Queue.Synchronized Method

Returns a new Queue that wraps the original queue, and is thread safe.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true)]
public static Queue Synchronized(
	Queue queue
)

Parameters

queue
Type: System.Collections.Queue

The Queue to synchronize.

Return Value

Type: System.Collections.Queue
A Queue wrapper that is synchronized (thread safe).

ExceptionCondition
ArgumentNullException

queue is null.

The wrapper returned by this method locks the queue before an operation is performed so that it is performed in a thread-safe manner.

To guarantee the thread safety of the Queue, all operations must be done through this wrapper only.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration. This method is an O(1) operation.

Queue myCollection = new Queue();
lock(myCollection.SyncRoot)
{
    foreach (object item in myCollection)
    {
        // Insert your code here.
    }
}

The following example shows how to synchronize a Queue, determine if a Queue is synchronized and use a synchronized Queue.

using System;
using System.Collections;
public class SamplesQueue  {

   public static void Main()  {

      // Creates and initializes a new Queue.
      Queue myQ = new Queue();
      myQ.Enqueue( "The" );
      myQ.Enqueue( "quick" );
      myQ.Enqueue( "brown" );
      myQ.Enqueue( "fox" );

      // Creates a synchronized wrapper around the Queue.
      Queue mySyncdQ = Queue.Synchronized( myQ );

      // Displays the sychronization status of both Queues.
      Console.WriteLine( "myQ is {0}.", myQ.IsSynchronized ? "synchronized" : "not synchronized" );
      Console.WriteLine( "mySyncdQ is {0}.", mySyncdQ.IsSynchronized ? "synchronized" : "not synchronized" );
   }
}
/* 
This code produces the following output.

myQ is not synchronized.
mySyncdQ is synchronized.
*/

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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