127 lines
3.5 KiB
C++
127 lines
3.5 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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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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#include "td/utils/port/detail/EventFdLinux.h"
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char disable_linker_warning_about_empty_file_event_fd_linux_cpp TD_UNUSED;
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#ifdef TD_EVENTFD_LINUX
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#include "td/utils/logging.h"
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#include "td/utils/misc.h"
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#include "td/utils/port/detail/NativeFd.h"
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#include "td/utils/port/PollFlags.h"
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#include "td/utils/ScopeGuard.h"
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#include "td/utils/Slice.h"
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#include <poll.h>
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#include <sys/eventfd.h>
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#include <unistd.h>
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namespace td {
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namespace detail {
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class EventFdLinuxImpl {
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public:
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PollableFdInfo info;
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};
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EventFdLinux::EventFdLinux() = default;
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EventFdLinux::EventFdLinux(EventFdLinux &&) = default;
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EventFdLinux &EventFdLinux::operator=(EventFdLinux &&) = default;
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EventFdLinux::~EventFdLinux() = default;
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void EventFdLinux::init() {
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auto fd = NativeFd(eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC));
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auto eventfd_errno = errno;
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LOG_IF(FATAL, !fd) << Status::PosixError(eventfd_errno, "eventfd call failed");
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impl_ = make_unique<EventFdLinuxImpl>();
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impl_->info.set_native_fd(std::move(fd));
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}
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bool EventFdLinux::empty() {
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return !impl_;
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}
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void EventFdLinux::close() {
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impl_.reset();
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}
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Status EventFdLinux::get_pending_error() {
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return Status::OK();
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}
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PollableFdInfo &EventFdLinux::get_poll_info() {
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return impl_->info;
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}
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// NB: will be called from multiple threads
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void EventFdLinux::release() {
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const uint64 value = 1;
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auto slice = Slice(reinterpret_cast<const char *>(&value), sizeof(value));
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auto native_fd = impl_->info.native_fd().fd();
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auto result = [&]() -> Result<size_t> {
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auto write_res = detail::skip_eintr([&] { return ::write(native_fd, slice.begin(), slice.size()); });
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auto write_errno = errno;
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if (write_res >= 0) {
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return narrow_cast<size_t>(write_res);
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}
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return Status::PosixError(write_errno, PSLICE() << "Write to fd " << native_fd << " has failed");
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}();
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if (result.is_error()) {
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LOG(FATAL) << "EventFdLinux write failed: " << result.error();
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}
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size_t size = result.ok();
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if (size != sizeof(value)) {
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LOG(FATAL) << "EventFdLinux write returned " << value << " instead of " << sizeof(value);
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}
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}
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void EventFdLinux::acquire() {
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impl_->info.get_flags();
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SCOPE_EXIT {
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// Clear flags without EAGAIN and EWOULDBLOCK
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// Looks like it is safe thing to do with eventfd
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get_poll_info().clear_flags(PollFlags::Read());
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};
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uint64 res;
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auto slice = MutableSlice(reinterpret_cast<char *>(&res), sizeof(res));
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auto native_fd = impl_->info.native_fd().fd();
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auto result = [&]() -> Result<size_t> {
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CHECK(slice.size() > 0);
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auto read_res = detail::skip_eintr([&] { return ::read(native_fd, slice.begin(), slice.size()); });
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auto read_errno = errno;
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if (read_res >= 0) {
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CHECK(read_res != 0);
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return narrow_cast<size_t>(read_res);
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}
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if (read_errno == EAGAIN
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#if EAGAIN != EWOULDBLOCK
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|| read_errno == EWOULDBLOCK
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#endif
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) {
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return 0;
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}
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return Status::PosixError(read_errno, PSLICE() << "Read from fd " << native_fd << " has failed");
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}();
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if (result.is_error()) {
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LOG(FATAL) << "EventFdLinux read failed: " << result.error();
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}
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}
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void EventFdLinux::wait(int timeout_ms) {
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pollfd fd;
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fd.fd = get_poll_info().native_fd().fd();
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fd.events = POLLIN;
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poll(&fd, 1, timeout_ms);
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}
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} // namespace detail
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} // namespace td
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#endif
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