I'm trying to save a rather large text file when the user hits the save button. It can be up to 30MBs. After pressing the button, I'd like the texbox to display "Saving..." as it's saving the file and when it completes, display "Saved". However I can't get this to work. I've tried using Task.run, await task.Run, and using a background worker. All these options hang the UI until the save completes. The textbox does not display "Saving..." until after it saves and the program is unresponsive until then. How can I fix this?
private async void btnSave_Click(object sender, RoutedEventArgs e)
{
SaveFileDialog saveFileDialog1 = new SaveFileDialog();
saveFileDialog1.ShowDialog();
// If the file name is not an empty string open it for saving.
if (saveFileDialog1.FileName != "")
{
logFileName = saveFileDialog1.FileName;
btnOpenFile.IsEnabled = false;
btnSave.IsEnabled = false;
tbText1.Text += "\n\n***Saving...***\n";
tbText1.ScrollToEnd();
await Task.Run(() => File.WriteAllText(logFileName, Results.ToString()));
tbText1.Text += "\n\n***SAVED***\n\n";
tbText1.ScrollToEnd();
btnOpenFile.IsEnabled = true;
btnSave.IsEnabled = true;
}
As discussed in the comments, the problem is with Results.ToString().
I tried to reproduce the issue with this code:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
for (int i = 1; i < 40536; i++)
{
stringBuilder.Append(new string('a', i));
}
}
readonly StringBuilder stringBuilder = new StringBuilder();
int tickNumber = 0;
private void sync_Click(object sender, EventArgs e)
{
button1.Enabled = false;
stringBuilder.ToString();
button1.Enabled = true;
}
private async void async_Click(object sender, EventArgs e)
{
button2.Enabled = false;
await Task.Run(() => stringBuilder.ToString());
button2.Enabled = true;
}
private void timer1_Tick(object sender, EventArgs e)
{
tickNumber %= 50;
tickNumber++;
label1.Text = new string('.', tickNumber);
}
}
But it works as expected:
Sometimes UI hands for a little bit though. Is this what are you talking about?
Try moving code that generates contents for StringBuilder inside the task (so this StringBuilder only exists in background thread)
Related
I've created a new WinForms project in Visual Studio 2017.
Then I've added a button and textbox to Form1 (screenshot).
Code:
using System;
using System.Net;
using System.Windows.Forms;
namespace TestWinForms
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private delegate void FormDelegate();
private void button1_Click(object sender, EventArgs e)
{
UseWaitCursor = true;
button1.Enabled = false;
BeginInvoke(new FormDelegate(delegate
{
using (WebClient web = new WebClient())
{
web.Encoding = System.Text.Encoding.UTF8;
textBox1.Text = web.DownloadString("https://stackoverflow.com/");
}
UseWaitCursor = false;
button1.Enabled = true;
}));
}
}
}
When I click button1 window cursor isn't changing to WaitCursor, and when I hover cursor over ControlBox buttons they aren't "glowing". In short, BeginInvoke() blocks main thread for a moment. Why this is happening and how can I avoid it?
As the fellow users said in the comments, it's DownloadString that's blocking your UI, not BeginInvoke since it waits for the download to complete.
You should probably tackle this in another way, by using DownloadStringAsync:
private WebClient _web;
private void button1_Click(object sender, EventArgs e)
{
UseWaitCursor = true;
button1.Enabled = false;
_web = new WebClient();
_web.Encoding = System.Text.Encoding.UTF8;
_web.DownloadStringCompleted += DownloadCompleted;
_web.DownloadStringAsync("https://stackoverflow.com/");
}
private void DownloadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
textBox1.Text = e.Result;
UseWaitCursor = false;
button1.Enabled = true;
_web.Dispose();
}
I second Hans comment : the BeginInvoke only defer execution later.
What you need is either a BackgroundWorker or (better) using the async/await pattern:
private async void button1_Click(object sender, EventArgs e)
{
UseWaitCursor = true;
button1.Enabled = false;
using (WebClient web = new WebClient())
{
web.Encoding = System.Text.Encoding.UTF8;
textBox1.Text = await web.DownloadStringTaskAsync("https://stackoverflow.com/");
}
UseWaitCursor = false;
button1.Enabled = true;
};
}
The DownloadStringTaskAsync will run on a worker process because it is awaitable. While it runs, the UI thread will continue to process the other events anyway, then continue its execution after the await statement as the DownloadStringTaskAsync finishes.
