1   
//
1   
//
2   
// Copyright (c) 2026 Steve Gerbino
2   
// Copyright (c) 2026 Steve Gerbino
3   
//
3   
//
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
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)
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   
//
6   
//
7   
// Official repository: https://github.com/cppalliance/corosio
7   
// Official repository: https://github.com/cppalliance/corosio
8   
//
8   
//
9  
9  
10   
#ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
10   
#ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
11   
#define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
11   
#define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
12  
12  
13   
#include <boost/corosio/detail/platform.hpp>
13   
#include <boost/corosio/detail/platform.hpp>
14  
14  
15   
#if BOOST_COROSIO_HAS_SELECT
15   
#if BOOST_COROSIO_HAS_SELECT
16  
16  
17   
#include <boost/corosio/detail/config.hpp>
17   
#include <boost/corosio/detail/config.hpp>
18   
#include <boost/capy/ex/execution_context.hpp>
18   
#include <boost/capy/ex/execution_context.hpp>
19  
19  
20   
#include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
20   
#include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
21  
21  
22 - 
#include <boost/corosio/native/detail/select/select_op.hpp>
22 + 
#include <boost/corosio/native/detail/select/select_traits.hpp>
23   
#include <boost/corosio/detail/timer_service.hpp>
23   
#include <boost/corosio/detail/timer_service.hpp>
24   
#include <boost/corosio/native/detail/make_err.hpp>
24   
#include <boost/corosio/native/detail/make_err.hpp>
25   
#include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
25   
#include <boost/corosio/native/detail/posix/posix_resolver_service.hpp>
26   
#include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
26   
#include <boost/corosio/native/detail/posix/posix_signal_service.hpp>
27   
#include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
27   
#include <boost/corosio/native/detail/posix/posix_stream_file_service.hpp>
28   
#include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
28   
#include <boost/corosio/native/detail/posix/posix_random_access_file_service.hpp>
29  
29  
30   
#include <boost/corosio/detail/except.hpp>
30   
#include <boost/corosio/detail/except.hpp>
31  
31  
32   
#include <sys/select.h>
32   
#include <sys/select.h>
33   
#include <unistd.h>
33   
#include <unistd.h>
34   
#include <errno.h>
34   
#include <errno.h>
35   
#include <fcntl.h>
35   
#include <fcntl.h>
36  
36  
37   
#include <atomic>
37   
#include <atomic>
38   
#include <chrono>
38   
#include <chrono>
39   
#include <cstdint>
39   
#include <cstdint>
40   
#include <limits>
40   
#include <limits>
41   
#include <mutex>
41   
#include <mutex>
42   
#include <unordered_map>
42   
#include <unordered_map>
43  
43  
44   
namespace boost::corosio::detail {
44   
namespace boost::corosio::detail {
45  
45  
46 - 
struct select_descriptor_state;
 
47   
struct select_op;
46   
struct select_op;
48  
47  
49   
/** POSIX scheduler using select() for I/O multiplexing.
48   
/** POSIX scheduler using select() for I/O multiplexing.
50  
49  
51   
    This scheduler implements the scheduler interface using the POSIX select()
50   
    This scheduler implements the scheduler interface using the POSIX select()
52   
    call for I/O event notification. It inherits the shared reactor threading
51   
    call for I/O event notification. It inherits the shared reactor threading
53   
    model from reactor_scheduler: signal state machine, inline completion
52   
    model from reactor_scheduler: signal state machine, inline completion
54   
    budget, work counting, and the do_one event loop.
53   
    budget, work counting, and the do_one event loop.
55  
54  
56   
    The design mirrors epoll_scheduler for behavioral consistency:
55   
    The design mirrors epoll_scheduler for behavioral consistency:
57   
    - Same single-reactor thread coordination model
56   
    - Same single-reactor thread coordination model
58   
    - Same deferred I/O pattern (reactor marks ready; workers do I/O)
57   
    - Same deferred I/O pattern (reactor marks ready; workers do I/O)
59   
    - Same timer integration pattern
58   
    - Same timer integration pattern
60  
59  
61   
    Known Limitations:
60   
    Known Limitations:
62   
    - FD_SETSIZE (~1024) limits maximum concurrent connections
61   
    - FD_SETSIZE (~1024) limits maximum concurrent connections
63   
    - O(n) scanning: rebuilds fd_sets each iteration
62   
    - O(n) scanning: rebuilds fd_sets each iteration
64   
    - Level-triggered only (no edge-triggered mode)
63   
    - Level-triggered only (no edge-triggered mode)
65  
64  
66   
    @par Thread Safety
65   
    @par Thread Safety
67   
    All public member functions are thread-safe.
