I have some doubt related to some best practices regarding the asynchronous events. More exactly related to assigning the async modifier to a void method (that triggers an EventHandler)
My app's supposed to work to do some tests on the background and when I finish up the execution to upload my results to my Db.
Before asking the question I've taken a look over here but I still feel that I am doing something wrong.
From what I've tested there is no apparent reason (for my specific case) to apply the async modifier when I am calling the event handler because specifying the async modifier to subscriber's underlying methods it'll 'dial-back' when meeting the first await resuming the program execution until the awaited action finishes up, working perfectly as I wanted.
My doubt came when I started applying (1'st approach) the async modifier to a void method (the WorkerClass) even though it's the event handler, am I doing it wrongly ?
I've done the following test : Made a stored procedure which delays it's execution for about a minute
alter procedure TestStoredProcedure
@WhileValue int
as
begin
set nocount on;
begin transaction
begin try
waitfor delay '00:01';
insert into WhileResults(Value)
values
(@WhileValue)
commit tran;
end try
begin catch
raisError('Error',16,1);
rollback tran;
end catch;
return;
end
go
This is my 1'st approach :
class Program
{
static void Main(string[] args)
{
var workerClass = new WorkerClass();
var engine = new PlaybackEngine();
engine.TestFinishedEventHandler += workerClass.WorkSomething;
engine.TestRun();
}
}
class PlaybackEngine
{
public EventHandler TestFinishedEventHandler;
public void TestRun()
{
var i = 0;
while (i < 10000)
{
Console.WriteLine(i);
i++;
OnTestFinishedEventHandler(i,new EventArgs());
}
}
protected virtual void OnTestFinishedEventHandler(object sender, EventArgs args)
{
TestFinishedEventHandler?.Invoke(sender,args);
}
}
class WorkerClass
{
public async void WorkSomething(object sender, EventArgs args)
{
await UploadToDbAsync((int)sender);
}
private async Task UploadToDbAsync(int i)
{
using (var sqlConn = new SqlConnection("Data Source=EDWARD;Initial Catalog=TestDb;Integrated Security=True"))
using (var sqlCommand = new SqlCommand())
{
sqlConn.Open();
sqlCommand.Connection = sqlConn;
sqlCommand.CommandTimeout = 1000000;
sqlCommand.CommandType = CommandType.StoredProcedure;
sqlCommand.CommandText = "dbo.TestStoredProcedure";
sqlCommand.Parameters.AddWithValue("@WhileValue", i);
await sqlCommand.ExecuteNonQueryAsync();
sqlConn.Close();
}
}
}
My second approach is :
class Program
{
static void Main(string[] args)
{
var workerClass = new WorkerClass();
var engine = new PlaybackEngine();
// engine.TestFinishedEventHandler += workerClass.WorkSomething;
engine.TestFinished += workerClass.WorkSomething;
engine.TestRun();
}
}
class PlaybackEngine
{
public delegate Task TestRunEventHandler(object source, EventArgs args);
public event TestRunEventHandler TestFinished;
public void TestRun()
{
var i = 0;
while (i < 10000)
{
/* Doing some work here */
i++;
OnTestRan(i,new EventArgs());
Console.WriteLine(i);
}
}
protected virtual async void OnTestRan(object source, EventArgs args)
{
//await TestFinished?.Invoke(source, EventArgs.Empty);
if (TestFinished != null)
await TestFinished(source, new EventArgs());
}
}
class WorkerClass
{
public async Task WorkSomething(object sender, EventArgs args)
{
await UploadToDbAsync((int)sender);
}
private async Task UploadToDbAsync(int i)
{
using (var sqlConn = new SqlConnection("Data Source=EDWARD;Initial Catalog=TestDb;Integrated Security=True"))
using (var sqlCommand = new SqlCommand())
{
sqlConn.Open();
sqlCommand.Connection = sqlConn;
sqlCommand.CommandTimeout = 1000000;
sqlCommand.CommandType = CommandType.StoredProcedure;
sqlCommand.CommandText = "dbo.TestStoredProcedure";
sqlCommand.Parameters.AddWithValue("@WhileValue", i);
await sqlCommand.ExecuteNonQueryAsync();
sqlConn.Close();
}
}
