helpful classes

2016. 11. 24. 02:29

helpful classes 프로그래밍/C#2016. 11. 24. 02:29

Dispatcher Class
Thread Class
ThreadPool Class
WebClient Class
GC Class

Dispatcher Class

https://msdn.microsoft.com/en-us/library/system.windows.threading.dispatcher(v=vs.110).aspx

Provides services for managing the queue of work items for a thread.

Namespace: System.Windows.Threading
Assembly: WindowsBase (in WindowsBase.dll)

Inheritance Hierarchy

System.Object
System.Windows.Threading.Dispatcher

Remarks

The Dispatcher maintains a prioritized queue of work items for a specific thread.

When a Dispatcher is created on a thread, it becomes the only Dispatcher that can be associated with the thread, even if the Dispatcher is shut down.

If you attempt to get the CurrentDispatcher for the current thread and a Dispatcher is not associated with the thread, a Dispatcher will be created. A Dispatcher is also created when you create a DispatcherObject. If you create a Dispatcher on a background thread, be sure to shut down the dispatcher before exiting the thread.

If a Dispatcher is shut down, it cannot be restarted.

In WPF, a DispatcherObject can only be accessed by the Dispatcher it is associated with. For example, a background thread cannot update the contents of a Button that is associated with the Dispatcher on the UI thread. In order for the background thread to access the Content property of the Button, the background thread must delegate the work to the Dispatcher associated with the UI thread. This is accomplished by using either Invoke or BeginInvoke. Invoke is synchronous and BeginInvoke is asynchronous. The operation is added to the queue of the Dispatcher at the specified DispatcherPriority.

If BeginInvoke is called on a Dispatcher that has shut down, the status property of the returned DispatcherOperation is set to Aborted.

All of the methods on Dispatcher, with the exception of DisableProcessing, are free-threaded.

Objects that derive from DispatcherObject have thread affinity.

Objects that derive from Freezable are free-threaded when they are frozen. For more information, see Freezable Objects Overview.

Examples

The following example shows how to place an operation onto a Dispatcher. For the full source code of this example, see Single-Threaded Application with Long-Running Calculation Sample.

First, a delegate is created that accepts no arguments.

public delegate void NextPrimeDelegate();

Next, BeginInvoke(DispatcherPriority, Delegate) is called. This call to BeginInvoke(DispatcherPriority, Delegate) takes two parameters: the priority, which is set to DispatcherPriority.Normal, and the callback, which is passed in through an instance of the delegate NextPrimeDelegate.

startStopButton.Dispatcher.BeginInvoke(
    DispatcherPriority.Normal,
    new NextPrimeDelegate(CheckNextNumber));

Thread Class

https://msdn.microsoft.com/en-us/library/system.threading.thread(v=vs.110).aspx

Creates and controls a thread, sets its priority, and gets its status.

Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)

Inheritance Hierarchy

System.Object
System.Runtime.ConstrainedExecution.CriticalFinalizerObject
System.Threading.Thread

Remarks

When a process starts, the common language runtime automatically creates a single foreground thread to execute application code. Along with this main foreground thread, a process can create one or more threads to execute a portion of the program code associated with the process. These threads can execute either in the foreground or in the background. In addition, you can use the ThreadPool class to execute code on worker threads that are managed by the common language runtime.

In this section

Starting a thread
Retrieving Thread objects
Foreground and background threads
Culture and threads
Getting information about and controlling threads
Accessing the source code for the Thread class

Starting a thread

You start a thread by supplying a delegate that represents the method the thread is to execute in its class constructor. You then call the Startmethod to begin execution.

The Thread constructors can take either of two delegate types, depending on whether you can pass an argument to the method to be executed:

If the method has no arguments, you pass a ThreadStart delegate to the constructor. It has the signature:

public delegate void ThreadStart()

The following example creates and starts a thread that executes the ExecuteInForeground method. The method displays information about some thread properties, then executes a loop in which it pauses for half a second and displays the elapsed number of seconds. When the thread has executed for at least five seconds, the loop ends and the thread terminates execution.