66   
    All public member functions are thread-safe.
68   
*/
67   
*/
69   
class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
68   
class BOOST_COROSIO_DECL select_scheduler final : public reactor_scheduler
70   
{
69   
{
71   
public:
70   
public:
72   
    /** Construct the scheduler.
71   
    /** Construct the scheduler.
73  
72  
74   
        Creates a self-pipe for reactor interruption.
73   
        Creates a self-pipe for reactor interruption.
75  
74  
76   
        @param ctx Reference to the owning execution_context.
75   
        @param ctx Reference to the owning execution_context.
77   
        @param concurrency_hint Hint for expected thread count (unused).
76   
        @param concurrency_hint Hint for expected thread count (unused).
78   
    */
77   
    */
79   
    select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
78   
    select_scheduler(capy::execution_context& ctx, int concurrency_hint = -1);
80  
79  
81   
    /// Destroy the scheduler.
80   
    /// Destroy the scheduler.
82   
    ~select_scheduler() override;
81   
    ~select_scheduler() override;
83  
82  
84   
    select_scheduler(select_scheduler const&)            = delete;
83   
    select_scheduler(select_scheduler const&)            = delete;
85   
    select_scheduler& operator=(select_scheduler const&) = delete;
84   
    select_scheduler& operator=(select_scheduler const&) = delete;
86  
85  
87   
    /// Shut down the scheduler, draining pending operations.
86   
    /// Shut down the scheduler, draining pending operations.
88   
    void shutdown() override;
87   
    void shutdown() override;
89  
88  
90   
    /** Return the maximum file descriptor value supported.
89   
    /** Return the maximum file descriptor value supported.
91  
90  
92   
        Returns FD_SETSIZE - 1, the maximum fd value that can be
91   
        Returns FD_SETSIZE - 1, the maximum fd value that can be
93   
        monitored by select(). Operations with fd >= FD_SETSIZE
92   
        monitored by select(). Operations with fd >= FD_SETSIZE
94   
        will fail with EINVAL.
93   
        will fail with EINVAL.
95  
94  
96   
        @return The maximum supported file descriptor value.
95   
        @return The maximum supported file descriptor value.
97   
    */
96   
    */
98   
    static constexpr int max_fd() noexcept
97   
    static constexpr int max_fd() noexcept
99   
    {
98   
    {
100   
        return FD_SETSIZE - 1;
99   
        return FD_SETSIZE - 1;
101   
    }
100   
    }
102  
101  
103   
    /** Register a descriptor for persistent monitoring.
102   
    /** Register a descriptor for persistent monitoring.
104  
103  
105   
        The fd is added to the registered_descs_ map and will be
104   
        The fd is added to the registered_descs_ map and will be
106   
        included in subsequent select() calls. The reactor is
105   
        included in subsequent select() calls. The reactor is
107   
        interrupted so a blocked select() rebuilds its fd_sets.
106   
        interrupted so a blocked select() rebuilds its fd_sets.
108  
107  
109   
        @param fd The file descriptor to register.
108   
        @param fd The file descriptor to register.
110   
        @param desc Pointer to descriptor state for this fd.
109   
        @param desc Pointer to descriptor state for this fd.
111   
    */
110   
    */
112 - 
    void register_descriptor(int fd, select_descriptor_state* desc) const;
111 + 
    void register_descriptor(int fd, reactor_descriptor_state* desc) const;
113  
112  
114   
    /** Deregister a persistently registered descriptor.
113   
    /** Deregister a persistently registered descriptor.
115  
114  
116   
        @param fd The file descriptor to deregister.
115   
        @param fd The file descriptor to deregister.
117   
    */
116   
    */
118   
    void deregister_descriptor(int fd) const;
117   
    void deregister_descriptor(int fd) const;
119  
118  
120   
    /** Interrupt the reactor so it rebuilds its fd_sets.
119   
    /** Interrupt the reactor so it rebuilds its fd_sets.
121  
120  
122   
        Called when a write or connect op is registered after
121   
        Called when a write or connect op is registered after
123   
        the reactor's snapshot was taken. Without this, select()
122   
        the reactor's snapshot was taken. Without this, select()
124   
        may block not watching for writability on the fd.
