/// <summary>
/// Called when the scan attributes timer expires.
/// </summary>
private void DoScan(Dictionary <string, HdaSubscribeAttributeRequest> requests, bool initialUpdate)
{
try
{
ComHdaClientManager system = (ComHdaClientManager)m_context.SystemHandle;
ComHdaClient client = (ComHdaClient)system.SelectClient(m_context, false);
// ensure all requests have valid handles.
AssignHandles(client, requests);
// collect the list of attributes that need reading.
HdaReadRequestCollection itemsToRead = new HdaReadRequestCollection();
List <HdaSubscribeAttributeRequest> subscribeRequests = new List <HdaSubscribeAttributeRequest>();
List <HdaReadRequest> readRequestsForSubscribeRequests = new List <HdaReadRequest>();
lock (m_lock)
{
DateTime now = DateTime.UtcNow;
foreach (KeyValuePair <string, HdaSubscribeAttributeRequest> entry in requests)
{
// check if it is time for an update.
if (!initialUpdate && entry.Value.NextUpdateTime > now)
{
continue;
}
// create a read request for each monitored item.
bool somethingToDo = false;
for (int ii = 0; ii < entry.Value.MonitoredItems.Count; ii++)
{
MonitoredItem monitoredItem = entry.Value.MonitoredItems[ii];
NodeHandle handle = monitoredItem.ManagerHandle as NodeHandle;
if (handle == null)
{
continue;
}
// check if item is not valid.
if (entry.Value.ServerHandle == null)
{
monitoredItem.QueueValue(null, StatusCodes.BadNodeIdUnknown);
continue;
}
ReadValueId valueToRead = monitoredItem.GetReadValueId();
bool queued = false;
StatusCode error = itemsToRead.Add(handle.Node, valueToRead, out queued);
if (StatusCode.IsBad(error))
{
monitoredItem.QueueValue(null, error);
continue;
}
if (!somethingToDo && queued)
{
// add server handle to read request.
HdaReadRequest request = (HdaReadRequest)valueToRead.Handle;
request.ServerHandle = entry.Value.ServerHandle.Value;
// save mapping between subscribe request and read requests.
subscribeRequests.Add(entry.Value);
readRequestsForSubscribeRequests.Add(request);
somethingToDo = true;
}
}
}
// check if nothing to do.
if (requests.Count == 0)
{
return;
}
}
// read the attributes from the server.
client.Read(itemsToRead, true);
// update the monitored items.
lock (m_lock)
{
for (int ii = 0; ii < subscribeRequests.Count; ii++)
{
subscribeRequests[ii].QueueValues(m_context, readRequestsForSubscribeRequests[ii], initialUpdate);
}
}
}
catch (Exception e)
{
Utils.Trace(e, "Unexpected error scanning attributes in HDA COM server.");
}
}
