![Ge]ng
Informa$on
About
the
Current
Thread
using System;
using System.Threading;
class MyMain
{
public static void Main()
{
Thread.CurrentThread.Name = "My THREAD!";
Console.WriteLine("Name: ");
Console.WriteLine(Thread.CurrentThread.Name);
Console.WriteLine("IsAlive: ");
Console.WriteLine(Thread.CurrentThread.IsAlive);
Console.WriteLine("Priority: ");
Console.WriteLine(Thread.CurrentThread.Priority);
Console.WriteLine("ThreadState: ");
Console.WriteLine(Thread.CurrentThread.ThreadState);
}
}](https://image.slidesharecdn.com/04-multithreading-pptx-130212035159-phpapp02/75/NET-Multithreading-and-File-I-O-13-2048.jpg)
![private void Button_Click_2(object sender, RoutedEventArgs e)
{
Thread t = new Thread(new ThreadStart(ModifyTitle));
t.Start();
}
public void ModifyTitle()
{
Thread.Sleep(1000);
// Change title to "Hello"
Dispatcher.Invoke(new Action(ChangeTitle));
Thread.Sleep(1000);
// Lambda
Dispatcher.Invoke(() => this.Title = "World");
Thread.Sleep(1000);
Dispatcher.Invoke(() => this.Title = "");
string newTitle = "Hello World!";
for (int i = 0; i < newTitle.Length; i++)
{
Thread.Sleep(100);
Dispatcher.Invoke(() => this.Title += newTitle[i]);
}
}
public void ChangeTitle()
{
this.Title = "Hello";
}](https://image.slidesharecdn.com/04-multithreading-pptx-130212035159-phpapp02/75/NET-Multithreading-and-File-I-O-23-2048.jpg)
![using
System;
using
System.IO;
using
System.Run$me.Serializa$on.FormaZers.Binary;
[Serializable]
class
Person
{
public
string
Name
{
get;
set;
}
public
int
Age
{
get;
set;
}
}
class
SerializableExample
{
public
sta$c
void
Main()
{
Person
jack
=
new
Person()
{
Name
=
"Jack",
Age
=
20
};
//
Let's
save
jack
as
binary
BinaryFormaZer
binFormat
=
new
BinaryFormaZer();
//
And
in
which
file?
using(FileStream
fs
=
new
FileStream("person.dat",
FileMode.Create))
{
//
Let's
do
it!
binFormat.Serialize(fs,
jack);
}
}
}](https://image.slidesharecdn.com/04-multithreading-pptx-130212035159-phpapp02/75/NET-Multithreading-and-File-I-O-42-2048.jpg)
![using
System;
using
System.IO;
using
System.Run$me.Serializa$on.FormaZers.Binary;
[Serializable]
class
Person
{
public
string
Name
{
get;
set;
}
public
int
Age
{
get;
set;
}
}
class
SerializableExample
{
public
sta$c
void
Main()
{
BinaryFormaZer
binFormat
=
new
BinaryFormaZer();
//
Deserialize!
using(FileStream
fs
=
new
FileStream("person.dat",
FileMode.Open))
{
Person
jack2
=
(Person)
binFormat.Deserialize(fs);
Console.WriteLine(jack2.Name);
Console.WriteLine(jack2.Age);
}
}
}](https://image.slidesharecdn.com/04-multithreading-pptx-130212035159-phpapp02/75/NET-Multithreading-and-File-I-O-43-2048.jpg)
Uploaded byJussi Pohjolainen
.NET Multithreading and File I/O
This document discusses multithreaded and asynchronous programming in C# and file I/O. It covers delegates and how they allow invoking methods asynchronously on separate threads. It also discusses the Threading namespace which provides classes for creating and managing threads like Thread, ThreadStart, and Timer. The document shows examples of getting thread information, passing parameters to threads, locking for thread safety, and using the Dispatcher class to update the UI from a non-UI thread.
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.NET Multithreading and File I/O
- 1. Mul$threaded and Async Programming in C# + File IO Jussi Pohjolainen Tampere University of Applied Sciences
- 2. Delegates • You can invoke a method (determined by run$me) from a delegate public delegate int SomeMethod(int x, int y); Console.WriteLine("Thread is " + Thread.CurrentThread.ManagedThreadId); SomeMethod a = new SomeMethod(Sum); Console.WriteLine( a.Invoke(5,5) ); • It's possible to make the invoke in separate thread!
- 3. Asynchronous Delegate • By using the same delegate, but calling BeginInvoke, the method is done in separate thread – public IAsyncResult BeginInvoke(parameters.., AsyncCallback cb, object state) – public returnType EndInvoke(IAsyncResult result) • If the method returns something, use EndInvoke to get the return value.
