WdfIoQueueRetrieveNextRequest function

[Applies to KMDF and UMDF]

The WdfIoQueueRetrieveNextRequest method retrieves the next available I/O request from a specified I/O queue.

Syntax

NTSTATUS WdfIoQueueRetrieveNextRequest(
  WDFQUEUE   Queue,
  WDFREQUEST *OutRequest
);

Parameters

Queue

A handle to a framework queue object.

OutRequest

A pointer to a location that receives a handle to a framework request object. If the queue is empty or the last request has been retrieved, this parameter receives NULL.

Return value

WdfIoQueueRetrieveNextRequest returns STATUS_SUCCESS if the operation succeeds. Otherwise, this method might return one of the following values:

Return code Description
STATUS_INVALID_PARAMETER
The driver supplied an invalid handle.
STATUS_NO_MORE_ENTRIES
The framework reached the end of the I/O queue.
STATUS_INVALID_DEVICE_STATE
The specified I/O queue is configured for the parallel dispatching method.
STATUS_WDF_PAUSED
The specified I/O queue is power-managed and its device is in a low-power state, or the specified queue is stopped.
 

This method also might return other NTSTATUS values.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

If a driver configures an I/O queue for manual dispatching of I/O requests, the driver typically calls WdfIoQueueRetrieveNextRequest to obtain requests from the queue. A driver that has configured an I/O queue for sequential dispatching might also call WdfIoQueueRetrieveNextRequest. For more information about using WdfIoQueueRetrieveNextRequest with the manual or sequential dispatching methods, see Dispatching Methods for I/O Requests.

After calling WdfIoQueueRetrieveNextRequest to obtain an I/O request, the driver owns the request and must process the I/O request in some manner.

For more information about the WdfIoQueueRetrieveNextRequest method, see Managing I/O Queues.

Examples

The following code example obtains a handle to the next request object that is contained in a device's I/O queue.

NTSTATUS  status;
WDFREQUEST  request;

status = WdfIoQueueRetrieveNextRequest(
                                       pDeviceContext->ReadQueue,
                                       &request
                                       );

Requirements

   
Target Platform Universal
Minimum KMDF version 1.0
Minimum UMDF version 2.0
Header wdfio.h (include Wdf.h)
Library Wdf01000.sys (KMDF); WUDFx02000.dll (UMDF)
IRQL <= DISPATCH_LEVEL
DDI compliance rules DoubleCompletion, DriverCreate, KmdfIrql, KmdfIrql2, wdfioqueueretrievenextrequest

See also

WdfIoQueueRetrieveFoundRequest

WdfIoQueueRetrieveRequestByFileObject