我开发了一个存储多个连接字符串的应用程序。我只是迭代for循环并连接每个db并对每个db执行sql。这样我用bulk sql语句更新多个数据库。
现在我需要使用现在的任务并行库来同时更新多个数据库，而不是一个接一个地循环更新。我还想处理异常，并且还希望为多个数据库操作显示多个进度条。暂停＆amp;应该有恢复功能。
当我点击按钮时，将打开多个数据库连接，对于每个任务，我的表单中将添加一个新的进度条。每个进度条将显示每个数据库操作进度。当任何任务完成后，相应的进度条将从表单中删除。
任何人都可以使用TPL指导我如何使用示例代码。 这里我有一个代码更新一个进度条但我需要更新多个进度条。 int iterations = 100;
ProgressBar pb = new ProgressBar();
pb.Maximum = iterations;
pb.Dock = DockStyle.Fill;
Controls.Add(pb);
Task.Create(delegate
{
Parallel.For(0, iterations, i =>
{
Thread.SpinWait(50000000); // do work here
BeginInvoke((Action)delegate { pb.Value++; });
});
});
public partial class Main : Form
{
public Main()
{
InitializeComponent();
this.DoubleBuffered = true;
}
private void btnStart_Click(object sender, EventArgs e)
{
Progress ucProgress = null;
Dictionary<string, string> dicList = new Dictionary<string, string>();
dicList.Add("GB", "conn1");
dicList.Add("US", "conn2");
dicList.Add("DE", "conn3");
fpPanel.Controls.Clear();
Task.Factory.StartNew(() =>
{
foreach (KeyValuePair<string, string> entry in dicList)
{
ucProgress = new Progress();
ucProgress.Country = entry.Key;
ucProgress.DBConnection = entry.Value;
fpPanel.BeginInvoke((MethodInvoker)delegate
{
fpPanel.Controls.Add(ucProgress);
ucProgress.Process();
});
//fpPanel.Controls.Add(ucProgress);
System.Threading.Thread.SpinWait(5000000);
}
});
}
private void Main_Resize(object sender, EventArgs e)
{
this.Invalidate();
}
private void Main_Paint(object sender, PaintEventArgs e)
{
using (LinearGradientBrush brush = new LinearGradientBrush(this.ClientRectangle,
Color.WhiteSmoke,
Color.LightGray,
90F))
{
e.Graphics.FillRectangle(brush, this.ClientRectangle);
}
}
}
public partial class Progress : UserControl
{
public Progress()
{
InitializeComponent();
lblMsg.Text = "";
pbStatus.Minimum = 0;
pbStatus.Maximum = 100;
}
public string Country { get; set; }
public string DBConnection { get; set; }
public string Sql { get; set; }
public void SetMessage(string strMsg)
{
lblMsg.Text = strMsg;
}
public void Process()
{
var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
Task.Factory.StartNew(() =>
{
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "Connecting country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 30;
});
System.Threading.Thread.SpinWait(50000000);
//***********
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "executing sql for country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 60;
});
System.Threading.Thread.SpinWait(50000000);
//***********
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "sql executed successfully for country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 100;
});
System.Threading.Thread.SpinWait(50000000);
});
//System.Threading.Thread.SpinWait(50000000); // do work here
}
}
答案 0 :(得分：2)
var cancellationTokenSource = new CancellationTokenSource();
var cancellation = cancellationTokenSource.Token;
void UpdateDatabases(IEnumerable<...> databases, CancellationToken cancellation)
{
foreach(db in databases)
{
//create as many ProgressBar instances as databases you want to update
//check if ProgressBar exist, then return it and reuse, otherwise create new
ProgressBar pb = new ProgressBar();
pb.Maximum = iterations;
pb.Dock = DockStyle.Fill;
Controls.Add(pb);
//start thread for every database/progress bar
Task.Factory.StartNew(progressBar =>
{
var start = (ProgressBar)progressBar).Value; //use last value in case of pause
Parallel.For(start, iterations,
new ParallelOptions(){CancellationToken = cancellation}
(i, loopState) =>
{
if (loopState.ShouldExitCurrentIteration)
return;
//perhaps check loopState.ShouldExitCurrentIteration inside worker method
Thread.SpinWait(50000000); // do work here
BeginInvoke((Action)delegate { ((ProgressBar)progressBar).Value++; });
});
},
pb, cancellation)
.ContinueWith(task =>
{
//to handle exceptions use task.Exception member
var progressBar = (ProgressBar)task.AsyncState;
if (!task.IsCancelled)
{
//hide progress bar here and reset pb.Value = 0
}
},
TaskScheduler.FromCurrentSynchronizationContext() //update UI from UI thread
);
}
}
//.........
//Call
UpdateDatabases(databases, cancellation)
//To suspend, call
cancellationTokenSource.Cancel();
//To resume - simply call UpdateDatabases again
cancellationTokenSource = new CancellationTokenSource();
cancellation = cancellationTokenSource.Token;
UpdateDatabases(databases, cancellation)
<强>更新
我查看了您的代码。查看重新访问的代码并根据您的需求进行调整。主要错误 - 混淆closures并从非ui线程创建进度。要启用并行处理，可以使用Parallel.ForEach（有关可能的重载，请参阅MSND）。对我来说，这个设计看起来有点奇怪（你在Progress中混合了数据和逻辑）。从UI的角度来看，进度条按处理顺序出现但不是原始顺序也很奇怪，因为它们在列表中（如果您决定按字母顺序对列表进行排序，则会出现问题）
我希望它有所帮助。
主要代码
private void btnStart_Click(object sender, EventArgs e)
{
Progress ucProgress = null;
Dictionary<string, string> dicList = new Dictionary<string, string>();
dicList.Add("GB", "conn1");
dicList.Add("US", "conn2");
dicList.Add("DE", "conn3");
fpPanel.Controls.Clear();
Func<KeyValuePair<string, string>, object> createProgress = entry =>
{
var tmp = new Progress {Country = entry.Key, DBConnection = entry.Value};
fpPanel.Controls.Add(tmp);
return tmp;
};
Task.Factory.StartNew(() =>
{
//foreach (KeyValuePair<string, string> entry in dicList)
Parallel.ForEach(dicList,
entry =>
{
//create and add the Progress in UI thread
var ucProgress = (Progress)fpPanel.Invoke(createProgress, entry);
//execute ucProgress.Process(); in non-UI thread in parallel.
//the .Process(); must update UI by using *Invoke
ucProgress.Process();
System.Threading.Thread.SpinWait(5000000);
});
});
}
用户控制代码
public void Process()
{
//uiScheduler - Not used
//var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
//The Task is not necessary because the Process() called from Parallel.ForEach
//Task.Factory.StartNew(() =>
//{
//BeginInvoke or Invoke required
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "Connecting country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 30;
});
System.Threading.Thread.SpinWait(50000000);
//***********
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "executing sql for country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 60;
});
System.Threading.Thread.SpinWait(50000000);
//***********
lblMsg.BeginInvoke((MethodInvoker)delegate
{
lblMsg.Text = "sql executed successfully for country " + Country;
});
pbStatus.BeginInvoke((MethodInvoker)delegate
{
pbStatus.Value = 100;
});
System.Threading.Thread.SpinWait(50000000);
//});
//System.Threading.Thread.SpinWait(50000000); // do work here
}