pitrou commented on a change in pull request #9633:
URL: https://github.com/apache/arrow/pull/9633#discussion_r588143037
##########
File path: cpp/src/arrow/flight/server.cc
##########
@@ -892,6 +914,25 @@ Status FlightServerBase::Serve() {
impl_->old_signal_handlers_.clear();
impl_->running_instance_ = impl_.get();
+#ifndef _WIN32
+ // Create the self-pipe for signal handlers to use
+ if (pipe(impl_->self_pipe_.data()) != 0) {
Review comment:
We have `CreatePipe` in `arrow/util/io_util.h`, and it does work on
Windows.
##########
File path: cpp/src/arrow/flight/server.cc
##########
@@ -791,16 +799,30 @@ struct FlightServerBase::Impl {
void DoHandleSignal(int signum) {
got_signal_ = signum;
+#ifdef _WIN32
server_->Shutdown();
+#else
+ int saved_errno = errno;
+ // Ignore errors - pipe is nonblocking
+ write(self_pipe_[1], "0", 1);
+ errno = saved_errno;
+#endif
}
+
+#ifndef _WIN32
+ static void WaitForSignals(int fd) {
+ // Wait for a signal handler to write to the pipe
+ int8_t buf[1];
+ read(fd, /*buf=*/buf, /*count=*/1);
Review comment:
This could be fail with `EINTR`. Of course, presumably that's not really
an error here :-)
##########
File path: cpp/src/arrow/flight/server.cc
##########
@@ -892,6 +914,25 @@ Status FlightServerBase::Serve() {
impl_->old_signal_handlers_.clear();
impl_->running_instance_ = impl_.get();
+#ifndef _WIN32
+ // Create the self-pipe for signal handlers to use
+ if (pipe(impl_->self_pipe_.data()) != 0) {
+ return arrow::internal::IOErrorFromErrno(
+ errno, "Could not initialize self-pipe to wait for signals");
+ }
+ // Make write end nonblocking
+ int flags = fcntl(impl_->self_pipe_[1], F_GETFL);
+ if (flags == -1) {
+ return arrow::internal::IOErrorFromErrno(
+ errno, "Could not initialize self-pipe to wait for signals");
+ }
+ flags |= O_NONBLOCK;
+ if (fcntl(impl_->self_pipe_[1], F_SETFL, flags) == -1) {
+ return arrow::internal::IOErrorFromErrno(
+ errno, "Could not initialize self-pipe to wait for signals");
+ }
+ std::thread handle_signals(&Impl::WaitForSignals, impl_->self_pipe_[0]);
Review comment:
Ideally this all would be factored in a RAII object (what happens if
there is an error below?).
##########
File path: cpp/src/arrow/flight/server.cc
##########
@@ -908,7 +949,20 @@ Status FlightServerBase::Serve() {
RETURN_NOT_OK(
SetSignalHandler(impl_->signals_[i],
impl_->old_signal_handlers_[i]).status());
}
-
+#ifndef _WIN32
+ // We don't care if writing is blocked - that means a signal was already
raised
+ if (write(impl_->self_pipe_[1], "0", 1) < 0 && errno != EAGAIN &&
+ errno != EWOULDBLOCK && errno != EINTR) {
+ return arrow::internal::IOErrorFromErrno(errno, "Could not unblock signal
thread");
+ }
+ if (close(impl_->self_pipe_[0]) < 0) {
Review comment:
`FileClose`
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