lix/src/libutil/monitor-fd.hh
John Ericson f4ab297b31 Ensure all headers have #pragma once and are in API docs
`///@file` makes them show up in the internal API dos. A tiny few were
missing `#pragma once`.
2023-03-31 23:19:44 -04:00

70 lines
1.8 KiB
C++

#pragma once
///@file
#include <thread>
#include <atomic>
#include <cstdlib>
#include <poll.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
namespace nix {
class MonitorFdHup
{
private:
std::thread thread;
public:
MonitorFdHup(int fd)
{
thread = std::thread([fd]() {
while (true) {
/* Wait indefinitely until a POLLHUP occurs. */
struct pollfd fds[1];
fds[0].fd = fd;
/* Polling for no specific events (i.e. just waiting
for an error/hangup) doesn't work on macOS
anymore. So wait for read events and ignore
them. */
fds[0].events =
#ifdef __APPLE__
POLLRDNORM
#else
0
#endif
;
auto count = poll(fds, 1, -1);
if (count == -1) abort(); // can't happen
/* This shouldn't happen, but can on macOS due to a bug.
See rdar://37550628.
This may eventually need a delay or further
coordination with the main thread if spinning proves
too harmful.
*/
if (count == 0) continue;
if (fds[0].revents & POLLHUP) {
triggerInterrupt();
break;
}
/* This will only happen on macOS. We sleep a bit to
avoid waking up too often if the client is sending
input. */
sleep(1);
}
});
};
~MonitorFdHup()
{
pthread_cancel(thread.native_handle());
thread.join();
}
};
}