Custom Metric for Sequence Difference.cs

public class EventStreamBacklogTracing
{
    public static void LogSequenceDifference(EventData message, PartitionContext context)
    {
        var messageSequence = message.SystemProperties.SequenceNumber;
        var lastEnqueuedSequence = context.RuntimeInformation.LastSequenceNumber;
        var sequenceDifference = lastEnqueuedSequence - messageSequence;

        var client = new TelemetryClient();

        var metricData = client.GetMetric("PartitionSequenceDifference", "PartitionId", "ConsumerGroupName", "EventHubPath");

        metricData.TrackValue(sequenceDifference, context.PartitionId, context.ConsumerGroupName, context.EventHubPath);
    }
}