ConcurrentQueue<T> Class

Definition

generic <typename T>
public ref class ConcurrentQueue : System::Collections::Concurrent::IProducerConsumerCollection<T>, System::Collections::Generic::IEnumerable<T>, System::Collections::Generic::IReadOnlyCollection<T>

[System.Runtime.InteropServices.ComVisible(false)]
[System.Serializable]
public class ConcurrentQueue<T> : System.Collections.Concurrent.IProducerConsumerCollection<T>, System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>

type ConcurrentQueue<'T> = class
    interface IProducerConsumerCollection<'T>
    interface IReadOnlyCollection<'T>
    interface seq<'T>
    interface ICollection
    interface IEnumerable

Public Class ConcurrentQueue(Of T)
Implements IEnumerable(Of T), IProducerConsumerCollection(Of T), IReadOnlyCollection(Of T)

Type Parameters

Inheritance

Object

ConcurrentQueue<T>

Attributes

ComVisibleAttribute SerializableAttribute

Implements

IProducerConsumerCollection<T> IEnumerable<T> IReadOnlyCollection<T> ICollection IEnumerable

Examples

The following example shows how to use a ConcurrentQueue<T> to enqueue and dequeue items:

using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

class CQ_EnqueueDequeuePeek
{
   // Demonstrates:
   // ConcurrentQueue<T>.Enqueue()
   // ConcurrentQueue<T>.TryPeek()
   // ConcurrentQueue<T>.TryDequeue()
   static void Main ()
   {
      // Construct a ConcurrentQueue.
      ConcurrentQueue<int> cq = new ConcurrentQueue<int>();

      // Populate the queue.
      for (int i = 0; i < 10000; i++)
      {
          cq.Enqueue(i);
      }

      // Peek at the first element.
      int result;
      if (!cq.TryPeek(out result))
      {
         Console.WriteLine("CQ: TryPeek failed when it should have succeeded");
      }
      else if (result != 0)
      {
         Console.WriteLine("CQ: Expected TryPeek result of 0, got {0}", result);
      }

      int outerSum = 0;
      // An action to consume the ConcurrentQueue.
      Action action = () =>
      {                
         int localSum = 0;
         int localValue;
         while (cq.TryDequeue(out localValue)) localSum += localValue;
         Interlocked.Add(ref outerSum, localSum);
      };

      // Start 4 concurrent consuming actions.
      Parallel.Invoke(action, action, action, action);

      Console.WriteLine("outerSum = {0}, should be 49995000", outerSum);
   }
}

Imports System.Collections.Concurrent
Imports System.Threading
Imports System.Threading.Tasks

Class TestQueue
   ' Demonstrates:
   ' ConcurrentQueue<T>.Enqueue()
   ' ConcurrentQueue<T>.TryPeek()
   ' ConcurrentQueue<T>.TryDequeue()
   Shared Sub Main()
      ' Construct a ConcurrentQueue
      Dim cq As New ConcurrentQueue(Of Integer)()

      ' Populate the queue
      For i As Integer = 0 To 9999
         cq.Enqueue(i)
      Next

      ' Peek at the first element
      Dim result As Integer
      If Not cq.TryPeek(result) Then
         Console.WriteLine("CQ: TryPeek failed when it should have succeeded")
      ElseIf result <> 0 Then
         Console.WriteLine("CQ: Expected TryPeek result of 0, got {0}", result)
      End If

      Dim outerSum As Integer = 0

      ' An action to consume the ConcurrentQueue
      Dim action As Action =
          Sub()
             Dim localSum As Integer = 0
             Dim localValue As Integer
             While cq.TryDequeue(localValue)
                localSum += localValue
             End While
             Interlocked.Add(outerSum, localSum)
          End Sub

      ' Start 4 concurrent consuming actions
      Parallel.Invoke(action, action, action, action)

      Console.WriteLine("outerSum = {0}, should be 49995000", outerSum)
   End Sub
End Class

Remarks

Constructors

Properties

Methods

Explicit Interface Implementations

Extension Methods

Applies to

Thread Safety

All public and protected members of ConcurrentQueue<T> are thread-safe and may be used concurrently from multiple threads.