ISourceBlock<TOutput>.ConsumeMessage Method
Definition
Important
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Called by a linked ITargetBlock<TInput> to accept and consume a DataflowMessageHeader previously offered by this ISourceBlock<TOutput>.
public TOutput ConsumeMessage (System.Threading.Tasks.Dataflow.DataflowMessageHeader messageHeader, System.Threading.Tasks.Dataflow.ITargetBlock<out TOutput> target, out bool messageConsumed);public TOutput? ConsumeMessage (System.Threading.Tasks.Dataflow.DataflowMessageHeader messageHeader, System.Threading.Tasks.Dataflow.ITargetBlock<out TOutput> target, out bool messageConsumed);abstract member ConsumeMessage : System.Threading.Tasks.Dataflow.DataflowMessageHeader * System.Threading.Tasks.Dataflow.ITargetBlock<'Output> * bool -> 'OutputPublic Function ConsumeMessage (messageHeader As DataflowMessageHeader, target As ITargetBlock(Of Out TOutput), ByRef messageConsumed As Boolean) As TOutputParameters
- 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
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 OfferMessage(DataflowMessageHeader, TInput, ISourceBlock<TInput>, Boolean).
If the message requested is not available, the return value will be null.
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.
