TransformBlock<TInput,TOutput>.ISourceBlock<TOutput>.ConsumeMessage(DataflowMessageHeader, ITargetBlock<TOutput>, Boolean) Method

Definition

Called by a linked ITargetBlock<TInput> to accept and consume a DataflowMessageHeader previously offered by this ISourceBlock<TOutput>.

 virtual TOutput System.Threading.Tasks.Dataflow.ISourceBlock<TOutput>.ConsumeMessage(System::Threading::Tasks::Dataflow::DataflowMessageHeader messageHeader, System::Threading::Tasks::Dataflow::ITargetBlock<TOutput> ^ target, [Runtime::InteropServices::Out] bool % messageConsumed) = System::Threading::Tasks::Dataflow::ISourceBlock<TOutput>::ConsumeMessage;
TOutput ISourceBlock<TOutput>.ConsumeMessage (System.Threading.Tasks.Dataflow.DataflowMessageHeader messageHeader, System.Threading.Tasks.Dataflow.ITargetBlock<TOutput> target, out bool messageConsumed);
Function ConsumeMessage (messageHeader As DataflowMessageHeader, target As ITargetBlock(Of TOutput), ByRef messageConsumed As Boolean) As TOutput Implements ISourceBlock(Of TOutput).ConsumeMessage

Parameters

messageHeader
DataflowMessageHeader

The DataflowMessageHeader of the message being consumed.

target
ITargetBlock<TOutput>

The ITargetBlock<TInput> consuming the message.

messageConsumed
Boolean

true if the message was successfully consumed; otherwise, false.

Returns

TOutput

The value of the consumed message. This may correspond to a different DataflowMessageHeader instance than was previously reserved and passed as the messageHeader to ConsumeMessage(DataflowMessageHeader, ITargetBlock<TOutput>, Boolean). The consuming ITargetBlock<TInput> must use the returned value instead of the value passed as messageValue through ITargetBlock<TInput>.OfferMessage(DataflowMessageHeader, TInput, ISourceBlock<TInput>, Boolean).

If the message requested is not available, the return value will be null.

Implements

Exceptions

The messageHeader is not valid.

The target is null.

Remarks

Only ITargetBlock<TInput> instances linked to this ISourceBlock<TOutput> instance may use ConsumeMessage, and it must only be used to consume DataflowMessageHeader instances previously offered by this source to the target.

Applies to