Index/include / boost / corosio / detail / scheduler.hpp

include/boost/corosio/detail/scheduler.hpp

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scheduler.hpp
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Function Calls Lines Blocks
boost::corosio::detail::scheduler::~scheduler() :35 1876x 100.0% 100.0% boost::corosio::detail::scheduler::register_signal_reader(int) :98 0 0.0% 0.0% boost::corosio::detail::scheduler::scheduler_locking_disabled() const :115 0 0.0% 0.0% boost::corosio::detail::scheduler::configure_threading(boost::corosio::detail::scheduler::threading_config) :118 0 0.0% 0.0%
Line TLA Hits Source Code
1 //
2 // Copyright (c) 2025 Vinnie Falco ([email protected])
3 // Copyright (c) 2026 Steve Gerbino
4 // Copyright (c) 2026 Michael Vandeberg
5 //
6 // Distributed under the Boost Software License, Version 1.0. (See accompanying
7 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8 //
9 // Official repository: https://github.com/cppalliance/corosio
10 //
11
12 #ifndef BOOST_COROSIO_DETAIL_SCHEDULER_HPP
13 #define BOOST_COROSIO_DETAIL_SCHEDULER_HPP
14
15 #include <boost/corosio/detail/config.hpp>
16 #include <boost/capy/continuation.hpp>
17 #include <coroutine>
18
19 #include <cstddef>
20
21 namespace boost::corosio::detail {
22
23 class scheduler_op;
24
25 /** Define the abstract interface for the event loop scheduler.
26
27 Concrete backends (epoll, IOCP, kqueue, select) derive from
28 this to implement the reactor/proactor event loop. The
29 @ref io_context delegates all scheduling operations here.
30
31 @see io_context
32 */
33 struct BOOST_COROSIO_DECL scheduler
34 {
35 1876x virtual ~scheduler() = default;
36
37 /// Post a coroutine handle for deferred execution.
38 virtual void post(std::coroutine_handle<>) const = 0;
39
40 /// Post a scheduler operation for deferred execution.
41 virtual void post(scheduler_op*) const = 0;
42
43 /// Post a continuation for deferred execution (zero-allocation).
44 virtual void post(capy::continuation&) const = 0;
45
46 /// Increment the outstanding work count.
47 virtual void work_started() noexcept = 0;
48
49 /// Decrement the outstanding work count.
50 virtual void work_finished() noexcept = 0;
51
52 /// Check if the calling thread is running the event loop.
53 virtual bool running_in_this_thread() const noexcept = 0;
54
55 /// Signal the event loop to stop.
56 virtual void stop() = 0;
57
58 /// Check if the event loop has been stopped.
59 virtual bool stopped() const noexcept = 0;
60
61 /// Reset the stopped state so `run()` can be called again.
62 virtual void restart() = 0;
63
64 /// Run the event loop, blocking until all work completes.
65 virtual std::size_t run() = 0;
66
67 /// Run one handler, blocking until one completes.
68 virtual std::size_t run_one() = 0;
69
70 /** Run one handler, blocking up to @p usec microseconds.
71
72 @param usec Maximum wait time in microseconds.
73
74 @return The number of handlers executed (0 or 1).
75 */
76 virtual std::size_t wait_one(long usec) = 0;
77
78 /// Run all ready handlers without blocking.
79 virtual std::size_t poll() = 0;
80
81 /// Run at most one ready handler without blocking.
82 virtual std::size_t poll_one() = 0;
83
84 /** Register the read end of the POSIX signal self-pipe.
85
86 Called once (by the first signal_set to register a signal) so the
87 backend's event loop watches @p read_fd for readability. When the
88 pipe becomes readable the backend drains it and calls
89 `posix_signal_service::deliver_signal` for each pending signal, in
90 normal thread context. This keeps the C signal handler
91 async-signal-safe: it only writes the signal number to the pipe.
92
93 POSIX backends override this; the default is a no-op (Windows/IOCP
94 uses synchronous C-runtime signal handling instead).
95
96 @param read_fd The read end of the global signal self-pipe.
97 */
98 ✗ virtual void register_signal_reader(int read_fd) { (void)read_fd; }
99
100 /// Decomposed threading configuration applied via @ref configure_threading.
101 struct threading_config
102 {
103 /// Scheduler mutex/condvar enabled. Off only in the `unsafe` tier.
104 bool scheduler_locking = true;
105 /// Per-descriptor (reactor) or ring (io_uring) I/O lock enabled.
106 /// Off in the `unsafe_io` and `unsafe` tiers.
107 bool reactor_io_locking = true;
108 /// A single run thread is guaranteed (a lockless tier): elide
109 /// inter-run-thread wakeups.
110 bool one_thread = false;
111 };
112
113 /// True in the fully-lockless (`unsafe`) tier. The resolver and POSIX
114 /// file services gate their `operation_not_supported` result on this.
115 ✗ virtual bool scheduler_locking_disabled() const noexcept { return false; }
116
117 /// Apply @ref threading_config. Default no-op.
118 ✗ virtual void configure_threading(threading_config) noexcept {}
119 };
120
121 } // namespace boost::corosio::detail
122
123 #endif
124