Typesafe fire-and-forget asynchronous delegate invocation in C#
- by LBushkin
I recently found myself needing a typesafe "fire-and-forget" mechanism for running code asynchronously.
Ideally, what I would want to do is something like:
var myAction = (Action)(() => Console.WriteLine("yada yada"));
myAction.FireAndForget(); // async invocation
Unfortunately, the obvious choice of calling BeginInvoke() without a corresponding EndInvoke() does not work - it results in a slow resource leak (since the asyn state is held by the runtime and never released ... it's expecting an eventual call to EndInvoke(). I also can't run the code on the .NET thread pool because it may take a very long time to complete (it's advised to only run relatively short-lived code on the thread pool) - this makes it impossible to use the ThreadPool.QueueUserWorkItem().
Initially, I only needed this behavior for methods whose signature matches Action, Action<...>, or Func<...>. So I put together a set of extension methods (see listing below) that let me do this without running into the resource leak. There are overloads for each version of Action/Func.
Unfortunately, I now want to port this code to .NET 4 where the number of generic parameters on Action and Func have been increased substantially. Before I write a T4 script to generate these, I was also hoping to find a simpler more elegant way to do this. Any ideas are welcome.
public static class AsyncExt
{
public static void FireAndForget( this Action action )
{
action.BeginInvoke(OnActionCompleted, action);
}
public static void FireAndForget<T1>( this Action<T1> action, T1 arg1 )
{
action.BeginInvoke(arg1, OnActionCompleted<T1>, action);
}
public static void FireAndForget<T1,T2>( this Action<T1,T2> action, T1 arg1, T2 arg2 )
{
action.BeginInvoke(arg1, arg2, OnActionCompleted<T1, T2>, action);
}
public static void FireAndForget<TResult>(this Func<TResult> func, TResult arg1)
{
func.BeginInvoke(OnFuncCompleted<TResult>, func);
}
public static void FireAndForget<T1,TResult>(this Func<T1, TResult> action, T1 arg1)
{
action.BeginInvoke(arg1, OnFuncCompleted<T1,TResult>, action);
}
// more overloads of FireAndForget<..>() for Action<..> and Func<..>
private static void OnActionCompleted( IAsyncResult result )
{
var action = (Action)result.AsyncState;
action.EndInvoke(result);
}
private static void OnActionCompleted<T1>( IAsyncResult result )
{
var action = (Action<T1>)result.AsyncState;
action.EndInvoke( result );
}
private static void OnActionCompleted<T1,T2>(IAsyncResult result)
{
var action = (Action<T1,T2>)result.AsyncState;
action.EndInvoke(result);
}
private static void OnFuncCompleted<TResult>( IAsyncResult result )
{
var func = (Func<TResult>)result.AsyncState;
func.EndInvoke( result );
}
private static void OnFuncCompleted<T1,TResult>(IAsyncResult result)
{
var func = (Func<T1, TResult>)result.AsyncState;
func.EndInvoke(result);
}
// more overloads of OnActionCompleted<> and OnFuncCompleted<>
}