123   
        may block not watching for writability on the fd.
125   
    */
124   
    */
126   
    void notify_reactor() const;
125   
    void notify_reactor() const;
127  
126  
128   
private:
127   
private:
129   
    void
128   
    void
130   
    run_task(lock_type& lock, context_type* ctx,
129   
    run_task(lock_type& lock, context_type* ctx,
131   
        long timeout_us) override;
130   
        long timeout_us) override;
132   
    void interrupt_reactor() const override;
131   
    void interrupt_reactor() const override;
133   
    long calculate_timeout(long requested_timeout_us) const;
132   
    long calculate_timeout(long requested_timeout_us) const;
134  
133  
135   
    // Self-pipe for interrupting select()
134   
    // Self-pipe for interrupting select()
136   
    int pipe_fds_[2]; // [0]=read, [1]=write
135   
    int pipe_fds_[2]; // [0]=read, [1]=write
137  
136  
138   
    // Per-fd tracking for fd_set building
137   
    // Per-fd tracking for fd_set building
139 - 
    mutable std::unordered_map<int, select_descriptor_state*> registered_descs_;
138 + 
    mutable std::unordered_map<int, reactor_descriptor_state*> registered_descs_;
140   
    mutable int max_fd_ = -1;
139   
    mutable int max_fd_ = -1;
141   
};
140   
};
142  
141  
143   
inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
142   
inline select_scheduler::select_scheduler(capy::execution_context& ctx, int)
144   
    : pipe_fds_{-1, -1}
143   
    : pipe_fds_{-1, -1}
145   
    , max_fd_(-1)
144   
    , max_fd_(-1)
146   
{
145   
{
147   
    if (::pipe(pipe_fds_) < 0)
146   
    if (::pipe(pipe_fds_) < 0)
148   
        detail::throw_system_error(make_err(errno), "pipe");
147   
        detail::throw_system_error(make_err(errno), "pipe");
149  
148  
150   
    for (int i = 0; i < 2; ++i)
149   
    for (int i = 0; i < 2; ++i)
151   
    {
150   
    {
152   
        int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
151   
        int flags = ::fcntl(pipe_fds_[i], F_GETFL, 0);
153   
        if (flags == -1)
152   
        if (flags == -1)
154   
        {
153   
        {
155   
            int errn = errno;
154   
            int errn = errno;
156   
            ::close(pipe_fds_[0]);
155   
            ::close(pipe_fds_[0]);
157   
            ::close(pipe_fds_[1]);
156   
            ::close(pipe_fds_[1]);
158   
            detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
157   
            detail::throw_system_error(make_err(errn), "fcntl F_GETFL");
159   
        }
158   
        }
160   
        if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
159   
        if (::fcntl(pipe_fds_[i], F_SETFL, flags | O_NONBLOCK) == -1)
161   
        {
160   
        {
162   
            int errn = errno;
161   
            int errn = errno;
163   
            ::close(pipe_fds_[0]);
162   
            ::close(pipe_fds_[0]);
164   
            ::close(pipe_fds_[1]);
163   
            ::close(pipe_fds_[1]);
165   
            detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
164   
            detail::throw_system_error(make_err(errn), "fcntl F_SETFL");
166   
        }
165   
        }
167   
        if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
166   
        if (::fcntl(pipe_fds_[i], F_SETFD, FD_CLOEXEC) == -1)
168   
        {
167   
        {
169   
            int errn = errno;
168   
            int errn = errno;
170   
            ::close(pipe_fds_[0]);
169   
            ::close(pipe_fds_[0]);
171   
            ::close(pipe_fds_[1]);
170   
            ::close(pipe_fds_[1]);
172   
            detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
171   
            detail::throw_system_error(make_err(errn), "fcntl F_SETFD");
173   
        }
172   
        }
174   
    }
173   
    }
175  
174  
176   
    timer_svc_ = &get_timer_service(ctx, *this);
175   
    timer_svc_ = &get_timer_service(ctx, *this);
177   
    timer_svc_->set_on_earliest_changed(
176   
    timer_svc_->set_on_earliest_changed(
178   
        timer_service::callback(this, [](void* p) {
177   
        timer_service::callback(this, [](void* p) {
179   
            static_cast<select_scheduler*>(p)->interrupt_reactor();
