OhmGraphite/OhmGraphite/MetricTimer.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Timers;
using NLog;

namespace OhmGraphite
{
    public class MetricTimer : IManage
    {
        private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
        private readonly SensorCollector _collector;

        private readonly Timer _timer;
        private readonly IWriteMetrics _writer;

        public MetricTimer(TimeSpan interval, SensorCollector collector, IWriteMetrics writer)
        {
            _timer = new Timer(interval.TotalMilliseconds) {AutoReset = true};
            _timer.Elapsed += ReportMetrics;
            _collector = collector;
            _writer = writer;
        }

        public void Start()
        {
            Logger.LogAction("starting metric timer", () =>
            {
                _collector.Open();
                _timer.Start();
            });
        }

        public void Stop()
        {
            Logger.LogAction("stopping metric timer", () =>
            {
                _collector.Close();
                _timer.Stop();
            });
        }

        private async void ReportMetrics(object sender, ElapsedEventArgs e)
        {
            Logger.Debug("Starting to report metrics");
            try
            {
                // Every 5 seconds (or superceding interval) we connect to graphite
                // and poll the hardware. It may be inefficient to open a new connection
                // every 5 seconds, and there are ways to optimize this, but opening a
                // new connection is the easiest way to ensure that previous failures
                // don't affect future results
                var stopwatch = Stopwatch.StartNew();
                var sensors = _collector.ReadAllSensors().ToList();
                await _writer.ReportMetrics(e.SignalTime, sensors);
                Logger.Info($"Sent {sensors.Count} metrics in {stopwatch.Elapsed.TotalMilliseconds}ms");
            }
            catch (Exception ex)
            {
                Logger.Error(ex, "Unable to send metrics");
            }
        }
    }
}