using System;
using System.Diagnostics;
using System.Threading;

public class Example
{
   public static void Main()
   {
      var th = new Thread(ExecuteInForeground);
      th.Start();
      Thread.Sleep(1000);
      Console.WriteLine("Main thread ({0}) exiting...", 
                        Thread.CurrentThread.ManagedThreadId); 
   }

   private static void ExecuteInForeground()
   {
      DateTime start = DateTime.Now;
      var sw = Stopwatch.StartNew();
      Console.WriteLine("Thread {0}: {1}, Priority {2}", 
                        Thread.CurrentThread.ManagedThreadId,
                        Thread.CurrentThread.ThreadState,
                        Thread.CurrentThread.Priority);
      do { 
         Console.WriteLine("Thread {0}: Elapsed {1:N2} seconds", 
                           Thread.CurrentThread.ManagedThreadId,
                           sw.ElapsedMilliseconds / 1000.0);
         Thread.Sleep(500);
      } while (sw.ElapsedMilliseconds <= 5000);
      sw.Stop(); 
   }
}
// The example displays output like the following:
//       Thread 3: Running, Priority Normal
//       Thread 3: Elapsed 0.00 seconds
//       Thread 3: Elapsed 0.51 seconds
//       Main thread (1) exiting...
//       Thread 3: Elapsed 1.02 seconds
//       Thread 3: Elapsed 1.53 seconds
//       Thread 3: Elapsed 2.05 seconds
//       Thread 3: Elapsed 2.55 seconds
//       Thread 3: Elapsed 3.07 seconds
//       Thread 3: Elapsed 3.57 seconds
//       Thread 3: Elapsed 4.07 seconds
//       Thread 3: Elapsed 4.58 seconds

If the method has an argument, you pass a ParameterizedThreadStart delegate to the constructor. It has the signature:

public delegate void ParameterizedThreadStart(object obj)

The method executed by the delegate can then cast (in C#) or convert (in Visual Basic) the parameter to the appropriate type.

The following example is identical to the previous one, except that it calls the Thread(ParameterizedThreadStart) constructor. This version of the ExecuteInForeground method has a single parameter that represents the approximate number of milliseconds the loop is to execute.

using System;
using System.Diagnostics;
using System.Threading;

public class Example
{
   public static void Main()
   {
      var th = new Thread(ExecuteInForeground);
      th.Start(4500);
      Thread.Sleep(1000);
      Console.WriteLine("Main thread ({0}) exiting...", 
                        Thread.CurrentThread.ManagedThreadId); 
   }

   private static void ExecuteInForeground(Object obj)
   {
      int interval;
      try {
         interval = (int) obj;
      }
      catch (InvalidCastException) {
         interval = 5000;
      }
      DateTime start = DateTime.Now;
      var sw = Stopwatch.StartNew();
      Console.WriteLine("Thread {0}: {1}, Priority {2}", 
                        Thread.CurrentThread.ManagedThreadId,
                        Thread.CurrentThread.ThreadState,
                        Thread.CurrentThread.Priority);
      do { 
         Console.WriteLine("Thread {0}: Elapsed {1:N2} seconds", 
                           Thread.CurrentThread.ManagedThreadId,
                           sw.ElapsedMilliseconds / 1000.0);
         Thread.Sleep(500);
      } while (sw.ElapsedMilliseconds <= interval);
      sw.Stop(); 
   }
}
// The example displays output like the following:
//       Thread 3: Running, Priority Normal
//       Thread 3: Elapsed 0.00 seconds
//       Thread 3: Elapsed 0.52 seconds
//       Main thread (1) exiting...
//       Thread 3: Elapsed 1.03 seconds
//       Thread 3: Elapsed 1.55 seconds
//       Thread 3: Elapsed 2.06 seconds
//       Thread 3: Elapsed 2.58 seconds
//       Thread 3: Elapsed 3.09 seconds
//       Thread 3: Elapsed 3.61 seconds
//       Thread 3: Elapsed 4.12 seconds

It is not necessary to retain a reference to a Thread object once you have started the thread. The thread continues to execute until the thread procedure is complete.

Retrieving Thread objects

You can use the static (Shared in Visual Basic) CurrentThread property to retrieve a reference to the currently executing thread from the code that the thread is executing. The following example uses the CurrentThread property to display information about the main application thread, another foreground thread, a background thread, and a thread pool thread.

using System;
using System.Threading;

public class Example
{
   static Object obj = new Object();

   public static void Main()
   {
      ThreadPool.QueueUserWorkItem(ShowThreadInformation);
      var th1 = new Thread(ShowThreadInformation);
      th1.Start();
      var th2 = new Thread(ShowThreadInformation);
      th2.IsBackground = true;
      th2.Start();
      Thread.Sleep(500);
      ShowThreadInformation(null); 
   }