178   
            static_cast<select_scheduler*>(p)->interrupt_reactor();
180   
        }));
179   
        }));
181  
180  
182   
    get_resolver_service(ctx, *this);
181   
    get_resolver_service(ctx, *this);
183   
    get_signal_service(ctx, *this);
182   
    get_signal_service(ctx, *this);
184   
    get_stream_file_service(ctx, *this);
183   
    get_stream_file_service(ctx, *this);
185   
    get_random_access_file_service(ctx, *this);
184   
    get_random_access_file_service(ctx, *this);
186  
185  
187   
    completed_ops_.push(&task_op_);
186   
    completed_ops_.push(&task_op_);
188   
}
187   
}
189  
188  
190   
inline select_scheduler::~select_scheduler()
189   
inline select_scheduler::~select_scheduler()
191   
{
190   
{
192   
    if (pipe_fds_[0] >= 0)
191   
    if (pipe_fds_[0] >= 0)
193   
        ::close(pipe_fds_[0]);
192   
        ::close(pipe_fds_[0]);
194   
    if (pipe_fds_[1] >= 0)
193   
    if (pipe_fds_[1] >= 0)
195   
        ::close(pipe_fds_[1]);
194   
        ::close(pipe_fds_[1]);
196   
}
195   
}
197  
196  
198   
inline void
197   
inline void
199   
select_scheduler::shutdown()
198   
select_scheduler::shutdown()
200   
{
199   
{
201   
    shutdown_drain();
200   
    shutdown_drain();
202  
201  
203   
    if (pipe_fds_[1] >= 0)
202   
    if (pipe_fds_[1] >= 0)
204   
        interrupt_reactor();
203   
        interrupt_reactor();
205   
}
204   
}
206  
205  
207   
inline void
206   
inline void
208   
select_scheduler::register_descriptor(
207   
select_scheduler::register_descriptor(
209 - 
    int fd, select_descriptor_state* desc) const
208 + 
    int fd, reactor_descriptor_state* desc) const
210   
{
209   
{
211   
    if (fd < 0 || fd >= FD_SETSIZE)
210   
    if (fd < 0 || fd >= FD_SETSIZE)
212   
        detail::throw_system_error(make_err(EINVAL), "select: fd out of range");
211   
        detail::throw_system_error(make_err(EINVAL), "select: fd out of range");
213  
212  
214   
    desc->registered_events = reactor_event_read | reactor_event_write;
213   
    desc->registered_events = reactor_event_read | reactor_event_write;
215   
    desc->fd                = fd;
214   
    desc->fd                = fd;
216   
    desc->scheduler_        = this;
215   
    desc->scheduler_        = this;
217   
    desc->mutex.set_enabled(!single_threaded_);
216   
    desc->mutex.set_enabled(!single_threaded_);
218   
    desc->ready_events_.store(0, std::memory_order_relaxed);
217   
    desc->ready_events_.store(0, std::memory_order_relaxed);
219  
218  
220   
    {
219   
    {
221   
        conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
220   
        conditionally_enabled_mutex::scoped_lock lock(desc->mutex);
222   
        desc->impl_ref_.reset();
221   
        desc->impl_ref_.reset();
223   
        desc->read_ready  = false;
222   
        desc->read_ready  = false;
224   
        desc->write_ready = false;
223   
        desc->write_ready = false;
225   
    }
224   
    }
226  
225  
227   
    {
226   
    {
228   
        mutex_type::scoped_lock lock(mutex_);
227   
        mutex_type::scoped_lock lock(mutex_);
229   
        registered_descs_[fd] = desc;
228   
        registered_descs_[fd] = desc;
230   
        if (fd > max_fd_)
229   
        if (fd > max_fd_)
231   
            max_fd_ = fd;
230   
            max_fd_ = fd;
232   
    }
231   
    }
233  
232  
234   
    interrupt_reactor();
233   
    interrupt_reactor();
235   
}
234   
}
236  
235  
237   
inline void
236   
inline void
238   
select_scheduler::deregister_descriptor(int fd) const
237   
select_scheduler::deregister_descriptor(int fd) const
239   
{
238   
{
240   
    mutex_type::scoped_lock lock(mutex_);
239   
    mutex_type::scoped_lock lock(mutex_);
241  
240  
242   
    auto it = registered_descs_.find(fd);
241   
    auto it = registered_descs_.find(fd);
243   
    if (it == registered_descs_.end())
242   
    if (it == registered_descs_.end())
244   
        return;
243   
        return;
245  
244  
246   
    registered_descs_.erase(it);
245   
    registered_descs_.erase(it);
247  
246  
248   
    if (fd == max_fd_)
247   
    if (fd == max_fd_)
249   
    {
248   
    {
