public async Task MonitoredIoTCEventsProcessorAsync()
{
DateTime nextSendTime = DateTime.UtcNow + TimeSpan.FromSeconds(_timeout);
double millisecondsTillNextSend = nextSendTime.Subtract(DateTime.UtcNow).TotalMilliseconds;
EventMessageData eventMessageData = null;
while (!_shutdownToken.IsCancellationRequested)
{
try
{
// sanity check the send interval, compute the timeout and get the next monitored item message
if (_timeout > 0)
{
millisecondsTillNextSend = nextSendTime.Subtract(DateTime.UtcNow).TotalMilliseconds;
if (millisecondsTillNextSend < 0)
{
// do not wait if we missed the send interval
millisecondsTillNextSend = 0;
}
}
else
{
// if we are in shutdown do not wait, else wait infinite if send interval is not set
millisecondsTillNextSend = _shutdownToken.IsCancellationRequested ? 0 : Timeout.Infinite;
}
var gotItem = _monitoredIoTcEventDataQueue.TryTake(out MessageData messageData, (int)millisecondsTillNextSend, _shutdownToken);
// the two commandline parameter --ms (message size) and --si (send interval) control when data is sent to IoTHub/EdgeHub
// pls see detailed comments on performance and memory consumption at https://github.com/Azure/iot-edge-opc-publisher
// check if we got an item or if we hit the timeout or got canceled
if (gotItem)
{
eventMessageData = messageData?.EventMessageData;
if (eventMessageData != null)
{
// for IoTCentral we send simple key/value pairs. key is the DisplayName, value the value.
_jsonMessage = await CreateIoTCentralJsonForEventChangeAsync(eventMessageData, _shutdownToken).ConfigureAwait(false);
_jsonMessageSize =
Encoding.UTF8.GetByteCount(_jsonMessage.ToString(CultureInfo.InvariantCulture));
// sanity check that the user has set a large enough messages size
if ((_hubMessageSize > 0 && _jsonMessageSize > _hubMessageSize) ||
(_hubMessageSize == 0 && _jsonMessageSize > _hubMessageBufferSize))
{
_logger.Error(
$"There is a IoT Central event message (size: {_jsonMessageSize}), which will not fit into an hub message (max size: {_hubMessageBufferSize}].");
_logger.Error(
$"Please check your hub message size settings. The IoT Central event message will be discarded silently. Sorry:(");
TooLargeCount++;
continue;
}
// if batching is requested or we need to send at intervals, batch it otherwise send it right away
_needToBufferMessage = false;
if (_hubMessageSize > 0 || (_hubMessageSize == 0 && _timeout > 0))
{
// if there is still space to batch, do it. otherwise send the buffer and flag the message for later buffering
if (_hubMessage.Position + _jsonMessageSize + 1 <= _hubMessage.Capacity)
{
// add the message and a comma to the buffer
_hubMessage.Write(
Encoding.UTF8.GetBytes(_jsonMessage.ToString(CultureInfo.InvariantCulture)),
0, _jsonMessageSize);
_hubMessage.Write(Encoding.UTF8.GetBytes(","), 0, 1);
_logger.Debug(
$"Added new IoT Central event message with size {_jsonMessageSize} to hub message (size is now {(_hubMessage.Position - 1)}).");
continue;
}
else
{
_needToBufferMessage = true;
}
}
}
else
{
_logger.Error("EventMessageData is null, there is a problem getting OPC UA Event data.");
}
}
else
{
// if we got no message, we either reached the interval or we are in shutdown and have processed all messages
if (_shutdownToken.IsCancellationRequested)
{
_logger.Information($"Cancellation requested.");
_monitoredIoTcEventDataQueue.CompleteAdding();
_monitoredIoTcEventDataQueue.Dispose();
return;
}
}
// the batching is completed or we reached the send interval or got a cancelation request
try
{
Microsoft.Azure.Devices.Client.Message encodedhubMessage = null;
// if we reached the send interval, but have nothing to send (only the opening square bracket is there), we continue
if (!gotItem && _hubMessage.Position == 1)
{
nextSendTime += TimeSpan.FromSeconds(_timeout);
_hubMessage.Position = 0;
_hubMessage.SetLength(0);
if (!_singleMessageSend)
{
_hubMessage.Write(Encoding.UTF8.GetBytes("["), 0, 1);
}
continue;
}
// if there is no batching and no send interval configured, we send the JSON message we just got, otherwise we send the buffer
if (_singleMessageSend)
{
// create the message without brackets
encodedhubMessage = new Message(Encoding.UTF8.GetBytes(_jsonMessage.ToString(CultureInfo.InvariantCulture)));
}
else
{
// remove the trailing comma and add a closing square bracket
_hubMessage.SetLength(_hubMessage.Length - 1);
_hubMessage.Write(Encoding.UTF8.GetBytes("]"), 0, 1);
encodedhubMessage = new Message(_hubMessage.ToArray());
}
if (_hubClient != null)
{
encodedhubMessage.ContentType = CONTENT_TYPE_OPCUAJSON;
encodedhubMessage.ContentEncoding = CONTENT_ENCODING_UTF8;
encodedhubMessage.Properties[HubCommunicationBase.MessageSchemaPropertyName] = HubCommunicationBase.MessageSchemaIotCentral;
nextSendTime += TimeSpan.FromSeconds(_timeout);
try
{
encodedhubMessage.Properties["endpointId"] = eventMessageData.EndpointId;
SentIoTcBytes += encodedhubMessage.GetBytes().Length;
await _hubClient.SendEventAsync(encodedhubMessage).ConfigureAwait(false);
SentIoTcEvents++;
_logger.Debug($"Sending {encodedhubMessage.BodyStream.Length} bytes to hub.");
_logger.Debug($"Message sent was: {_jsonMessage}");
}
catch
{
FailedIoTcMessages++;
}
// reset the messaage
_hubMessage.Position = 0;
_hubMessage.SetLength(0);
if (!_singleMessageSend)
{
_hubMessage.Write(Encoding.UTF8.GetBytes("["), 0, 1);
}
// if we had not yet buffered the last message because there was not enough space, buffer it now
if (_needToBufferMessage)
{
// add the message and a comma to the buffer
_hubMessage.Write(Encoding.UTF8.GetBytes(_jsonMessage.ToString(CultureInfo.InvariantCulture)), 0, _jsonMessageSize);
_hubMessage.Write(Encoding.UTF8.GetBytes(","), 0, 1);
}
}
else
{
_logger.Information("No hub client available. Dropping messages...");
}
}
catch (Exception e)
{
_logger.Error(e, "Exception while sending message to hub. Dropping message...");
}
}
catch (Exception e)
{
if (!(e is OperationCanceledException))
{
_logger.Error(e, "Error while processing monitored item messages.");
}
}
}
}
