveyance);
 
+
+	/**	EXPLANATION:
+	 * When an exception is thrown in a an async callee, which pertains to an
+	 * error in the data given by the caller, we ought not to throw the
+	 * exception within the callee. Instead, we should store the exception
+	 * in the continuation object and return it to the caller.
+	 *
+	 * The caller should then call checkException() to rethrow it on its
+	 * own stack.
+	 *
+	 * This macro should be used by the caller to bubble the exception to the
+	 * caller.
+	 */
+	#define CONT_SET_EXC(continuation, type, exc_obj) \
+		(continuation)->exception = std::make_exception_ptr<type>(exc_obj)
+
+	#define CONT_SET_EXC_AND_RET(continuation, type, exc_obj) \
+		do { \
+			(continuation)->exception = std::make_exception_ptr<type>(exc_obj); \
+			return; \
+		} while(0)
+
+	// Call this in the caller to rethrow the exception.
+	void checkException()
+	{
+		if (exception)
+			{ std::rethrow_exception(exception); }
+	}
+
 public:
 	OriginalCbFnT originalCbFn;
+	std::exception_ptr exception;
 };
 
 /**
diff --git a/include/serializedAsynchronousContinuation.h b/include/serializedAsynchronousContinuation.h
index e632ebf..a8cded8 100644
--- a/include/serializedAsynchronousContinuation.h
+++ b/include/serializedAsynchronousContinuation.h
@@ -11,7 +11,6 @@
 
 namespace smo {
 
-
 template <class OriginalCbFnT>
 class SerializedAsynchronousContinuation
 :	public PostedAsynchronousContinuation<OriginalCbFnT>