I have a long running method which I made async. I made my button click handler async as well, but when I try to access my label in my button click after the long method is done, it tells me it can't can't access it from another thread. Here is the code:
private void Migrate()
{
for (int i = 2; i <= excelData.GetUpperBound(0); i++)
{
var poco = new ExpandoObject() as IDictionary<string, object>;
foreach (var column in distributionColumnExcelHeaderMappings)
{
if (column.ColumnIndex > 0)
{
var value = excelData[i,column.ColumnIndex]?.ToString();
poco.Add(column.DistributionColumnName.Replace(" ", ""), value);
}
}
pocos.Add(poco);
}
migrationRepository.BulkInsert(insertToTable, "Id", pocos);
}
private async void btnMigrate_Click(object sender, EventArgs e)
{
Task task = new Task(()=> Migrate());
task.Start();
lblStatus.Text = "Migrating data....";
await task;
lblStatus.Text = "Migration Complete";
}
When the button is clicked, I see the status Migrating data..... When that is complete, it throws an error on lblStatus.Text = "Migration Complete". I thought after await, it goes back to the UI thread?
I cleared out most of the code and it still throws the same error. This is a VSTO excel add-in. Could that be part of the problem?
private void Migrate()
{
}
private async void btnMigrate(object sender, EventArgs e)
{
Task.Run(()=>Migrate());
lblStatus.Text = "Done"; //still get error here
}
Try and update your code to the following:
Instead of creating your task and then starting it manually, update it to just await on Task.Run:
private async void btnMigrate_Click(object sender, EventArgs e)
{
lblStatus.Text = "Migrating data....";
await Task.Run(()=> Migrate());
lblStatus.Text = "Migration Complete";
}
Edit:
You can use a helper method that will check to see if the label needs to be invoked before updating.
private async void btnMigrate_Click(object sender, EventArgs e)
{
SetLabelText(lblStatus, "Migrating data....");
await Task.Run(()=> Migrate());
SetLabelText(lblStatus, "Migration complete.");
}
private void SetLabelText(Label label, string text)
{
if (label.InvokeRequired)
{
label.BeginInvoke((MethodInvoker) delegate() {label.Text = text;});
}
else
{
label.Text = text;
}
}
I have created a Windows Forms program that breaks down a file and sends its components to a server. These files are large, so I created a progressBar so users don't think it froze while the transactions are happening. What I would like to do is have some mechanism that will actively trigger only when all threads are complete without blocking the UI thread (again, so the plebs wont think its frozen). The best I could come up with is a kind of passive "wait until true" but I feel like there has to be a better way to do this. I have experimented with trying to create an event or a callback but honestly I've just ended up more confused than when I started. Here is an example of how I am doing this now:
public partial class Program : Form
{
private readonly OpenFileDialog _ofd = new OpenFileDialog();
public delegate void BarDelegate();
private string _path;
private void button1_Click(object sender, EventArgs e)
{
if (_ofd.ShowDialog() != DialogResult.OK) return;
textBox1.Text = _ofd.SafeFileName;
_path = _ofd.FileName;
}
private void button2_Click(object sender, EventArgs e)
{
var allLinesFromFile = File.ReadAllLines(_path);
progressBar1.Minimum = 0;
progressBar1.Maximum = allLinesFromFile.Length;
Task.Factory.StartNew(() => Parallel.ForEach(allLinesFromFile, DoSomething));
while (progressBar1.Value < progressBar1.Maximum) //there has to be a better way to do this...
{
MessageBox.Show("Please wait.", "Record Poster", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}
//some processes here which should only take place after all threads are complete.
var postingComplete = MessageBox.Show("The posting is complete!", "Record Poster", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
if (postingComplete == DialogResult.OK) Environment.Exit(0);
}
private void DoSomething(string record)
{
//some string manipulation and server transactions here
BeginInvoke(new BarDelegate(() => progressBar1.Increment(1)));
}
}
Try using Microsoft's Reactive Framework (NuGet "System.Reactive.Windows.Forms") for this. Then your code becomes:
private void button2_Click(object sender, EventArgs e)
{
var allLinesFromFile = File.ReadAllLines(_path);
progressBar1.Minimum = 0;
progressBar1.Maximum = allLinesFromFile.Length;
IDisposable subscription =
allLinesFromFile
.ToObservable()
.SelectMany(f => Observable.Start(() => DoSomething(f)))
.ObserveOn(this)
.Do(x => progressBar1.Value += 1)
.Subscribe(x => { }, () =>
{
var postingComplete = MessageBox.Show("The posting is complete!", "Record Poster", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
if (postingComplete == DialogResult.OK)
{
Application.Exit();
}
});
}
private void DoSomething(string record)
{
System.Threading.Thread.Sleep(5);
}
If you need to stop this early then just call subscription.Dispose(). I've tested this and it works fine for me.
