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//
 
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// Copyright (c) 2026 Steve Gerbino
 
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//
 
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
 
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
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//
 
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// Official repository: https://github.com/cppalliance/corosio
 
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//
 
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#ifndef BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SOCKET_SERVICE_HPP
 
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#define BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SOCKET_SERVICE_HPP
 
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#include <boost/corosio/detail/platform.hpp>
 
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#if BOOST_COROSIO_HAS_SELECT
 
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#include <boost/corosio/detail/config.hpp>
 
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#include <boost/capy/ex/execution_context.hpp>
 
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#include <boost/corosio/detail/socket_service.hpp>
 
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#include <boost/corosio/native/detail/select/select_socket.hpp>
 
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#include <boost/corosio/native/detail/select/select_scheduler.hpp>
 
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#include <boost/corosio/native/detail/reactor/reactor_service_state.hpp>
 
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#include <boost/corosio/native/detail/reactor/reactor_op_complete.hpp>
 
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#include <coroutine>
 
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#include <mutex>
 
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#include <utility>
 
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#include <errno.h>
 
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#include <fcntl.h>
 
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#include <netinet/in.h>
 
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#include <netinet/tcp.h>
 
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#include <sys/select.h>
 
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#include <sys/socket.h>
 
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#include <unistd.h>
 
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/*
 
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    Each I/O op tries the syscall speculatively; only registers with
 
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    the reactor on EAGAIN. Fd is registered once at open time and
 
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    stays registered until close. The reactor only marks ready_events_;
 
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    actual I/O happens in invoke_deferred_io(). cancel() captures
 
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    shared_from_this() into op.impl_ptr to keep the impl alive.
 
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*/
 
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namespace boost::corosio::detail {
 
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/// State for select socket service.
 
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using select_socket_state =
 
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    reactor_service_state<select_scheduler, select_socket>;
 
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/** select socket service implementation.
 
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    Inherits from socket_service to enable runtime polymorphism.
 
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    Uses key_type = socket_service for service lookup.
 
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*/
 
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class BOOST_COROSIO_DECL select_socket_service final : public socket_service
 
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{
 
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public:
 
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    explicit select_socket_service(capy::execution_context& ctx);
 
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    ~select_socket_service() override;
 
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    select_socket_service(select_socket_service const&)            = delete;
 
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    select_socket_service& operator=(select_socket_service const&) = delete;
 
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    void shutdown() override;
 
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    io_object::implementation* construct() override;
 
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    void destroy(io_object::implementation*) override;
 
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    void close(io_object::handle&) override;
 
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    std::error_code open_socket(
 
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        tcp_socket::implementation& impl,
 
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        int family,
 
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        int type,
 
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        int protocol) override;
 
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    select_scheduler& scheduler() const noexcept
 
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    {
 
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        return state_->sched_;
 
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    }
 
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    void post(scheduler_op* op);
 
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    void work_started() noexcept;
 
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    void work_finished() noexcept;
 
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private:
 
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    std::unique_ptr<select_socket_state> state_;
 
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};
 
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inline void
 
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select_connect_op::cancel() noexcept
 
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{
 
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    if (socket_impl_)
 
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        socket_impl_->cancel_single_op(*this);
 
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    else
 
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        request_cancel();
 
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}
 
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inline void
 
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select_read_op::cancel() noexcept
 
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{
 
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    if (socket_impl_)
 
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        socket_impl_->cancel_single_op(*this);
 
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    else
 
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        request_cancel();
 
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}
 
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inline void
 
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select_write_op::cancel() noexcept
 
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{
 
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    if (socket_impl_)
 
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        socket_impl_->cancel_single_op(*this);
 
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    else
 
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        request_cancel();
 
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}
 
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inline void
 
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select_op::operator()()
 
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{
 
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    complete_io_op(*this);
 
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}
 
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inline void
 
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select_connect_op::operator()()
 
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{
 
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    complete_connect_op(*this);
 
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}
 
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inline select_socket::select_socket(select_socket_service& svc) noexcept
 
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    : reactor_socket(svc)
 
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{
 
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}
 
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inline select_socket::~select_socket() = default;
 
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inline std::coroutine_handle<>
 
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select_socket::connect(
 
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    std::coroutine_handle<> h,
 
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    capy::executor_ref ex,
 
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    endpoint ep,
 
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    std::stop_token token,
 
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    std::error_code* ec)
 
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{
 
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    auto result = do_connect(h, ex, ep, token, ec);
 
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    // Rebuild fd_sets so select() watches for writability
 
146 - 
    if (result == std::noop_coroutine())
 
147 - 
        svc_.scheduler().notify_reactor();
 
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    return result;
 
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}
 
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inline std::coroutine_handle<>
 
152 - 
select_socket::read_some(
 
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    std::coroutine_handle<> h,
 
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    capy::executor_ref ex,
 
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    buffer_param param,
 
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    std::stop_token token,
 
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    std::error_code* ec,
 
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    std::size_t* bytes_out)
 
159 - 
{
 
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    return do_read_some(h, ex, param, token, ec, bytes_out);
 
161 - 
}
 
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163 - 
inline std::coroutine_handle<>
 
164 - 
select_socket::write_some(
 
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    std::coroutine_handle<> h,
 
