Wake up from Sleep (CreateWaitableTimer) in C#

June 18, 2009

This code isn’t mine, but from a newsgroup posting on Eggheadcafe.com by MVP Willy Denoyette (I couldn’t find a homepage to link). I’m reposting it here for my own benefit, safe in the knowledge it will never disappear unless my database backup corrupts.

The code illustrates how to set a timer to wake your computer up having been sleep’d. It’s tested on Vista and Windows 7 with sleep mode. I haven’t tried it with a laptop or hibernating however.

I’ll be making it into a winforms in the future soon, that sits in the system tray - I’ll update the page and make a google code project when this is done.

	using System;
	using System.Runtime.InteropServices;
	using Microsoft.Win32.SafeHandles;
	using System.Threading;
	using System.ComponentModel;
	namespace ConsoleApplication1
	{
	class Program
	{
	[DllImport("kernel32.dll")]
	public static extern SafeWaitHandle CreateWaitableTimer(IntPtr lpTimerAttributes, bool bManualReset, string lpTimerName);

	[DllImport("kernel32.dll", SetLastError = true)]
	[return: MarshalAs(UnmanagedType.Bool)]
	public static extern bool SetWaitableTimer(SafeWaitHandle hTimer, [In] ref long pDueTime, int lPeriod, IntPtr pfnCompletionRoutine, IntPtr lpArgToCompletionRoutine, bool fResume);

	static void Main(string[] args)
	{
	SetWaitForWakeUpTime();
	}

	static void SetWaitForWakeUpTime()
	{
	DateTime utc = DateTime.Now.AddMinutes(2);
	long duetime = utc.ToFileTime();

	using (SafeWaitHandle handle = CreateWaitableTimer(IntPtr.Zero, true, "MyWaitabletimer"))
	{
	if (SetWaitableTimer(handle, ref duetime, 0, IntPtr.Zero, IntPtr.Zero, true))
	{
	using (EventWaitHandle wh = new EventWaitHandle(false, EventResetMode.AutoReset))
	{
	wh.SafeWaitHandle = handle;
	wh.WaitOne();
	}
	}
	else
	{
	throw new Win32Exception(Marshal.GetLastWin32Error());
	}
	}

	// You could make it a recursive call here, setting it to 1 hours time or similar
	Console.WriteLine("Wake up call");
	Console.ReadLine();
	}
	}
	}

view raw gistfile1.cs hosted with ❤ by GitHub

csharpwinforms

I'm Chris Small, a software engineer working in London. This is my tech blog. Find out more about me via Github, Stackoverflow, Resume