You should be using the BackGroundWorker class, see: How to use a BackgroundWorker?
And use BackGroundWorker.RunWorkerComplete for when the thread has finished
Background worker:
**Backgroundworker (System.ComponentModel)**
BackgroundWorker loader = new BackgroundWorker();
loader.DoWork += load_Specials_BW_Thread;
loader.WorkerReportsProgress = true;
loader.ProgressChanged += load_Special_Feeds_Progress_Changed;
private void load_Specials_BW_Thread(object sender, DoWorkEventArgs e)
{
int pctComplete = (int)Math.Floor(ptComplete * 100);//recs done / total recs
(sender as BackgroundWorker).ReportProgress(pctComplete);
}
Good luck!
I've created an application that patches my game servers files.
However, I've got 3 problems which I can't solve:
When downloading a new patch, it doesn't update the progressbar instantly, but refreshes it after around 30-40 seconds
I want a label to show how much mega bytes they are downloading, and how much they have so far (for example: 122Mb/750Mb
When downloading, I want a label to show ~% of how much it has downloaded so far
I am not sure how to add number 2 and 3, and the number 1 problem just seems ridiculous, because there's nothing that indicates it should refresh after 30-40 seconds in my coding (at least as far as I know)
My backgroundWorker1_DoWork:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
//Defines the server's update directory
string Server = "http://localhost/dl/game-updates/";
//Defines application root
string Root = AppDomain.CurrentDomain.BaseDirectory;
//Make sure version file exists
FileStream fs = null;
if (!File.Exists("version"))
{
using (fs = File.Create("version"))
{
}
using (StreamWriter sw = new StreamWriter("version"))
{
sw.Write("1.0");
}
}
//checks client version
string lclVersion;
using (StreamReader reader = new StreamReader("version"))
{
lclVersion = reader.ReadLine();
}
decimal localVersion = decimal.Parse(lclVersion);
//server's list of updates
XDocument serverXml = XDocument.Load(#Server + "Updates.xml");
//The Update Process
foreach (XElement update in serverXml.Descendants("update"))
{
string version = update.Element("version").Value;
string file = update.Element("file").Value;
decimal serverVersion = decimal.Parse(version);
string sUrlToReadFileFrom = Server + file;
string sFilePathToWriteFileTo = Root + file;
if (serverVersion > localVersion)
{
Uri url = new Uri(sUrlToReadFileFrom);
System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
response.Close();
Int64 iSize = response.ContentLength;
Int64 iRunningByteTotal = 0;
using (System.Net.WebClient client = new System.Net.WebClient())
{
using (System.IO.Stream streamRemote = client.OpenRead(new Uri(sUrlToReadFileFrom)))
{
using (Stream streamLocal = new FileStream(sFilePathToWriteFileTo, FileMode.Create, FileAccess.Write, FileShare.None))
{
int iByteSize = 0;
byte[] byteBuffer = new byte[iSize];
while ((iByteSize = streamRemote.Read(byteBuffer, 0, byteBuffer.Length)) > 0)
{
streamLocal.Write(byteBuffer, 0, iByteSize);
iRunningByteTotal += iByteSize;
double dIndex = (double)(iRunningByteTotal);
double dTotal = (double)byteBuffer.Length;
double dProgressPercentage = (dIndex / dTotal);
int iProgressPercentage = (int)(dProgressPercentage * 100);
backgroundWorker1.ReportProgress(iProgressPercentage);
}
streamLocal.Close();
}
streamRemote.Close();
}
}
//unzip
using (ZipFile zip = ZipFile.Read(file))
{
foreach (ZipEntry zipFiles in zip)
{
zipFiles.Extract(Root + "\\", true);
}
}
//download new version file
WebClient webClient = new WebClient();
webClient.DownloadFile(Server + "version.txt", #Root + "version");
//Delete Zip File
deleteFile(file);
}
}
}
My backgroundWorker1_ProgressChanged:
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
label1.Text = "Downloading updates...";
}
And my backgroundWorker1_RunWorkerCompleted:
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
settings_btn.Enabled = true;
start_btn_disabled.Enabled = false;
start_btn_disabled.Visible = false;
start_btn.Visible = true;
start_btn.Enabled = true;
progressBar1.Value = 100;
label1.Text = "Client is up to date!";
}
Also, a side note: I'm also having a bit problems of updating labels in backgroundWorker2_DoWork?
Any ideas?
Here's some working code which updates a label on Form1 using the BackgroundWorker.
Create a new Windows Form project and drop it in your code and it'll work.
It's super ugly, but it works.
