libs/corosio/src/corosio/src/detail/cached_initiator.hpp

96.2% Lines (25/26) 90.0% Functions (18/20) 100.0% Branches (11/11)

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1			//
2			// Copyright (c) 2024 Vinnie Falco (vinnie.falco@gmail.com)
3			//
4			// Distributed under the Boost Software License, Version 1.0. (See accompanying
5			// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
6			//
7			// Official repository: https://github.com/cppalliance/corosio
8			//
9
10			#ifndef BOOST_COROSIO_DETAIL_CACHED_INITIATOR_HPP
11			#define BOOST_COROSIO_DETAIL_CACHED_INITIATOR_HPP
12
13			#include <coroutine>
14			#include <cstddef>
15
16			namespace boost::corosio::detail {
17
18			/** Cached initiator coroutine frame with RAII cleanup.
19
20			Manages the lifecycle of a cached coroutine frame used for I/O
21			initiator coroutines. Automatically destroys the coroutine handle
22			and frees the cached frame memory on destruction.
23			*/
24			struct cached_initiator
25			{
26			void* frame = nullptr;
27			std::coroutine_handle<> handle;
28
29		20092	~cached_initiator()
30			{
31	2/2 ✓ Branch 1 taken 78 times. ✓ Branch 2 taken 20014 times.	20092	if (handle)
32		78	handle.destroy();
33	2/2 ✓ Branch 0 taken 78 times. ✓ Branch 1 taken 20014 times.	20092	if (frame)
34		78	::operator delete(frame);
35		20092	}
36
37		20092	cached_initiator() = default;
38			cached_initiator(cached_initiator const&) = delete;
39			cached_initiator& operator=(cached_initiator const&) = delete;
40
41			/** Start initiator coroutine that calls Fn on impl.
42
43			Destroys any existing coroutine, creates a new initiator that
44			will call the specified member function, and returns the handle
45			for symmetric transfer.
46
47			@tparam Fn Member function pointer to call (e.g., &Impl::do_read_io)
48			@param impl Pointer to the I/O object implementation
49			@return Coroutine handle for symmetric transfer
50			*/
51			template<auto Fn, class Impl>
52		230235	std::coroutine_handle<> start(Impl* impl)
53			{
54	2/2 ✓ Branch 1 taken 230157 times. ✓ Branch 2 taken 78 times.	230235	if (handle)
55	1/1 ✓ Branch 1 taken 230157 times.	230157	handle.destroy();
56	1/1 ✓ Branch 1 taken 230235 times.	230235	auto initiator = make_initiator_coro<Fn>(frame, impl);
57		230235	handle = initiator.h;
58		460470	return initiator.h;
59			}
60
61			private:
62			template<class Impl, auto Fn>
63			struct initiator_coro
64			{
65			struct promise_type
66			{
67			Impl* impl;
68
69		230235	static void* operator new(std::size_t n, void& cached, Impl)
70			{
71	2/2 ✓ Branch 0 taken 78 times. ✓ Branch 1 taken 230157 times.	230235	if (!cached)
72		78	cached = ::operator new(n);
73		230235	return cached;
74			}
75
76		230235	static void operator delete(void*) noexcept {}
77
78		230235	std::suspend_always initial_suspend() noexcept { return {}; }
79		230235	std::suspend_always final_suspend() noexcept { return {}; }
80
81		230235	initiator_coro get_return_object()
82			{
83		230235	return {std::coroutine_handle<promise_type>::from_promise(*this)};
84			}
85
86		230235	void return_void() {}
87		✗	void unhandled_exception() { std::terminate(); }
88			};
89
90			using handle_type = std::coroutine_handle<promise_type>;
91			handle_type h;
92			};
93
94			template<auto Fn, class Impl>
95	1/1 ✓ Branch 1 taken 230235 times.	230235	static initiator_coro<Impl, Fn> make_initiator_coro(void&, Impl impl)
96			{
97			(impl->*Fn)();
98			co_return;
99		460470	}
100			};
101
102			} // namespace boost::corosio::detail
103
104			#endif
105