- 4. using System; using System.Threading; publicdelegate int SomeMethod(int x, int y); class MyMain { public static void Main() { SomeMethod a = new SomeMethod(Sum); Console.WriteLine("Firing Asynchronous method"); // IAsyncResult - Represents the status of an asynchronous operation. IAsyncResult iftAR = a.BeginInvoke(5, 5, null, null); Console.WriteLine("Doing some work here!"); int answer = a.EndInvoke(iftAR); Console.WriteLine(answer); } public static int Sum(int x, int y) { Console.WriteLine("Thread is " + Thread.CurrentThread.ManagedThreadId); Thread.Sleep(2000); return x + y; } }
- 5. Synchronizing Calling Thread • If we look at this more closely – Console.WriteLine("Firing Asynchronous method"); – IAsyncResult iftAR = a.BeginInvoke(5, 5, null, null); – Console.WriteLine("Doing some work here!"); – // We are waiting here! – int answer = a.EndInvoke(iftAR); • We realize that the a.EndInvoke waits un$l the "calcula$on" is done
- 6. using System; using System.Threading; publicdelegate int SomeMethod(int x, int y); class MyMain { public static void Main() { SomeMethod a = new SomeMethod(Sum); Console.WriteLine("Firing Asynchronous method"); IAsyncResult iftAR = a.BeginInvoke(5, 5, null, null); while(!iftAR.IsCompleted) { Console.WriteLine("Doing some work here!"); } int answer = a.EndInvoke(iftAR); Console.WriteLine(answer); } public static int Sum(int x, int y) { Console.WriteLine("Thread is " + Thread.CurrentThread.ManagedThreadId); Thread.Sleep(2000); return x + y; } }
- 7. Rid of Polling • Instead of polling, it would be a good idea to have a secondary thread to inform the calling thread when the task is finished.
- 8. using System; using System.Threading; publicdelegate int SomeMethod(int x, int y); class MyMain { private static bool done = false; public static void Main() { SomeMethod a = new SomeMethod(Sum); Console.WriteLine("Firing Asynchronous method"); IAsyncResult iftAR = a.BeginInvoke(5, 5, new AsyncCallback(Done), null); while(!done) { Console.WriteLine("Doing some work here!"); } int answer = a.EndInvoke(iftAR); Console.WriteLine(answer); } public static int Sum(int x, int y) { Console.WriteLine("Thread is " + Thread.CurrentThread.ManagedThreadId); Thread.Sleep(2000); return x + y; } public static void Done(IAsyncResult result) { done = true; } }
- 9. using System; using System.Threading; usingSystem.Runtime.Remoting.Messaging; public delegate int SomeMethod(int x, int y); class MyMain { private static bool done = false; public static void Main() { SomeMethod a = new SomeMethod(Sum); Console.WriteLine("Firing Asynchronous method"); // Passing custom state data a.BeginInvoke(5, 5, new AsyncCallback(Done), "Message Sending!"); while(!done) { Console.WriteLine("Doing some work here!"); } } public static void Done(IAsyncResult iftAR) { // IAsyncResult is interface, actual object is AsyncResult AsyncResult ar = (AsyncResult) iftAR; // AsyncResult holds the delegate SomeMethod sm = (SomeMethod) ar.AsyncDelegate; // Make the call int answer = sm.EndInvoke(iftAR); Console.WriteLine(answer); // Also print the message! string msg = (string) iftAR.AsyncState; Console.WriteLine(msg); done = true; } }
- 10.
