tdlight/tdutils/td/utils/port/detail/Select.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/Select.h"
char disable_linker_warning_about_empty_file_select_cpp TD_UNUSED;
#ifdef TD_POLL_SELECT
#include "td/utils/logging.h"
#include <utility>
namespace td {
namespace detail {
void Select::init() {
FD_ZERO(&all_fd_);
FD_ZERO(&read_fd_);
FD_ZERO(&write_fd_);
FD_ZERO(&except_fd_);
max_fd_ = -1;
}
void Select::clear() {
fds_.clear();
}
void Select::subscribe(PollableFd fd, PollFlags flags) {
int native_fd = fd.native_fd().fd();
for (auto &it : fds_) {
CHECK(it.fd.native_fd().fd() != native_fd);
}
fds_.push_back(FdInfo{std::move(fd), flags});
LOG_CHECK(0 <= native_fd && native_fd < FD_SETSIZE) << native_fd << " " << FD_SETSIZE;
FD_SET(native_fd, &all_fd_);
if (native_fd > max_fd_) {
max_fd_ = native_fd;
}
}
void Select::unsubscribe(PollableFdRef fd) {
auto fd_locked = fd.lock();
int native_fd = fd_locked.native_fd().fd();
fd_locked.release_as_list_node();
LOG_CHECK(0 <= native_fd && native_fd < FD_SETSIZE) << native_fd << " " << FD_SETSIZE;
FD_CLR(native_fd, &all_fd_);
FD_CLR(native_fd, &read_fd_);
FD_CLR(native_fd, &write_fd_);
FD_CLR(native_fd, &except_fd_);
while (max_fd_ >= 0 && !FD_ISSET(max_fd_, &all_fd_)) {
max_fd_--;
}
for (auto it = fds_.begin(); it != fds_.end();) {
if (it->fd.native_fd().fd() == native_fd) {
std::swap(*it, fds_.back());
fds_.pop_back();
break;
} else {
++it;
}
}
}
void Select::unsubscribe_before_close(PollableFdRef fd) {
unsubscribe(fd);
}
void Select::run(int timeout_ms) {
timeval timeout_data;
timeval *timeout_ptr;
if (timeout_ms == -1) {
timeout_ptr = nullptr;
} else {
timeout_data.tv_sec = timeout_ms / 1000;
timeout_data.tv_usec = timeout_ms % 1000 * 1000;
timeout_ptr = &timeout_data;
}
for (auto &it : fds_) {
int native_fd = it.fd.native_fd().fd();
PollFlags fd_flags = it.fd.get_flags_unsafe(); // concurrent calls are UB
if (it.flags.can_write() && !fd_flags.can_write()) {
FD_SET(native_fd, &write_fd_);
} else {
FD_CLR(native_fd, &write_fd_);
}
if (it.flags.can_read() && !fd_flags.can_read()) {
FD_SET(native_fd, &read_fd_);
} else {
FD_CLR(native_fd, &read_fd_);
}
FD_SET(native_fd, &except_fd_);
}
select(max_fd_ + 1, &read_fd_, &write_fd_, &except_fd_, timeout_ptr);
for (auto &it : fds_) {
int native_fd = it.fd.native_fd().fd();
PollFlags flags;
if (FD_ISSET(native_fd, &read_fd_)) {
flags = flags | PollFlags::Read();
}
if (FD_ISSET(native_fd, &write_fd_)) {
flags = flags | PollFlags::Write();
}
if (FD_ISSET(native_fd, &except_fd_)) {
flags = flags | PollFlags::Error();
}
it.fd.add_flags(flags);
}
}
} // namespace detail
} // namespace td
#endif