ISourceBlock<TOutput>.ReserveMessage Method
Definition
Important
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Called by a linked ITargetBlock<TInput> to reserve a previously offered DataflowMessageHeader by this ISourceBlock<TOutput>.
public:
bool ReserveMessage(System::Threading::Tasks::Dataflow::DataflowMessageHeader messageHeader, System::Threading::Tasks::Dataflow::ITargetBlock<TOutput> ^ target);public bool ReserveMessage (System.Threading.Tasks.Dataflow.DataflowMessageHeader messageHeader, System.Threading.Tasks.Dataflow.ITargetBlock<out TOutput> target);abstract member ReserveMessage : System.Threading.Tasks.Dataflow.DataflowMessageHeader * System.Threading.Tasks.Dataflow.ITargetBlock<'Output> -> boolPublic Function ReserveMessage (messageHeader As DataflowMessageHeader, target As ITargetBlock(Of Out TOutput)) As BooleanParameters
- messageHeader
- DataflowMessageHeader
The DataflowMessageHeader of the message being reserved.
- target
- ITargetBlock<TOutput>
The ITargetBlock<TInput> reserving the message.
Returns
true if the message was successfully reserved; otherwise, false.
Exceptions
The messageHeader is not valid.
The target is null.
Remarks
Only ITargetBlock<TInput> instances linked to this ISourceBlock<TOutput> instance may use ReserveMessage, and it must only be used to reserve DataflowMessageHeader instances previously offered by this source to the target.
If true is returned, the ITargetBlock<TInput> must subsequently call either ConsumeMessage or ReleaseReservation for this message. Failure to do so may result in the source being unable to propagate any further messages to this or other targets.
ReserveMessage must not be called while the target is holding any internal locks. Doing so will violate the lock hierarchy necessary to avoid deadlocks in a dataflow network.
