C# 3.0 Cookbook, 3rd Edition

9.4. Converting Delegate Invocation from Synchronous to Asynchronous

Problem

You have determined that one or more delegates invoked synchronously within your application are taking a long time to execute. This delay is making the user interface less responsive to the user. The invocation of these delegates should be converted from synchronous to asynchronous mode.

Solution

A typical synchronous delegate type and supporting code that invokes the delegate are shown here:

	public delegate void SyncDelegateTypeSimple();

	public class TestSyncDelegateTypeSimple
	{
	    public static void Method1()
	    {
	        Console.WriteLine("Invoked Method1");
	    }
	}

The code to use this delegate is:

	public static void TestSimpleSyncDelegate()
	{
	    SyncDelegateTypeSimple sdtsInstance = TestSyncDelegateTypeSimple.Method1;
	    sdtsInstance();
	}

This delegate can be called asynchronously on a thread obtained from the thread pool by modifying the code as follows:

	public static void TestSimpleAsyncDelegate()
	{
	    AsyncCallback callBack = new AsyncCallback(DelegateSimpleCallback); SyncDelegateTypeSimple sdtsInstance = TestSyncDelegateTypeSimple.Method1; IAsyncResult asyncResult = sdtsInstance.BeginInvoke(callBack, null); Console.WriteLine("WORKING..."); } // The callback that gets called when TestSyncDelegateTypeSimple.Method1 // is finished processing private static void DelegateSimpleCallback(IAsyncResult iResult) { AsyncResult result = (AsyncResult)iResult; SyncDelegateTypeSimple sdtsInstance = (SyncDelegateTypeSimple)result.AsyncDelegate; ...