tdlight/tdutils/td/utils/port/detail/EventFdLinux.cpp

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/port/detail/EventFdLinux.h"
char disable_linker_warning_about_empty_file_event_fd_linux_cpp TD_UNUSED;
#ifdef TD_EVENTFD_LINUX
#include "td/utils/logging.h"
#include "td/utils/misc.h"
#include "td/utils/port/detail/NativeFd.h"
#include "td/utils/port/detail/skip_eintr.h"
#include "td/utils/port/PollFlags.h"
#include "td/utils/ScopeGuard.h"
#include "td/utils/Slice.h"
#include <cerrno>
#include <poll.h>
#include <sys/eventfd.h>
#include <unistd.h>
namespace td {
namespace detail {
class EventFdLinuxImpl {
public:
PollableFdInfo info;
};
EventFdLinux::EventFdLinux() = default;
EventFdLinux::EventFdLinux(EventFdLinux &&) = default;
EventFdLinux &EventFdLinux::operator=(EventFdLinux &&) = default;
EventFdLinux::~EventFdLinux() = default;
void EventFdLinux::init() {
auto fd = NativeFd(eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC));
auto eventfd_errno = errno;
LOG_IF(FATAL, !fd) << Status::PosixError(eventfd_errno, "eventfd call failed");
impl_ = make_unique<EventFdLinuxImpl>();
impl_->info.set_native_fd(std::move(fd));
}
bool EventFdLinux::empty() {
return !impl_;
}
void EventFdLinux::close() {
impl_.reset();
}
Status EventFdLinux::get_pending_error() {
return Status::OK();
}
PollableFdInfo &EventFdLinux::get_poll_info() {
return impl_->info;
}
// NB: will be called from multiple threads
void EventFdLinux::release() {
const uint64 value = 1;
auto slice = Slice(reinterpret_cast<const char *>(&value), sizeof(value));
auto native_fd = impl_->info.native_fd().fd();
auto result = [&]() -> Result<size_t> {
auto write_res = detail::skip_eintr([&] { return write(native_fd, slice.begin(), slice.size()); });
auto write_errno = errno;
if (write_res >= 0) {
return narrow_cast<size_t>(write_res);
}
return Status::PosixError(write_errno, PSLICE() << "Write to fd " << native_fd << " has failed");
}();
if (result.is_error()) {
LOG(FATAL) << "EventFdLinux write failed: " << result.error();
}
size_t size = result.ok();
if (size != sizeof(value)) {
LOG(FATAL) << "EventFdLinux write returned " << value << " instead of " << sizeof(value);
}
}
void EventFdLinux::acquire() {
impl_->info.sync_with_poll();
SCOPE_EXIT {
// Clear flags without EAGAIN and EWOULDBLOCK
// Looks like it is safe thing to do with eventfd
get_poll_info().clear_flags(PollFlags::Read());
};
uint64 res;
auto slice = MutableSlice(reinterpret_cast<char *>(&res), sizeof(res));
auto native_fd = impl_->info.native_fd().fd();
auto result = [&]() -> Result<size_t> {
CHECK(slice.size() > 0);
auto read_res = detail::skip_eintr([&] { return ::read(native_fd, slice.begin(), slice.size()); });
auto read_errno = errno;
if (read_res >= 0) {
CHECK(read_res != 0);
return narrow_cast<size_t>(read_res);
}
if (read_errno == EAGAIN
#if EAGAIN != EWOULDBLOCK
|| read_errno == EWOULDBLOCK
#endif
) {
return 0;
}
return Status::PosixError(read_errno, PSLICE() << "Read from fd " << native_fd << " has failed");
}();
if (result.is_error()) {
LOG(FATAL) << "EventFdLinux read failed: " << result.error();
}
}
void EventFdLinux::wait(int timeout_ms) {
detail::skip_eintr_timeout(
[this](int timeout_ms) {
pollfd fd;
fd.fd = get_poll_info().native_fd().fd();
fd.events = POLLIN;
return poll(&fd, 1, timeout_ms);
},
timeout_ms);
}
} // namespace detail
} // namespace td
#endif