I have achieved the required functionality (that message box was offering me) using a message pump (though this is not a preferred approach).
This is mainly based on following two - Which blocking operations cause an STA thread to pump COM messages? and How to wait for WaitHandle while serving WPF Dispatcher events?
CODE
Note: Add reference to WindowsBase dll in the project
public partial class Form1 : Form
{
int logNumber = 0;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
WriteLogFunction("**");
try
{
while (true)
{
WriteLogFunction("**");
MessagePumpHelper.PumpMessage(1000);
WriteLogFunction(">>");
}
}
catch (Exception ex)
{
WriteLogFunction(ex.Message);
WriteLogFunction(ex.InnerException.ToString());
}
}
private void WriteLogFunction(string strMessage)
{
string fileName = "MYLog_" + DateTime.Now.ToString("yyyyMMMMdd");
fileName = fileName + ".txt";
using (StreamWriter w = File.AppendText(fileName))
{
w.WriteLine("\r\n{0} ..... {1} + {2}ms >>> {3} ", logNumber.ToString(), DateTime.Now.ToLongTimeString(), DateTime.Now.Millisecond.ToString(), strMessage);
logNumber++;
}
}
}
#region WaitExt
public static class MessagePumpHelper
{
public static void PumpMessage(int milliSecondsWait)
{
var dummy = new ManualResetEvent(false);
WaitExt.WaitOneAndPump(dummy, milliSecondsWait);
}
}
// WaitOneAndPump
public static class WaitExt
{
public static bool WaitOneAndPump(this WaitHandle handle, int millisecondsTimeout)
{
using (var operationPendingMre = new ManualResetEvent(false))
{
var result = false;
var startTick = Environment.TickCount;
//using System.Windows.Threading; //From WindowsBase dll
var dispatcher = Dispatcher.CurrentDispatcher;
var frame = new DispatcherFrame();
var handles = new[] {
handle.SafeWaitHandle.DangerousGetHandle(),
operationPendingMre.SafeWaitHandle.DangerousGetHandle() };
// idle processing plumbing
//using System.Windows.Threading; //From WindowsBase dll
DispatcherOperation idleOperation = null;
Action idleAction = () => { idleOperation = null; };
Action enqueIdleOperation = () =>
{
if (idleOperation != null)
idleOperation.Abort();
// post an empty operation to make sure that
// onDispatcherInactive will be called again
idleOperation = dispatcher.BeginInvoke(
idleAction,
DispatcherPriority.ApplicationIdle);
};
// timeout plumbing
Func<uint> getTimeout;
if (Timeout.Infinite == millisecondsTimeout)
getTimeout = () => INFINITE;
else
getTimeout = () => (uint)Math.Max(0, millisecondsTimeout + startTick - Environment.TickCount);
//using System.Windows.Threading; //From WindowsBase dll
DispatcherHookEventHandler onOperationPosted = (s, e) =>
{
// this may occur on a random thread,
// trigger a helper event and
// unblock MsgWaitForMultipleObjectsEx inside onDispatcherInactive
operationPendingMre.Set();
};
//using System.Windows.Threading; //From WindowsBase dll
DispatcherHookEventHandler onOperationCompleted = (s, e) =>
{
// this should be fired on the Dispather thread
Debug.Assert(Thread.CurrentThread == dispatcher.Thread);
// do an instant handle check
var nativeResult = WaitForSingleObject(handles[0], 0);
if (nativeResult == WAIT_OBJECT_0)
result = true;
else if (nativeResult == WAIT_ABANDONED_0)
throw new AbandonedMutexException(-1, handle);
else if (getTimeout() == 0)
result = false;
else if (nativeResult == WAIT_TIMEOUT)
return;
else
throw new InvalidOperationException("WaitForSingleObject");
// end the nested Dispatcher loop
frame.Continue = false;
};
EventHandler onDispatcherInactive = (s, e) =>
{
operationPendingMre.Reset();
// wait for the handle or a message
var timeout = getTimeout();
var nativeResult = MsgWaitForMultipleObjectsEx(
(uint)handles.Length, handles,
timeout,
QS_EVENTMASK,
MWMO_INPUTAVAILABLE);
if (nativeResult == WAIT_OBJECT_0)
// handle signalled
result = true;
else if (nativeResult == WAIT_TIMEOUT)
// timed out
result = false;
else if (nativeResult == WAIT_ABANDONED_0)
// abandonded mutex
throw new AbandonedMutexException(-1, handle);
else if (nativeResult == WAIT_OBJECT_0 + 1)
// operation posted from another thread, yield to the frame loop
return;
else if (nativeResult == WAIT_OBJECT_0 + 2)
{
// a Windows message
if (getTimeout() > 0)
{
// message pending, yield to the frame loop
enqueIdleOperation();
return;
}
// timed out
result = false;
}
else
// unknown result
throw new InvalidOperationException("MsgWaitForMultipleObjectsEx");
// end the nested Dispatcher loop
frame.Continue = false;
};
dispatcher.Hooks.OperationCompleted += onOperationCompleted;
dispatcher.Hooks.OperationPosted += onOperationPosted;
dispatcher.Hooks.DispatcherInactive += onDispatcherInactive;
try
{
// onDispatcherInactive will be called on the new frame,
// as soon as Dispatcher becomes idle
enqueIdleOperation();
//using System.Windows.Threading; //From WindowsBase dll
Dispatcher.PushFrame(frame);
}
finally
{
if (idleOperation != null)
idleOperation.Abort();
dispatcher.Hooks.OperationCompleted -= onOperationCompleted;
dispatcher.Hooks.OperationPosted -= onOperationPosted;
dispatcher.Hooks.DispatcherInactive -= onDispatcherInactive;
}
return result;
}
}
const uint QS_EVENTMASK = 0x1FF;
const uint MWMO_INPUTAVAILABLE = 0x4;
const uint WAIT_TIMEOUT = 0x102;
const uint WAIT_OBJECT_0 = 0;
const uint WAIT_ABANDONED_0 = 0x80;
const uint INFINITE = 0xFFFFFFFF;
[DllImport("user32.dll", SetLastError = true)]
static extern uint MsgWaitForMultipleObjectsEx(
uint nCount, IntPtr[] pHandles,
uint dwMilliseconds, uint dwWakeMask, uint dwFlags);
[DllImport("kernel32.dll")]
static extern uint WaitForSingleObject(IntPtr hHandle, uint dwMilliseconds);
}
#endregion
References
- Which blocking operations cause an STA thread to pump COM messages?
- How to wait for WaitHandle while serving WPF Dispatcher events?
- What is the difference between ManualResetEvent and AutoResetEvent in .NET?
- C# - System.Windows.Forms.Clipboard.GetDataObject() doesnt response
- Timer just works if call MessageBox.Show()
- Synchronizing calls to the UI in a multi-threaded application