250   
        max_fd_ = pipe_fds_[0];
249   
        max_fd_ = pipe_fds_[0];
251   
        for (auto& [registered_fd, state] : registered_descs_)
250   
        for (auto& [registered_fd, state] : registered_descs_)
252   
        {
251   
        {
253   
            if (registered_fd > max_fd_)
252   
            if (registered_fd > max_fd_)
254   
                max_fd_ = registered_fd;
253   
                max_fd_ = registered_fd;
255   
        }
254   
        }
256   
    }
255   
    }
257   
}
256   
}
258  
257  
259   
inline void
258   
inline void
260   
select_scheduler::notify_reactor() const
259   
select_scheduler::notify_reactor() const
261   
{
260   
{
262   
    interrupt_reactor();
261   
    interrupt_reactor();
263   
}
262   
}
264  
263  
265   
inline void
264   
inline void
266   
select_scheduler::interrupt_reactor() const
265   
select_scheduler::interrupt_reactor() const
267   
{
266   
{
268   
    char byte               = 1;
267   
    char byte               = 1;
269   
    [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
268   
    [[maybe_unused]] auto r = ::write(pipe_fds_[1], &byte, 1);
270   
}
269   
}
271  
270  
272   
inline long
271   
inline long
273   
select_scheduler::calculate_timeout(long requested_timeout_us) const
272   
select_scheduler::calculate_timeout(long requested_timeout_us) const
274   
{
273   
{
275   
    if (requested_timeout_us == 0)
274   
    if (requested_timeout_us == 0)
276   
        return 0;
275   
        return 0;
277  
276  
278   
    auto nearest = timer_svc_->nearest_expiry();
277   
    auto nearest = timer_svc_->nearest_expiry();
279   
    if (nearest == timer_service::time_point::max())
278   
    if (nearest == timer_service::time_point::max())
280   
        return requested_timeout_us;
279   
        return requested_timeout_us;
281  
280  
282   
    auto now = std::chrono::steady_clock::now();
281   
    auto now = std::chrono::steady_clock::now();
283   
    if (nearest <= now)
282   
    if (nearest <= now)
284   
        return 0;
283   
        return 0;
285  
284  
286   
    auto timer_timeout_us =
285   
    auto timer_timeout_us =
287   
        std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
286   
        std::chrono::duration_cast<std::chrono::microseconds>(nearest - now)
288   
            .count();
287   
            .count();
289  
288  
290   
    constexpr auto long_max =
289   
    constexpr auto long_max =
291   
        static_cast<long long>((std::numeric_limits<long>::max)());
290   
        static_cast<long long>((std::numeric_limits<long>::max)());
292   
    auto capped_timer_us =
291   
    auto capped_timer_us =
293   
        (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
292   
        (std::min)((std::max)(static_cast<long long>(timer_timeout_us),
294   
                              static_cast<long long>(0)),
293   
                              static_cast<long long>(0)),
295   
                   long_max);
294   
                   long_max);
296  
295  
297   
    if (requested_timeout_us < 0)
296   
    if (requested_timeout_us < 0)
298   
        return static_cast<long>(capped_timer_us);
297   
        return static_cast<long>(capped_timer_us);
299  
298  
300   
    return static_cast<long>(
299   
    return static_cast<long>(
301   
        (std::min)(static_cast<long long>(requested_timeout_us),
300   
        (std::min)(static_cast<long long>(requested_timeout_us),
302   
                   capped_timer_us));
301   
                   capped_timer_us));
303   
}
302   
}
304  
303  
305   
inline void
304   
inline void
306   
select_scheduler::run_task(
305   
select_scheduler::run_task(
307   
    lock_type& lock, context_type* ctx, long timeout_us)
306   
    lock_type& lock, context_type* ctx, long timeout_us)
308   
{
307   
{
309   
    long effective_timeout_us =
308   
    long effective_timeout_us =
310   
        task_interrupted_ ? 0 : calculate_timeout(timeout_us);
309   
        task_interrupted_ ? 0 : calculate_timeout(timeout_us);
311  
310  
312   
    // Snapshot registered descriptors while holding lock.
311   
    // Snapshot registered descriptors while holding lock.
