Impl NonViralNonPostingInvoker; rename other invokers around posting behaviour

include/spinscale/co/nonPostingInvoker.h

@@ -0,0 +1,63 @@
+#ifndef NON_POSTING_INVOKER_H
+#define NON_POSTING_INVOKER_H
+
+#include <config.h>
+#include <coroutine>
+#include <iostream>
+#include <thread>
+#include <utility>
+
+#include <spinscale/co/nonPostingPromise.h>
+
+namespace sscl::co {
+
+template <typename PromiseType>
+class NonPostingInvoker
+{
+public:
+	explicit NonPostingInvoker(PromiseType &_calleePromise) noexcept
+	: calleePromise(_calleePromise)
+	{}
+
+	NonPostingInvoker(const NonPostingInvoker &) = delete;
+	NonPostingInvoker &operator=(const NonPostingInvoker &) = delete;
+
+	NonPostingInvoker(NonPostingInvoker &&other) noexcept
+	: calleePromise(other.calleePromise),
+	ownsFrameDestroy_(std::exchange(other.ownsFrameDestroy_, false))
+	{}
+
+	NonPostingInvoker &operator=(NonPostingInvoker &&other) = delete;
+
+	~NonPostingInvoker() noexcept
+	{
+		if (!ownsFrameDestroy_) { return; }
+
+		std::coroutine_handle<> handle = calleePromise.selfSchedHandle;
+		if (handle) {
+			handle.destroy();
+		}
+	}
+
+	ReturnValues<void> &completedReturnValues() noexcept
+		{ return calleePromise.returnValues; }
+
+	const ReturnValues<void> &completedReturnValues() const noexcept
+		{ return calleePromise.returnValues; }
+
+private:
+	PromiseType &calleePromise;
+
+	/**	Every live invoker owns destruction of its callee coroutine frame in
+	 *	~NonPostingInvoker (via calleePromise.selfSchedHandle).
+	 *
+	 *	The only time frame destruction is skipped is for a moved-from invoker
+	 *	after move construction, so we do not double-destroy the same handle
+	 *	when get_return_object() returns the invoker by value.
+	 */
+	bool ownsFrameDestroy_ = true;
+};
+
+} // namespace sscl::co
+
+#endif // NON_POSTING_INVOKER_H