After that, just plug your code into the DoWork method and calculate your value and send to ReportProgress.
Keep in mind that the work done in DoWork method is the actual Background Thread.
That means that in that method (DoWork) you cannot access UI (form) elements because they are on the UI thread.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
backgroundWorker1.DoWork += backgroundWorker1_DoWork;
backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
}
void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
button1.Enabled = true;
}
private void button1_Click(object sender, EventArgs e)
{
button1.Enabled = false;
backgroundWorker1.RunWorkerAsync();
}
void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
label1.Text = e.ProgressPercentage.ToString();
}
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
FakeCountingWork();
}
private void FakeCountingWork()
{
int totalNumber = 100;
int progressCounter = 0;
while (progressCounter < totalNumber)
{
int fakecounter = 0;
for (int x = 0; x < 100000000; x++)
{
fakecounter++;
}
progressCounter++;
backgroundWorker1.ReportProgress(progressCounter);
}
}
}
################################## EDITED TO ADD OTHER FUNCTIONALITY
Okay, here's how you can implement a label which displays the number of bytes downloaded so far.
Add a second label named label2 to your form.
Next alter the following methods from my previous example.
Here we are going to use the UserState to pass an extra value to the ProgressChanged Event. It's very simple. You can see that I'm generating a random number and it will now appear in Label2. This is where you could show your number of bytes.
void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
label1.Text = e.ProgressPercentage.ToString();
label2.Text = e.UserState.ToString();
}
private void FakeCountingWork()
{
int totalNumber = 100;
int progressCounter = 0;
Random rnd = new Random();
while (progressCounter < totalNumber)
{
int fakecounter = 0;
for (int x = 0; x < 100000000; x++)
{
fakecounter++;
}
progressCounter++;
updateValue = rnd.Next();
backgroundWorker1.ReportProgress(progressCounter,updateValue);
}
}
I would imagine this is because you are trying to update UI objects on a different thread. HAve you tried using the Dispatcher if using wpf? https://msdn.microsoft.com/en-us/library/system.windows.threading.dispatcher.invoke(v=vs.110).aspx
or Invoke if using Winforms? https://msdn.microsoft.com/fr-ca/library/zyzhdc6b(v=vs.85).aspx
Edit:
As #daylight pointed out to be, the UI was being updated in the progresschanged event, which executes on the thread which created the background worker, therefore there shouldn't be an issue regarding threading. See https://msdn.microsoft.com/en-us/library/ka89zff4(v=vs.110).aspx for more info
private void button1_Click(object sender, EventArgs e)
{
button1.Enabled = false;
string IDs = ID.Text;
string[] eachIDs = Regex.Split(IDs, "\n");
foreach (var eachID in eachIDs)
{
getContent(eachID);
titleBox.Text = "Done";
}
}
private void getContent(string value)
{
label1.Text = value;
Thread.Sleep(5000);
}
I will give 4 id's as Input say "IDNUMBER01, IDNUMBER02, IDNUMBER03, IDNUMBER04" each in a new line in Rich Text Box.
The code splits them successfully. I want to show the Value of the ID being used in the current loop in a Label Text.
Problem with my code is it shows only the last ID which goes through the loop.
Probably your UI freezing and you can't see the changes.Try this, use async/await feature:
private async void button1_Click(object sender, EventArgs e)
{
button1.Enabled = false;
string IDs = ID.Text;
string[] eachIDs = Regex.Split(IDs, "\n");
foreach (var eachID in eachIDs)
{
await getContent(eachID);
titleBox.Text = "Done";
}
}
private async Task getContent(string value)
{
label1.Text = value;
await Task.Delay(5000);
}
This is because the UI is only Updated after the execution of this code, since they are executing in the same thread. You will need to open a thread, run this code, and call the dispatcher (or the Control.BeginInvoke if this app is Winforms) to update the UI.
EDIT
Try this:
private void button1_Click(object sender, EventArgs e)
{
button1.Enabled = false;
string IDs = ID.Text;
new System.Threading.Thread(() =>
{
string[] eachIDs = Regex.Split(IDs, "\n");
foreach (var eachID in eachIDs)
{
getContent(eachID);
titleBox.BeginInvoke((Action) delegate { titleBox.Text = "Done"; });
}
}).Start();
}
private void getContent(string value)
{
label1.BeginInvoke((Action) delegate { label1.Text = value; });
Thread.Sleep(5000);
}
In your example, you'd be better using a timer to display your value text. You're only seeing the last ID because the loop is executing very quickly, and using Thread.Sleep within the foreach isn't going to fly.
You could use Application.DoEvents() before the Thread.Sleep, but a timer is still your better option ... imho.