Microsoft SQL Server Virtual Backup Device Specification
IClientVirtualDevice::GetCommand
| Purpose | This function is used to obtain the next command queued to a device. When requested, this function waits for the next command. | |
| Syntax | HRESULT IClientVirtualDevice::GetCommand (
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| Parameters | Argument | Explanation |
|---|---|---|
| ppCmd | When a command is successfully returned, the parameter returns the address of a command to execute. The memory returned is read-only. When the command is completed, this pointer is passed to the CompleteCommand routine. For more information about each command, see Commands. | |
| dwTimeOut | This is the time to wait, in milliseconds. Use INFINTE to wait indefinitely. Use 0 to poll for a command. VD_E_TIMEOUT is returned if no command is currently available. If the time-out occurs, the client decides the next action. | |
| Return Values | Argument | Explanation |
| NOERROR | A command was fetched. | |
| VD_E_CLOSE | The device has been closed by the server. | |
| VD_E_TIMEOUT | No command was available and the time-out expired. | |
| VD_E_ABORT | Either the client or the server has used the SignalAbort to force a shutdown. | |
| Remarks | When VD_E_CLOSE is returned, SQL Server has closed the device. This is part of the normal shutdown. After all devices have been closed, the client invokes IClientVirtualDeviceSet2::Close to close the virtual device set. When this routine must block to wait for a command, the thread is left in an Alertable condition. |
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