Libspinscale: begin splitting it off

libspinscale/include/spinscale/asynchronousContinuationChainLink.h

@@ -0,0 +1,32 @@
+#ifndef ASYNCHRONOUS_CONTINUATION_CHAIN_LINK_H
+#define ASYNCHRONOUS_CONTINUATION_CHAIN_LINK_H
+
+#include <memory>
+
+namespace smo {
+
+/**
+ * @brief Base class for all asynchronous continuation chain links
+ *
+ * This non-template base class provides type erasure for the continuation
+ * chain, allowing RTTI and dynamic casting when walking the chain.
+ *
+ * The chain walking logic can use dynamic_cast to determine the most
+ * derived type and perform appropriate operations.
+ *
+ * Inherits from enable_shared_from_this to allow objects to obtain a
+ * shared_ptr to themselves, which is useful for gridlock detection tracking.
+ */
+class AsynchronousContinuationChainLink
+:	public std::enable_shared_from_this<AsynchronousContinuationChainLink>
+{
+public:
+    virtual ~AsynchronousContinuationChainLink() = default;
+
+	virtual std::shared_ptr<AsynchronousContinuationChainLink>
+	getCallersContinuationShPtr() const = 0;
+};
+
+} // namespace smo
+
+#endif // ASYNCHRONOUS_CONTINUATION_CHAIN_LINK_H