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    capy::executor_ref ex,
 
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    buffer_param param,
 
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    std::stop_token token,
 
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    std::error_code* ec,
 
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    std::size_t* bytes_out)
 
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{
 
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    auto result = do_write_some(h, ex, param, token, ec, bytes_out);
 
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    // Rebuild fd_sets so select() watches for writability
 
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    if (result == std::noop_coroutine())
 
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        svc_.scheduler().notify_reactor();
 
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    return result;
 
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}
 
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inline void
 
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select_socket::cancel() noexcept
 
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{
 
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    do_cancel();
 
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}
 
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inline void
 
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select_socket::close_socket() noexcept
 
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{
 
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    do_close_socket();
 
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}
 
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inline select_socket_service::select_socket_service(
 
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    capy::execution_context& ctx)
 
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    : state_(
 
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          std::make_unique<select_socket_state>(
 
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              ctx.use_service<select_scheduler>()))
 
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{
 
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}
 
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inline select_socket_service::~select_socket_service() {}
 
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inline void
 
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select_socket_service::shutdown()
 
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{
 
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    std::lock_guard lock(state_->mutex_);
 
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    while (auto* impl = state_->impl_list_.pop_front())
 
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        impl->close_socket();
 
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    // Don't clear impl_ptrs_ here. The scheduler shuts down after us and
 
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    // drains completed_ops_, calling destroy() on each queued op. Letting
 
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    // ~state_ release the ptrs (during service destruction, after scheduler
 
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    // shutdown) keeps every impl alive until all ops have been drained.
 
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}
 
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inline io_object::implementation*
 
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select_socket_service::construct()
 
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{
 
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    auto impl = std::make_shared<select_socket>(*this);
 
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    auto* raw = impl.get();
 
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    {
 
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        std::lock_guard lock(state_->mutex_);
 
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        state_->impl_ptrs_.emplace(raw, std::move(impl));
 
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        state_->impl_list_.push_back(raw);
 
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    }
 
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    return raw;
 
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}
 
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inline void
 
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select_socket_service::destroy(io_object::implementation* impl)
 
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{
 
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    auto* select_impl = static_cast<select_socket*>(impl);
 
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    select_impl->close_socket();
 
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    std::lock_guard lock(state_->mutex_);
 
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    state_->impl_list_.remove(select_impl);
 
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    state_->impl_ptrs_.erase(select_impl);
 
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}
 
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inline std::error_code
 
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select_socket_service::open_socket(
 
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    tcp_socket::implementation& impl, int family, int type, int protocol)
 
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{
 
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    auto* select_impl = static_cast<select_socket*>(&impl);
 
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    select_impl->close_socket();
 
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    int fd = ::socket(family, type, protocol);
 
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    if (fd < 0)
 
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        return make_err(errno);
 
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    if (family == AF_INET6)
 
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    {
 
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        int one = 1;
 
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        ::setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 
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    }
 
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    int flags = ::fcntl(fd, F_GETFL, 0);
 
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    if (flags == -1)
 
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    {
 
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        int errn = errno;
 
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        ::close(fd);
 
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        return make_err(errn);
 
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    }
 
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    if (::fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1)
 
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    {
 
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        int errn = errno;
 
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        ::close(fd);
 
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        return make_err(errn);
 
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    }
 
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    if (::fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
 
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    {
 
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        int errn = errno;
 
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        ::close(fd);
 
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        return make_err(errn);
 
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    }
 
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    if (fd >= FD_SETSIZE)
 
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    {
 
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        ::close(fd);
 
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        return make_err(EMFILE);
 
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    }
 
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#ifdef SO_NOSIGPIPE
 
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    {
 
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        int one = 1;
 
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        ::setsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE, &one, sizeof(one));
 
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    }
 
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#endif
 
289 -
 
290 - 
    select_impl->fd_ = fd;
 
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292 - 
    select_impl->desc_state_.fd = fd;
 
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    {
 
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        std::lock_guard lock(select_impl->desc_state_.mutex);
 
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        select_impl->desc_state_.read_op    = nullptr;
 
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        select_impl->desc_state_.write_op   = nullptr;
 
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        select_impl->desc_state_.connect_op = nullptr;
 
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    }
 
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    scheduler().register_descriptor(fd, &select_impl->desc_state_);
 
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    return {};
 
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}
 
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304 - 
inline void
 
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select_socket_service::close(io_object::handle& h)
 
306 - 
{
 
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    static_cast<select_socket*>(h.get())->close_socket();
 
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}
 
309 -
 
310 - 
inline void
 
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select_socket_service::post(scheduler_op* op)
 
312 - 
{
 
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    state_->sched_.post(op);
 
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}
 
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316 - 
inline void
 
317 - 
select_socket_service::work_started() noexcept
 
318 - 
{
 
319 - 
    state_->sched_.work_started();
 
320 - 
}
 
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322 - 
inline void
 
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select_socket_service::work_finished() noexcept
 
324 - 
{
 
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    state_->sched_.work_finished();
 
326 - 
}
 
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} // namespace boost::corosio::detail
 
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#endif // BOOST_COROSIO_HAS_SELECT
 
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#endif // BOOST_COROSIO_NATIVE_DETAIL_SELECT_SELECT_SOCKET_SERVICE_HPP