- 11. Threading Namespace • Threading namespace provides lot of classes for crea$ng threads – Thread – Main class for crea$ng a thread – ThreadStart – delegate used to specify which method is run under a thread – Timer – Mechanism for execu$ng a method at specified intervals – Lot of locking mechanisms
- 12. System.Threading.Thread Class • Some sta$c members – CurrentThread – get the current thread – Sleep() – Suspend current thread • Some AZributes – IsAlive – Name – Priority • Some Methods – Abort() – Join() – Start() – …
- 13. Ge]ng Informa$on About the Current Thread using System; using System.Threading; class MyMain { public static void Main() { Thread.CurrentThread.Name = "My THREAD!"; Console.WriteLine("Name: "); Console.WriteLine(Thread.CurrentThread.Name); Console.WriteLine("IsAlive: "); Console.WriteLine(Thread.CurrentThread.IsAlive); Console.WriteLine("Priority: "); Console.WriteLine(Thread.CurrentThread.Priority); Console.WriteLine("ThreadState: "); Console.WriteLine(Thread.CurrentThread.ThreadState); } }
- 14. using System; using System.Threading; publicclass Simple { public static void DoThis() { int i=0; while (true) { Console.WriteLine("Running in its own thread. " + i); Thread.Sleep(500); i++; } } public static void Main() { Thread aThread = new Thread(new ThreadStart(DoThis)); aThread.Start(); Thread bThread = new Thread(new ThreadStart(DoThis)); bThread.Start(); } }
- 15. using System; using System.Threading; publicclass Simple { public static void DoThis(object data) { int i=0; while (i < (int) data) { Console.WriteLine("Running in its own thread. " + i); Thread.Sleep(500); i++; } } public static void Main() { Thread aThread = new Thread(new ParameterizedThreadStart(DoThis)); aThread.Start(10); } }
- 16. About Locking • When mul$ple threads access same informa$on -‐> unstable data • Example: one bank account, two withdrawals at the same $me – 1) is there enough money? – 2) if true, withdraw • We have a problem if these steps are done at the same $me: 1,1,2,2
- 17. Solu$on • One solu$on is to use lock keyword • If on thread holds a lock, others wait • lock is any object • Usage lock(object){ }
- 18. Timers using System; usingSystem.Threading; class Hello { public static void DoThis(object data) { Console.WriteLine("Hello!"); } public static void Main() { TimerCallback timeCB = new TimerCallback(DoThis); Timer t = new Timer(timeCB, // call back delegate object null, // Any info to the method 0, // Time before first invocation 1000); // Interval Console.ReadLine(); } }
- 19. Background Worker • hZp://msdn.microsog.com/en-‐us/library/cc221403(v=vs.95).aspx private void Button_Click_2(object sender, RoutedEventArgs e) { BackgroundWorker bw = new BackgroundWorker(); bw.DoWork += DoTheWork; bw.RunWorkerCompleted += Complete; bw.RunWorkerAsync(); } public void DoTheWork(object sender, DoWorkEventArgs e) { Thread.Sleep(500); } public void Complete(object sender, RunWorkerCompletedEventArgs e) { Title = "Hello"; }
- 20.
- 21. Access UI from Thread • If a secondary thread aZempt to access a control it did not create => run$me error! private void Button_Click_2(object sender, RoutedEventArgs e) { Thread thread = new Thread(new ThreadStart(ModifyTitle)); thread.Start(); } // Runtime Exception! public void ModifyTitle() { Title = "Hello World"; }
- 22. Dispatcher Class • Dispatcher class allows you to modify UI from secondary thread • Read – hZp://msdn.microsog.com/en-‐us/magazine/ cc163328.aspx
- 23. private void Button_Click_2(objectsender, RoutedEventArgs e) { Thread t = new Thread(new ThreadStart(ModifyTitle)); t.Start(); } public void ModifyTitle() { Thread.Sleep(1000); // Change title to "Hello" Dispatcher.Invoke(new Action(ChangeTitle)); Thread.Sleep(1000); // Lambda Dispatcher.Invoke(() => this.Title = "World"); Thread.Sleep(1000); Dispatcher.Invoke(() => this.Title = ""); string newTitle = "Hello World!"; for (int i = 0; i < newTitle.Length; i++) { Thread.Sleep(100); Dispatcher.Invoke(() => this.Title += newTitle[i]); } } public void ChangeTitle() { this.Title = "Hello"; }
- 24. Upda$ng UI and Timer • Timer calls certain method in interval • When using Threading.Timer the task is in different thread – Use Dispatcher.Invoke to manipulate the UI thread • When using Windows.Threading.DispatcherTimer, the task in in UI thread – If this performs a $me consuming task, the UI will freeze
- 25.
- 26. Aync Calls Under .NET 4.5 • Two new keywords to simplify threading even more – async and await • Compiler will generate lot of code when using these keywords • async – Method should be called in an asynchronous manner automa$cally • await – Pause current thread un$l task is complete
- 27. async and await • In .NET 4.5, new keywords: async and await • Simplifies threading, generates a lot of code! • See: – hZp://blogs.msdn.com/b/pfxteam/archive/ 2012/04/12/10293335.aspx
- 28. namespace WpfApplication2 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private async void Button_Click_1(object sender, RoutedEventArgs e) { WebClient wb = new WebClient(); Task<string> result = wb.DownloadStringTaskAsync(new Uri("http://www.tamk.fi/")); string r = await result; Contents.Text = r; } } }
- 29.