   private static void ShowThreadInformation(Object state)
   {
      lock (obj) {
         var th  = Thread.CurrentThread;
         Console.WriteLine("Managed thread #{0}: ", th.ManagedThreadId);
         Console.WriteLine("   Background thread: {0}", th.IsBackground);
         Console.WriteLine("   Thread pool thread: {0}", th.IsThreadPoolThread);
         Console.WriteLine("   Priority: {0}", th.Priority);
         Console.WriteLine("   Culture: {0}", th.CurrentCulture.Name);
         Console.WriteLine("   UI culture: {0}", th.CurrentUICulture.Name);
         Console.WriteLine();
      }   
   }
}
// The example displays output like the following:
//       Managed thread #6:
//          Background thread: True
//          Thread pool thread: False
//          Priority: Normal
//          Culture: en-US
//          UI culture: en-US
//       
//       Managed thread #3:
//          Background thread: True
//          Thread pool thread: True
//          Priority: Normal
//          Culture: en-US
//          UI culture: en-US
//       
//       Managed thread #4:
//          Background thread: False
//          Thread pool thread: False
//          Priority: Normal
//          Culture: en-US
//          UI culture: en-US
//       
//       Managed thread #1:
//          Background thread: False
//          Thread pool thread: False
//          Priority: Normal
//          Culture: en-US
//          UI culture: en-US

Foreground and background threads

Instances of the Thread class represent either foreground threads or background threads. Background threads are identical to foreground threads with one exception: a background thread does not keep a process running if all foreground threads have terminated. Once all foreground threads have been stopped, the runtime stops all background threads and shuts down.

By default, the following threads execute in the foreground:

The main application thread.
All threads created by calling a Thread class constructor.

The following threads execute in the background by default:

Thread pool threads, which are a pool of worker threads maintained by the runtime. You can configure the thread pool and schedule work on thread pool threads by using the ThreadPool class.

Note
Task-based asynchronous operations automatically execute on thread pool threads. Task-based asynchronous operations use the Taskand Task<TResult> classes to implement the task-based asynchronous pattern.

All threads that enter the managed execution environment from unmanaged code.

You can change a thread to execute in the background by setting the IsBackground property at any time. Background threads are useful for any operation that should continue as long as an application is running but should not prevent the application from terminating, such as monitoring file system changes or incoming socket connections.

The following example illustrates the difference between foreground and background threads. It is like the first example in the Starting a threadsection, except that it sets the thread to execute in the background before starting it. As the output shows, the loop is interrupted before it executes for five seconds.

using System;
using System.Diagnostics;
using System.Threading;

public class Example
{
   public static void Main()
   {
      var th = new Thread(ExecuteInForeground);
      th.IsBackground = true;
      th.Start();
      Thread.Sleep(1000);
      Console.WriteLine("Main thread ({0}) exiting...", 
                        Thread.CurrentThread.ManagedThreadId); 
   }

   private static void ExecuteInForeground()
   {
      DateTime start = DateTime.Now;
      var sw = Stopwatch.StartNew();
      Console.WriteLine("Thread {0}: {1}, Priority {2}", 
                        Thread.CurrentThread.ManagedThreadId,
                        Thread.CurrentThread.ThreadState,
                        Thread.CurrentThread.Priority);
      do { 
         Console.WriteLine("Thread {0}: Elapsed {1:N2} seconds", 
                           Thread.CurrentThread.ManagedThreadId,
                           sw.ElapsedMilliseconds / 1000.0);
         Thread.Sleep(500);
      } while (sw.ElapsedMilliseconds <= 5000);
      sw.Stop(); 
   }
}
// The example displays output like the following:
//       Thread 3: Background, Priority Normal
//       Thread 3: Elapsed 0.00 seconds
//       Thread 3: Elapsed 0.51 seconds
//       Main thread (1) exiting...

Culture and threads

Each thread has a culture, represented by the CurrentCulture property, and a UI culture, represented by the CurrentUICulture property. The current culture supports such culture-sensitive operations as parsing and formatting, string comparison and sorting, and also controls the writing system and calendar used by a thread. The current UI culture provides for culture-sensitive retrieval of resources in resource files.

When a new thread is instantiated, its culture and UI culture are defined by the current system culture and UI culture, and not by the culture and UI culture of the thread from which the new thread is created. This means, for example, that if the current system culture is English (United States) and the current culture of the primary application thread is French (France), the culture of a new thread created by calling theThread(ParameterizedThreadStart) constructor from the primary thread is English (United States), and not French (France). For more information, see the "Culture and threads" section of the CultureInfo class topic.

Important
This is not true of threads that execute asynchronous operations for apps that target the .NET Framework 4.6 and later versions, In this case, the culture and UI culture is part of an asynchronous operations' context; the thread on which an asynchronous operation executes by default inherits the culture and UI culture of the thread from which the asynchronous operation was launched. For more information, see the "Culture and task-based asynchronous operations" section of the CultureInfo class topic.

