BlockingCollection<T>.GetConsumingEnumerable Method

Definition

Namespace:

System.Collections.Concurrent

Assembly:

System.Collections.Concurrent.dll

Provides a consuming IEnumerable<T> for items in the collection.

Overloads

GetConsumingEnumerable(CancellationToken)	Provides a consuming IEnumerable<T> for items in the collection.
GetConsumingEnumerable()	Provides a consuming IEnumerable<T> for items in the collection.

GetConsumingEnumerable(CancellationToken)

Source:

BlockingCollection.cs

Provides a consuming IEnumerable<T> for items in the collection.

public:
 System::Collections::Generic::IEnumerable<T> ^ GetConsumingEnumerable(System::Threading::CancellationToken cancellationToken);

public System.Collections.Generic.IEnumerable<T> GetConsumingEnumerable (System.Threading.CancellationToken cancellationToken);

member this.GetConsumingEnumerable : System.Threading.CancellationToken -> seq<'T>

Public Function GetConsumingEnumerable (cancellationToken As CancellationToken) As IEnumerable(Of T)

Parameters

cancellationToken

CancellationToken

A cancellation token to observe.

Returns

IEnumerable<T>

An IEnumerable<T> that removes and returns items from the collection.

Exceptions

OperationCanceledException

The CancellationToken is canceled.

ObjectDisposedException

The BlockingCollection<T> has been disposed or the CancellationTokenSource that created cancellationToken has been disposed

Remarks

This method enables client code to remove items from the collection by using a foreach loop (For Each in Visual Basic), or Parallel.ForEach or a PLINQ query. The enumerator will continue to provide items (if any exist) until IsCompleted returns true, and if IsCompleted is false the loop blocks until an item becomes available or until the CancellationToken is cancelled.

See also

• Thread-Safe Collections
• BlockingCollection Overview

GetConsumingEnumerable()

Source:

BlockingCollection.cs

Provides a consuming IEnumerable<T> for items in the collection.

public:
 System::Collections::Generic::IEnumerable<T> ^ GetConsumingEnumerable();

public System.Collections.Generic.IEnumerable<T> GetConsumingEnumerable ();

member this.GetConsumingEnumerable : unit -> seq<'T>

Public Function GetConsumingEnumerable () As IEnumerable(Of T)

Returns

IEnumerable<T>

An IEnumerable<T> that removes and returns items from the collection.

Exceptions

ObjectDisposedException

The BlockingCollection<T> has been disposed.

Examples

The following example shows how to use the GetConsumingEnumerable method:

class ConsumingEnumerableDemo
{
    // Demonstrates:
    //      BlockingCollection<T>.Add()
    //      BlockingCollection<T>.CompleteAdding()
    //      BlockingCollection<T>.GetConsumingEnumerable()
    public static async Task BC_GetConsumingEnumerable()
    {
        using (BlockingCollection<int> bc = new BlockingCollection<int>())
        {
            // Kick off a producer task
            var producerTask = Task.Run(async () =>
            {
                for (int i = 0; i < 10; i++)
                {
                    bc.Add(i);
                    Console.WriteLine($"Producing: {i}");

                    await Task.Delay(100); // sleep 100 ms between adds
                }

                // Need to do this to keep foreach below from hanging
                bc.CompleteAdding();
            });

            // Now consume the blocking collection with foreach.
            // Use bc.GetConsumingEnumerable() instead of just bc because the
            // former will block waiting for completion and the latter will
            // simply take a snapshot of the current state of the underlying collection.
            foreach (var item in bc.GetConsumingEnumerable())
            {
                Console.WriteLine($"Consuming: {item}");
            }
            await producerTask; // Allow task to complete cleanup
        }
    }
}

module ConsumingEnumerableDemo =
    // Demonstrates:
    //      BlockingCollection<T>.Add()
    //      BlockingCollection<T>.CompleteAdding()
    //      BlockingCollection<T>.GetConsumingEnumerable()
    let blockingCollectionGetConsumingEnumerable () =
        task {
            use bc = new BlockingCollection<int>()
            // Kick off a producer task
            let producerTask =
                task {
                    for i = 0 to 9 do
                        bc.Add i
                        printfn $"Producing: {i}"

                        do! Task.Delay 100 // sleep 100 ms between adds
                    // Need to do this to keep foreach below from hanging
                    bc.CompleteAdding()
                }

            // Now consume the blocking collection with foreach.
            // Use bc.GetConsumingEnumerable() instead of just bc because the
            // former will block waiting for completion and the latter will
            // simply take a snapshot of the current state of the underlying collection.
            for item in bc.GetConsumingEnumerable() do
                printfn $"Consuming: {item}"
            do! producerTask // Allow task to complete cleanup
        }

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

' Demonstrates:
' BlockingCollection<T>.Add()
' BlockingCollection<T>.CompleteAdding()
' BlockingCollection<T>.GetConsumingEnumerable()

Class ConsumingEnumerableDemo
    Shared Sub BC_GetConsumingEnumerable()
        Using bc As New BlockingCollection(Of Integer)()

            ' Kick off a producer task
            Task.Factory.StartNew(
                Sub()
                    For i As Integer = 0 To 9
                        bc.Add(i)
                        ' sleep 100 ms between adds
                        Thread.Sleep(100)
                    Next

                    ' Need to do this to keep foreach below from not responding.
                    bc.CompleteAdding()
                End Sub)
            ' Now consume the blocking collection with foreach.
            ' Use bc.GetConsumingEnumerable() instead of just bc because the
            ' former will block waiting for completion and the latter will
            ' simply take a snapshot of the current state of the underlying collection.
            For Each item In bc.GetConsumingEnumerable()
                Console.WriteLine(item)
            Next
        End Using
    End Sub
End Class

See also

• Thread-Safe Collections
• BlockingCollection Overview