- 30. Overview • System.IO namespace provides number of classes for reading and wri$ng • Store and retrieve primi$ve types – BinaryReader, BinaryWriter • Store and retrieve text – StreamReader, StreamWriter • Buffered reading – BufferedStream • Helper classes like File (sta$c), FileInfo (object reference
- 31. Reading and Wri$ng Text • StreamWriter and StreamReader use useful when need for read or write text • By default: Unicode – Can be changed: pass System.TextEncoding object reference • Methods – Write(), WriteLine()
- 32. Wri$ng class SaveText { public static void Main() { StreamWriter writer = File.CreateText("./textfile.txt"); // Nothing happens! Why? writer.WriteLine("Hello World!"); writer.WriteLine("Hello World!"); } }
- 33. Wri$ng: Flush it! using System; using System.IO; class SaveText { public static void Main() { StreamWriter writer = File.CreateText("./textfile.txt"); writer.WriteLine("Hello World!"); writer.WriteLine("Hello World!"); writer.Flush(); } }
- 34. Wri$ng: Stream should be closed! using System; using System.IO; class SaveText { public static void Main() { StreamWriter writer = File.CreateText("./textfile.txt"); writer.WriteLine("Hello World!"); writer.WriteLine("Hello World!"); writer.Flush(); writer.Close(); } }
- 35. Wri$ng: Flushing is done when closing! using System; using System.IO; class SaveText { public static void Main() { StreamWriter writer = File.CreateText("./textfile.txt"); writer.WriteLine("Hello World!"); writer.WriteLine("Hello World!"); writer.Close(); } }
- 36. Wri$ng: using usingSystem; using System.IO; class ReadText { public static void Main() { using( StreamWriter writer = File.CreateText("./textfile.txt") ) { writer.WriteLine("Hello World!"); writer.WriteLine("Hello World!"); } } }
- 37. Reading Text usingSystem; using System.IO; class ReadText { public static void Main() { using( StreamReader reader = File.OpenText("./textfile.txt") ) { string input = null; while((input = reader.ReadLine()) != null) { Console.WriteLine(input); } } } }
- 38. Reading and Wri$ng Binary using System; using System.IO; class ReadBinary { public static void Main() { using( BinaryWriter writer = new BinaryWriter( File.OpenWrite("./test.dat") ) ) { writer.Write(2.2); } using( BinaryReader reader = new BinaryReader( File.OpenRead("./test.dat") ) ) { Console.WriteLine(reader.ReadDouble()); } } }
- 39. Watching Files • Monitor or watch files using FileSystemWatcher class • Really easy to implement – Which folder are we looking? – Set up things to listen – Add Filters – Add Event Handlers – Start listening
- 40. Example using System; usingSystem.IO; class Watcher { public static void Main() { FileSystemWatcher watcher = new FileSystemWatcher(); watcher.Path = "/Users/pohjus/Desktop/tuhoa/"; watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName; watcher.Filter = "*.txt"; watcher.Changed += (object source, FileSystemEventArgs e) => Console.Write("Changed"); watcher.Deleted += (object source, FileSystemEventArgs e) => Console.Write("Deleted"); watcher.EnableRaisingEvents = true; Console.Read(); } }
- 41. Serializable • Serializa$on? Store an state of the object into stream! • Example: Store app preferences into a file. Preference informa$on are stored in object. • How? Mark a class as Serializable and use classes to store and open the object • You can save the object as binary or xml (use XMLSerializer -‐ class)
- 42. using System; using System.IO; using System.Run$me.Serializa$on.FormaZers.Binary; [Serializable] class Person { public string Name { get; set; } public int Age { get; set; } } class SerializableExample { public sta$c void Main() { Person jack = new Person() { Name = "Jack", Age = 20 }; // Let's save jack as binary BinaryFormaZer binFormat = new BinaryFormaZer(); // And in which file? using(FileStream fs = new FileStream("person.dat", FileMode.Create)) { // Let's do it! binFormat.Serialize(fs, jack); } } }
- 43. using System; using System.IO; using System.Run$me.Serializa$on.FormaZers.Binary; [Serializable] class Person { public string Name { get; set; } public int Age { get; set; } } class SerializableExample { public sta$c void Main() { BinaryFormaZer binFormat = new BinaryFormaZer(); // Deserialize! using(FileStream fs = new FileStream("person.dat", FileMode.Open)) { Person jack2 = (Person) binFormat.Deserialize(fs); Console.WriteLine(jack2.Name); Console.WriteLine(jack2.Age); } } }
- 44. ABOUT WIN DESKTOP APPS
- 45. WPF • Windows Presenta$on Founda$on (or WPF) is a computer-‐sogware graphical subsystem for rendering user interfaces in Windows-‐based applica$ons • WPF employs XAML, an XML-‐based language, to define and link various UI elements • See – hZp://msdn.microsog.com/en-‐us/library/ ms752299.aspx