Important

This is not true of threads that execute asynchronous operations for apps that target the .NET Framework 4.6 and later versions, In this case, the culture and UI culture is part of an asynchronous operations' context; the thread on which an asynchronous operation executes by default inherits the culture and UI culture of the thread from which the asynchronous operation was launched. For more information, see the "Culture and task-based asynchronous operations" section of the CultureInfo class topic.

You can do either of the following to ensure that all of the threads executing in an application share the same culture and UI culture:

You can pass a CultureInfo object that represents that culture to the ParameterizedThreadStart delegate or the ThreadPool.QueueUserWorkItem(WaitCallback, Object) method.
For apps running on the .NET Framework 4.5 and later versions, you can define the culture and UI culture that is to be assigned to all threads created in an application domain by setting the value of the CultureInfo.DefaultThreadCurrentCulture and CultureInfo.DefaultThreadCurrentUICulture properties. Note that this is a per-application domain setting.

For more information and examples, see the "Culture and threads" section of the CultureInfo class topic.

Getting information about and controlling threads

You can retrieve a number of property values that provide information about a thread. In some cases, you can also set these property values to control the operation of the thread. These thread properties include:

A name. Name is a write-once property that you can use to identify a thread. Its default value is null.
A hash code, which you can retrieve by calling the GetHashCode method. The hash code can be used to uniquely identify a thread; for the lifetime of your thread, its hash code will not collide with the value from any other thread, regardless of the application domain from which you obtain the value.

A thread ID. The value of the read-only ManagedThreadId property is assigned by the runtime and uniquely identifies a thread within its process.

Note
An operating-system ThreadId has no fixed relationship to a managed thread, because an unmanaged host can control the relationship between managed and unmanaged threads. Specifically, a sophisticated host can use the CLR Hosting API to schedule many managed threads against the same operating system thread, or to move a managed thread between different operating system threads.

The thread's current state. For the duration of its existence, a thread is always in one or more of the states defined by the ThreadStateproperty.
A scheduling priority level, which is defined by the ThreadPriority property. Although you can set this value to request a thread's priority, it is not guaranteed to be honored by the operating system.
The read-only IsThreadPoolThread property, which indicates whether a thread is a thread pool thread.
The IsBackground property. For more information, see the Foreground and background threads section.

Accessing the source code for the Thread class

To view the .NET Framework source code for the Thread class, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

Examples

The following example demonstrates simple threading functionality.

Exception	Condition
ArgumentNullException	callBack is null.
NotSupportedException	The common language runtime (CLR) is hosted, and the host does not support this action.

Method	Description
OpenWrite	Retrieves a Stream used to send data to the resource.
OpenWriteAsync	Retrieves a Stream used to send data to the resource, without blocking the calling thread.
UploadData	Sends a byte array to the resource and returns a Byte array containing any response.
UploadDataAsync	Sends a Byte array to the resource, without blocking the calling thread.
UploadFile	Sends a local file to the resource and returns a Byte array containing any response.
UploadFileAsync	Sends a local file to the resource, without blocking the calling thread.
UploadValues	Sends a NameValueCollection to the resource and returns a Byte array containing any response.
UploadValuesAsync	Sends a NameValueCollection to the resource and returns a Byte array containing any response, without blocking the calling thread.
UploadString	Sends a String to the resource, without blocking the calling thread.
UploadStringAsync	Sends a String to the resource, without blocking the calling thread.

Method	Description
OpenRead	Returns the data from a resource as a Stream.
OpenReadAsync	Returns the data from a resource, without blocking the calling thread.
DownloadData	Downloads data from a resource and returns a Byte array.
DownloadDataAsync	Downloads data from a resource and returns a Byte array, without blocking the calling thread.
DownloadFile	Downloads data from a resource to a local file.
DownloadFileAsync	Downloads data from a resource to a local file, without blocking the calling thread.
DownloadString	Downloads a String from a resource and returns a String.
DownloadStringAsync	Downloads a String from a resource, without blocking the calling thread.

클래스 종류 헤드라인 (0)	2017.01.04
C# Keywords - Types (0)	2016.12.29
Operators (0)	2016.11.14
IEnumerable Interface (0)	2016.11.14
Predicate<T> Delegate (0)	2016.10.18

달력

helpful classes 프로그래밍/C#2016. 11. 24. 02:29

Parameters

Parameters

Parameters

Return Value

Parameters

Return Value

Notes to Inheritors:

Parameters

Parameters

Return Value

'프로그래밍 > C#' 카테고리의 다른 글

카테고리

공지사항

태그목록

최근에 올라온 글

최근에 달린 댓글

최근에 받은 트랙백

글 보관함

링크

티스토리툴바