thread/Slack: use std::chrono::duration

src/Main.cxx

@@ -589,7 +589,7 @@ mpd_main_after_fork(const ConfigData &raw_config, const Config &config)
 
 	/* the MPD frontend does not care about timer slack; set it to
 	   a huge value to allow the kernel to reduce CPU wakeups */
-	SetThreadTimerSlackMS(100);
+	SetThreadTimerSlack(std::chrono::milliseconds(100));
 
 #ifdef ENABLE_SYSTEMD_DAEMON
 	sd_notify(0, "READY=1");

src/event/Thread.cxx

@@ -52,7 +52,7 @@ EventThread::Run() noexcept
 	SetThreadName(realtime ? "rtio" : "io");
 
 	if (realtime) {
-		SetThreadTimerSlackUS(10);
+		SetThreadTimerSlack(std::chrono::microseconds(10));
 
 		try {
 			SetThreadRealtime();

src/output/Thread.cxx

@@ -410,7 +410,7 @@ AudioOutputControl::Task() noexcept
 		    "OutputThread could not get realtime scheduling, continuing anyway");
 	}
 
-	SetThreadTimerSlackUS(100);
+	SetThreadTimerSlack(std::chrono::microseconds(100));
 
 	std::unique_lock<Mutex> lock(mutex);
 

src/thread/Slack.hxx

 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -22,6 +22,8 @@
 
 #include "config.h"
 
+#include <chrono>
+
 #ifdef HAVE_PRCTL
 #include <sys/prctl.h>
 #endif
@@ -41,16 +43,11 @@ SetThreadTimerSlackNS(unsigned long slack_ns) noexcept
 #endif
 }
 
-static inline void
-SetThreadTimerSlackUS(unsigned long slack_us) noexcept
-{
-	SetThreadTimerSlackNS(slack_us * 1000ul);
-}
-
-static inline void
-SetThreadTimerSlackMS(unsigned long slack_ms) noexcept
+template<class Rep, class Period>
+static inline auto
+SetThreadTimerSlack(const std::chrono::duration<Rep,Period> &slack) noexcept
 {
-	SetThreadTimerSlackNS(slack_ms * 1000000ul);
+	SetThreadTimerSlackNS(std::chrono::duration_cast<std::chrono::nanoseconds>(slack).count());
 }
 
 #endif