include/boost/corosio/native/detail/reactor/reactor_signal_pipe.hpp
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boost::corosio::detail::reactor_signal_pipe_reader::drain_op::perform_io()
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boost::corosio::detail::reactor_signal_pipe_reader::drain_op::operator()()
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boost::corosio::detail::reactor_signal_pipe_reader::drain_op::destroy()
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boost::corosio::detail::reactor_signal_pipe_reader::arm()
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| Line | TLA | Hits | Source Code |
|---|---|---|---|
| 1 | // | ||
| 2 | // Copyright (c) 2026 Michael Vandeberg | ||
| 3 | // | ||
| 4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | ||
| 5 | // file LICENSE_1_0.txt 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_NATIVE_DETAIL_REACTOR_REACTOR_SIGNAL_PIPE_HPP | ||
| 11 | #define BOOST_COROSIO_NATIVE_DETAIL_REACTOR_REACTOR_SIGNAL_PIPE_HPP | ||
| 12 | |||
| 13 | #include <boost/corosio/detail/platform.hpp> | ||
| 14 | |||
| 15 | #if BOOST_COROSIO_POSIX | ||
| 16 | |||
| 17 | #include <boost/corosio/native/detail/posix/posix_signal_service.hpp> | ||
| 18 | #include <boost/corosio/native/detail/reactor/reactor_descriptor_state.hpp> | ||
| 19 | #include <boost/corosio/native/detail/reactor/reactor_op_base.hpp> | ||
| 20 | |||
| 21 | #include <errno.h> | ||
| 22 | |||
| 23 | /* | ||
| 24 | Reactor signal-pipe reader | ||
| 25 | ========================== | ||
| 26 | |||
| 27 | Bridges the global POSIX signal self-pipe (see posix_signal_service.hpp) | ||
| 28 | to the reactor backends (epoll/kqueue/select). The concrete scheduler owns | ||
| 29 | one of these for its lifetime and, in register_signal_reader(), parks the | ||
| 30 | drain op as the descriptor's read_op then calls register_descriptor(). | ||
| 31 | |||
| 32 | On each read-readiness edge the drain op completes without touching the | ||
| 33 | pipe, and invoke_deferred_io runs it once the descriptor lock is | ||
| 34 | released. Only then does it drain the pipe and deliver the signals: | ||
| 35 | delivery posts into every context watching the pipe, and a post made | ||
| 36 | under this descriptor's lock would order it before another context's | ||
| 37 | scheduler lock, the reverse of that scheduler's own order. The op then | ||
| 38 | parks itself again, draining once more if an edge arrived meanwhile. | ||
| 39 | */ | ||
| 40 | |||
| 41 | namespace boost::corosio::detail { | ||
| 42 | |||
| 43 | struct reactor_signal_pipe_reader | ||
| 44 | { | ||
| 45 | struct drain_op final : reactor_op_base | ||
| 46 | { | ||
| 47 | reactor_signal_pipe_reader* reader = nullptr; | ||
| 48 | |||
| 49 | 833x | void perform_io() noexcept override | |
| 50 | { | ||
| 51 | 833x | errn = 0; | |
| 52 | 833x | } | |
| 53 | |||
| 54 | 833x | void operator()() override | |
| 55 | { | ||
| 56 | 833x | auto& desc = reader->desc; | |
| 57 | for (;;) | ||
| 58 | { | ||
| 59 | 833x | posix_signal_detail::drain_signal_pipe(); | |
| 60 | 833x | conditionally_enabled_mutex::scoped_lock lock(desc.mutex); | |
| 61 | // An edge seen while unparked set read_ready instead. | ||
| 62 | 833x | if (!desc.read_ready) | |
| 63 | { | ||
| 64 | 833x | desc.read_op = this; | |
| 65 | 833x | break; | |
| 66 | } | ||
| 67 | ✗ | desc.read_ready = false; | |
| 68 | 833x | } | |
| 69 | // A select() started while this op was out ran without the | ||
| 70 | // pipe in its read set. | ||
| 71 | 833x | desc.scheduler_->notify_reparked(); | |
| 72 | // Nothing counted this op as work; balance the decrement | ||
| 73 | // that follows the inline run of a completed op. | ||
| 74 | 833x | desc.scheduler_->compensating_work_started(); | |
| 75 | 833x | } | |
| 76 | |||
| 77 | ✗ | void destroy() override {} | |
| 78 | }; | ||
| 79 | |||
| 80 | reactor_descriptor_state desc; | ||
| 81 | drain_op op; | ||
| 82 | |||
| 83 | // Park the drain op and return the descriptor to hand to | ||
| 84 | // scheduler::register_descriptor(read_fd, ...). | ||
| 85 | 559x | reactor_descriptor_state* arm() noexcept | |
| 86 | { | ||
| 87 | 559x | op.reader = this; | |
| 88 | 559x | desc.read_op = &op; | |
| 89 | 559x | return &desc; | |
| 90 | } | ||
| 91 | }; | ||
| 92 | |||
| 93 | } // namespace boost::corosio::detail | ||
| 94 | |||
| 95 | #endif // BOOST_COROSIO_POSIX | ||
| 96 | |||
| 97 | #endif // BOOST_COROSIO_NATIVE_DETAIL_REACTOR_REACTOR_SIGNAL_PIPE_HPP | ||
| 98 |