Witam. Ze strony link mam przykład.
Kiedy pytam bazę o około milion danych na słabym pececie zapytanie trwa około 13 s i na tyle zatrzymuje się program.
Teraz chciałem nauczyć się tasków znalazłem świetny przykład ale coś jest nie tak, ponieważ w tym programie przez pierwszych 6 sekund aplikacja jest ok później zamraża się na około 6-8 s.
Pytanie czy ten przykład jest OK czy coś muszę jeszcze doczytać.
Po uproszczeniu wygląda tak :
namespace ASyncAwaitTest
{
public partial class frmTestForm : System.Windows.Forms.Form
{
#region Form Initialize Code
//Event handlers and form initialization code
private int m_QueryNumber = 0;
public frmTestForm()
{
InitializeComponent();
}
private void timer_Tick(object sender, EventArgs e)
{
if (progress.Value < progress.Maximum)
progress.Increment(5);
else
progress.Value = progress.Minimum;
}
#endregion
//Main procedure which demonstrates the async/await operations
private async Task Execute()
{
//Start
m_QueryNumber += 1; var iQueryNumber = m_QueryNumber;
timer.Start(); //progress bar for basic visual feedback.
AddLogItem("Started query " + iQueryNumber + " at " + DateTime.Now.ToString());
//Results to table:
await ResultsToGrid(iQueryNumber);
//Finished
timer.Stop(); progress.Value = progress.Minimum; //progress bar for basic visual feedback.
AddLogItem("Finished query " + iQueryNumber + " at " + DateTime.Now.ToString());
}
//Results to grid
private async Task ResultsToGrid(int iQuery)
{
CDatabase database = new CDatabase();
try
{
//Using task function to get dataset asynchronously.
DataSet results = await database.GetDataSetAsync(txtConnectionString.Text, txtSQLQuery.Text);
//Now that we have our data populate to new tab.
// PopulateGridResultsAS(iQuery, results.Tables[0]);
dataGridView6.Columns.Clear();
dataGridView6.DataSource = results.Tables[0].DefaultView;
}
catch (SqlException sqlError)
{
//In this case our task function is set to pass the error through to the caller, log error to list.
AddLogItem("ResultsToTable Error: " + sqlError.Message);
}
}
//Add item to log.
private void AddLogItem(string sItem)
{
lstResults.Items.Add(sItem);
lstResults.SelectedIndex = lstResults.Items.Count - 1;
}
private void PopulateGridResultsAS(int iQueryId, DataTable dtResult)
{
dataGridView6.Columns.Clear();
dataGridView6.DataSource = dtResult.DefaultView;
}
//Add new tab with DataGrid and populate with results from data table.
private void PopulateGridResults(int iQueryId, DataTable dtResult)
{
//Add as new tab
string sPageId = "Page" + iQueryId;
string sPage = "Result Page " + iQueryId;
tabby.TabPages.Add(sPageId, sPage);
DataGridView results = new DataGridView()
{
Dock = System.Windows.Forms.DockStyle.Fill,
Name = "grd" + sPageId,
ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize
};
tabby.TabPages[sPageId].Controls.Add(results);
results.DataSource = dtResult;
tabby.SelectedTab = tabby.TabPages[sPageId];
}
private async void btnExecute_Click_1(object sender, EventArgs e)
{
txtConnectionString.Text = "server=131.107.3.171;user=asadmin;database=argo_techniczna;password=asbaza";
timer.Tick += timer_Tick;
await Execute();
}
}
}
Klasa po uproszczeniu
class CDatabase
{
// USE CUSTOM CLASS TO RETURN DATA
public class CDatabaseResult
{
public bool Success;
public string Result;
public object Data;
}
// RETURN DATASET
public Task<DataSet> GetDataSetAsync(string sConnectionString, string sSQL, params SqlParameter[] parameters)
{
return Task.Run(() =>
{
using (var newConnection = new SqlConnection(sConnectionString))
using (var mySQLAdapter = new SqlDataAdapter(sSQL, newConnection))
{
mySQLAdapter.SelectCommand.CommandType = CommandType.Text;
if (parameters != null) mySQLAdapter.SelectCommand.Parameters.AddRange(parameters);
DataSet myDataSet = new DataSet();
mySQLAdapter.Fill(myDataSet);
return myDataSet;
}
});
}
}
SQL 
C# 