313   
    // Record which fds need write monitoring to avoid a hot loop:
312   
    // Record which fds need write monitoring to avoid a hot loop:
314   
    // select is level-triggered so writable sockets (nearly always
313   
    // select is level-triggered so writable sockets (nearly always
315   
    // writable) would cause select() to return immediately every
314   
    // writable) would cause select() to return immediately every
316   
    // iteration if unconditionally added to write_fds.
315   
    // iteration if unconditionally added to write_fds.
317   
    struct fd_entry
316   
    struct fd_entry
318   
    {
317   
    {
319   
        int fd;
318   
        int fd;
320 - 
        select_descriptor_state* desc;
319 + 
        reactor_descriptor_state* desc;
321   
        bool needs_write;
320   
        bool needs_write;
322   
    };
321   
    };
323   
    fd_entry snapshot[FD_SETSIZE];
322   
    fd_entry snapshot[FD_SETSIZE];
324   
    int snapshot_count = 0;
323   
    int snapshot_count = 0;
325  
324  
326   
    for (auto& [fd, desc] : registered_descs_)
325   
    for (auto& [fd, desc] : registered_descs_)
327   
    {
326   
    {
328   
        if (snapshot_count < FD_SETSIZE)
327   
        if (snapshot_count < FD_SETSIZE)
329   
        {
328   
        {
330   
            conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
329   
            conditionally_enabled_mutex::scoped_lock desc_lock(desc->mutex);
331   
            snapshot[snapshot_count].fd   = fd;
330   
            snapshot[snapshot_count].fd   = fd;
332   
            snapshot[snapshot_count].desc = desc;
331   
            snapshot[snapshot_count].desc = desc;
333   
            snapshot[snapshot_count].needs_write =
332   
            snapshot[snapshot_count].needs_write =
334   
                (desc->write_op || desc->connect_op);
333   
                (desc->write_op || desc->connect_op);
335   
            ++snapshot_count;
334   
            ++snapshot_count;
336   
        }
335   
        }
337   
    }
336   
    }
338  
337  
339   
    if (lock.owns_lock())
338   
    if (lock.owns_lock())
340   
        lock.unlock();
339   
        lock.unlock();
341  
340  
342   
    task_cleanup on_exit{this, &lock, ctx};
341   
    task_cleanup on_exit{this, &lock, ctx};
343  
342  
344   
    fd_set read_fds, write_fds, except_fds;
343   
    fd_set read_fds, write_fds, except_fds;
345   
    FD_ZERO(&read_fds);
344   
    FD_ZERO(&read_fds);
346   
    FD_ZERO(&write_fds);
345   
    FD_ZERO(&write_fds);
347   
    FD_ZERO(&except_fds);
346   
    FD_ZERO(&except_fds);
348  
347  
349   
    FD_SET(pipe_fds_[0], &read_fds);
348   
    FD_SET(pipe_fds_[0], &read_fds);
350   
    int nfds = pipe_fds_[0];
349   
    int nfds = pipe_fds_[0];
351  
350  
352   
    for (int i = 0; i < snapshot_count; ++i)
351   
    for (int i = 0; i < snapshot_count; ++i)
353   
    {
352   
    {
354   
        int fd = snapshot[i].fd;
353   
        int fd = snapshot[i].fd;
355   
        FD_SET(fd, &read_fds);
354   
        FD_SET(fd, &read_fds);
356   
        if (snapshot[i].needs_write)
355   
        if (snapshot[i].needs_write)
357   
            FD_SET(fd, &write_fds);
356   
            FD_SET(fd, &write_fds);
358   
        FD_SET(fd, &except_fds);
357   
        FD_SET(fd, &except_fds);
359   
        if (fd > nfds)
358   
        if (fd > nfds)
360   
            nfds = fd;
359   
            nfds = fd;
361   
    }
360   
    }
362  
361  
363   
    struct timeval tv;
362   
    struct timeval tv;
364   
    struct timeval* tv_ptr = nullptr;
363   
    struct timeval* tv_ptr = nullptr;
365   
    if (effective_timeout_us >= 0)
364   
    if (effective_timeout_us >= 0)
366   
    {
365   
    {
367   
        tv.tv_sec  = effective_timeout_us / 1000000;
366   
        tv.tv_sec  = effective_timeout_us / 1000000;
368   
        tv.tv_usec = effective_timeout_us % 1000000;
367   
        tv.tv_usec = effective_timeout_us % 1000000;
369   
        tv_ptr     = &tv;
368   
        tv_ptr     = &tv;
370   
    }
369   
    }
371  
370  
372   
    int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr);
371   
    int ready = ::select(nfds + 1, &read_fds, &write_fds, &except_fds, tv_ptr);
373  
372  
374   
    // EINTR: signal interrupted select(), just retry.
