107 lines
2.4 KiB
C++
107 lines
2.4 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#include "SocketEvent.hxx"
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#include "Loop.hxx"
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#include "event/Features.h"
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#include <cassert>
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#include <utility>
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#ifdef USE_EPOLL
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#include <cerrno>
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#endif
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void
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SocketEvent::Open(SocketDescriptor _fd) noexcept
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{
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assert(_fd.IsDefined());
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assert(!fd.IsDefined());
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assert(GetScheduledFlags() == 0);
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fd = _fd;
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}
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void
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SocketEvent::Close() noexcept
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{
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if (!fd.IsDefined())
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return;
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/* closing the socket automatically unregisters it from epoll,
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so we can omit the epoll_ctl(EPOLL_CTL_DEL) call and save
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one system call */
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if (std::exchange(scheduled_flags, 0) != 0) {
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#ifdef HAVE_THREADED_EVENT_LOOP
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/* can't use this optimization in multi-threaded
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programs, because all file descriptors get
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duplicated in forked processes, leaving them
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registered in epoll, which could cause the parent
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to crash */
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loop.RemoveFD(fd.Get(), *this);
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#else
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loop.AbandonFD(*this);
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#endif
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}
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fd.Close();
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}
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void
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SocketEvent::Abandon() noexcept
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{
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if (std::exchange(scheduled_flags, 0) != 0)
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loop.AbandonFD(*this);
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fd = SocketDescriptor::Undefined();
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}
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bool
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SocketEvent::Schedule(unsigned flags) noexcept
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{
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if (flags != 0)
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flags |= IMPLICIT_FLAGS;
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if (flags == GetScheduledFlags())
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return true;
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assert(IsDefined());
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bool success;
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if (scheduled_flags == 0)
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success = loop.AddFD(fd.Get(), flags, *this);
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else if (flags == 0)
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success = loop.RemoveFD(fd.Get(), *this);
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else
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success = loop.ModifyFD(fd.Get(), flags, *this);
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if (success)
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scheduled_flags = flags;
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#ifdef USE_EPOLL
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else if (errno == EBADF || errno == ENOENT)
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/* the socket was probably closed by somebody else
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(EBADF) or a new file descriptor with the same
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number was created but not registered already
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(ENOENT) - we can assume that there are no
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scheduled events */
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/* note that when this happens, we're actually lucky
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that it has failed - imagine another thread may
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meanwhile have created something on the same file
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descriptor number, and has registered it; the
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epoll_ctl() call above would then have succeeded,
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but broke the other thread's epoll registration */
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scheduled_flags = 0;
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#endif
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return success;
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}
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void
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SocketEvent::Dispatch() noexcept
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{
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const unsigned flags = std::exchange(ready_flags, 0) &
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GetScheduledFlags();
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if (flags != 0)
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callback(flags);
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}
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