msg/async/Event{Poll,Epoll}: move timeout calculation to Timeout.h

This is duplicate code, and it's buggy, but I want to fix only one
copy.

Signed-off-by: Max Kellermann <[email protected]>

Author: MaxKellermann

src/msg/async/EventEpoll.cc

@@ -17,6 +17,7 @@
 #include "common/errno.h"
 #include <fcntl.h>
 #include "EventEpoll.h"
+#include "Timeout.h"
 
 #define dout_subsys ceph_subsys_ms
 
@@ -120,8 +121,7 @@ int EpollDriver::event_wait(std::vector<FiredFileEvent> &fired_events, struct ti
 {
   int retval, numevents = 0;
 
-  retval = epoll_wait(epfd, events, nevent,
-                      tvp ? (tvp->tv_sec*1000 + tvp->tv_usec/1000) : -1);
+  retval = epoll_wait(epfd, events, nevent, timeout_to_milliseconds(tvp));
   if (retval > 0) {
     numevents = retval;
     fired_events.resize(numevents);

src/msg/async/EventPoll.cc

@@ -15,6 +15,7 @@
 
 #include "common/errno.h"
 #include "EventPoll.h"
+#include "Timeout.h"
 
 #include <unistd.h>
 #define dout_subsys ceph_subsys_ms
@@ -161,11 +162,9 @@ int PollDriver::event_wait(std::vector<FiredFileEvent> &fired_events,
 			  struct timeval *tvp) {
   int retval, numevents = 0;
 #ifdef _WIN32
-  retval = WSAPoll(pfds, max_pfds,
-		      tvp ? (tvp->tv_sec*1000 + tvp->tv_usec/1000) : -1);
+  retval = WSAPoll(pfds, max_pfds, timeout_to_milliseconds(tvp));
 #else
-  retval = poll(pfds, max_pfds,
-		      tvp ? (tvp->tv_sec*1000 + tvp->tv_usec/1000) : -1);
+  retval = poll(pfds, max_pfds, timeout_to_milliseconds(tvp));
 #endif
   if (retval > 0) {
     for (int j = 0; j < max_pfds; j++) {

src/msg/async/Timeout.h

@@ -0,0 +1,44 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2024 IONOS SE
+ *
+ * Author: Max Kellermann <[email protected]>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#ifndef CEPH_MSG_TIMEOUT_H
+#define CEPH_MSG_TIMEOUT_H
+
+#include <time.h> // for struct timeval
+
+/**
+ * Convert the given `struct timeval` to milliseconds.
+ *
+ * This is supposed to be used as timeout parameter to system calls
+ * such as poll() and epoll_wait().
+ */
+constexpr int
+timeout_to_milliseconds(const struct timeval &tv) noexcept
+{
+  return tv.tv_sec * 1000 + tv.tv_usec / 1000;
+}
+
+/**
+ * This overload makes the timeout optional; on nullptr, it returns
+ * -1.
+ */
+constexpr int
+timeout_to_milliseconds(const struct timeval *tv) noexcept
+{
+  return tv != nullptr ? timeout_to_milliseconds(*tv) : -1;
+}
+
+#endif