373   
    // EINTR: signal interrupted select(), just retry.
375   
    // EBADF: an fd was closed between snapshot and select(); retry
374   
    // EBADF: an fd was closed between snapshot and select(); retry
376   
    // with a fresh snapshot from registered_descs_.
375   
    // with a fresh snapshot from registered_descs_.
377   
    if (ready < 0)
376   
    if (ready < 0)
378   
    {
377   
    {
379   
        if (errno == EINTR || errno == EBADF)
378   
        if (errno == EINTR || errno == EBADF)
380   
            return;
379   
            return;
381   
        detail::throw_system_error(make_err(errno), "select");
380   
        detail::throw_system_error(make_err(errno), "select");
382   
    }
381   
    }
383  
382  
384   
    // Process timers outside the lock
383   
    // Process timers outside the lock
385   
    timer_svc_->process_expired();
384   
    timer_svc_->process_expired();
386  
385  
387   
    op_queue local_ops;
386   
    op_queue local_ops;
388  
387  
389   
    if (ready > 0)
388   
    if (ready > 0)
390   
    {
389   
    {
391   
        if (FD_ISSET(pipe_fds_[0], &read_fds))
390   
        if (FD_ISSET(pipe_fds_[0], &read_fds))
392   
        {
391   
        {
393   
            char buf[256];
392   
            char buf[256];
394   
            while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
393   
            while (::read(pipe_fds_[0], buf, sizeof(buf)) > 0)
395   
            {
394   
            {
396   
            }
395   
            }
397   
        }
396   
        }
398  
397  
399   
        for (int i = 0; i < snapshot_count; ++i)
398   
        for (int i = 0; i < snapshot_count; ++i)
400   
        {
399   
        {
401   
            int fd                        = snapshot[i].fd;
400   
            int fd                        = snapshot[i].fd;
402 - 
            select_descriptor_state* desc = snapshot[i].desc;
401 + 
            reactor_descriptor_state* desc = snapshot[i].desc;
403  
402  
404   
            std::uint32_t flags = 0;
403   
            std::uint32_t flags = 0;
405   
            if (FD_ISSET(fd, &read_fds))
404   
            if (FD_ISSET(fd, &read_fds))
406   
                flags |= reactor_event_read;
405   
                flags |= reactor_event_read;
407   
            if (FD_ISSET(fd, &write_fds))
406   
            if (FD_ISSET(fd, &write_fds))
408   
                flags |= reactor_event_write;
407   
                flags |= reactor_event_write;
409   
            if (FD_ISSET(fd, &except_fds))
408   
            if (FD_ISSET(fd, &except_fds))
410   
                flags |= reactor_event_error;
409   
                flags |= reactor_event_error;
411  
410  
412   
            if (flags == 0)
411   
            if (flags == 0)
413   
                continue;
412   
                continue;
414  
413  
415   
            desc->add_ready_events(flags);
414   
            desc->add_ready_events(flags);
416  
415  
417   
            bool expected = false;
416   
            bool expected = false;
418   
            if (desc->is_enqueued_.compare_exchange_strong(
417   
            if (desc->is_enqueued_.compare_exchange_strong(
419   
                    expected, true, std::memory_order_release,
418   
                    expected, true, std::memory_order_release,
420   
                    std::memory_order_relaxed))
419   
                    std::memory_order_relaxed))
421   
            {
420   
            {
422   
                local_ops.push(desc);
421   
                local_ops.push(desc);
423   
            }
422   
            }
424   
        }
423   
        }
425   
    }
424   
    }
426  
425  
427   
    lock.lock();
426   
    lock.lock();
428  
427  
429   
    if (!local_ops.empty())
428   
    if (!local_ops.empty())
430   
        completed_ops_.splice(local_ops);
429   
        completed_ops_.splice(local_ops);
431   
}
430   
}
432  
431  
433   
} // namespace boost::corosio::detail
432   
} // namespace boost::corosio::detail
434  
433  
435   
#endif // BOOST_COROSIO_HAS_SELECT
434   
#endif // BOOST_COROSIO_HAS_SELECT
436  
435  
437   
#endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP
436   
#endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SCHEDULER_HPP