Extend Monitoring.Cpu with field initializers and a load limit.

Refers to #36

ATxCommon/Monitoring/Cpu.cs

 using System;
 using System.Diagnostics;
 using System.Linq;
+using System.Threading;
 using System.Timers;
 using NLog;
+using Timer = System.Timers.Timer;
 
 namespace ATxCommon.Monitoring
 {
@@ -13,26 +15,78 @@ namespace ATxCommon.Monitoring
         private readonly Timer _monitoringTimer;
         private readonly PerformanceCounter _cpuCounter;
         private readonly float[] _loadReadings = {0F, 0F, 0F, 0F};
+
         private float _load;
+        private int _interval;
+        private int _limit;
+        private int _behaving;
+        private int _probation;
+        private bool _enabled;
+
 
         public float Load() => _load;
 
+        public int Interval {
+            get => _interval;
+            set {
+                _interval = value;
+                _monitoringTimer.Interval = value;
+                Log.Debug("CPU monitoring interval: {0}", _interval);
+            }
+        }
+
+        public int Limit {
+            get => _limit;
+            set {
+                _limit = value;
+                Log.Debug("CPU monitoring limit: {0}", _limit);
+            }
+        }
+
+        public int Probation {
+            get => _probation;
+            set {
+                _probation = value;
+                Log.Debug("CPU monitoring probation cycles when violating limit: {0}", _probation);
+            }
+        }
+        
+        public bool Enabled {
+            get => _enabled;
+            set => EnableTimer(value);
+        }
+
+
         public Cpu() {
+            _interval = 250;
+            _limit = 25;
+            _probation = 40;
             Log.Debug("Initializing CPU monitoring...");
+            
             try {
                 _cpuCounter = new PerformanceCounter("Processor", "% Processor Time", "_Total");
-                _monitoringTimer = new Timer(250);
+                Log.Debug("CPU monitoring initializing PerformanceCounter (takes 1s)...");
+                _cpuCounter.NextValue();
+                Thread.Sleep(1000);
+                Log.Debug("CPU monitoring current load: {0}", _cpuCounter.NextValue());
+                // _monitoringTimer = new Timer(_interval);
+                _monitoringTimer = new Timer(_interval);
                 _monitoringTimer.Elapsed += UpdateCpuLoad;
-                _monitoringTimer.Enabled = true;
             }
-            catch (Exception ex) {
-                Log.Error("Initializing CPU monitoring completed ({1}): {0}", ex.Message, ex.GetType());
+            catch (Exception) {
+                Log.Error("Initializing CPU monitoring failed!");
                 throw;
             }
 
             Log.Debug("Initializing CPU monitoring completed.");
         }
 
+        private void EnableTimer(bool enabled) {
+            Log.Debug("{0} CPU monitoring.", enabled ? "Enabling" : "Disabling");
+            _monitoringTimer.Enabled = enabled;
+            _enabled = enabled;
+        }
+
         private void UpdateCpuLoad(object sender, ElapsedEventArgs e) {
             _monitoringTimer.Enabled = false;
             try {
@@ -42,6 +96,22 @@ namespace ATxCommon.Monitoring
                 _loadReadings[3] = _cpuCounter.NextValue();
                 _load = _loadReadings.Average();
                 Log.Trace("load values: {0}, average: {1}", string.Join(", ", _loadReadings), _load);
+                if (_loadReadings[3] > _limit) {
+                    Log.Debug("CPU load ({0}) violating limit ({1})!", _loadReadings[3], _limit);
+                    _behaving = 0;
+                    // TODO: fire callback for violating load limit
+                } else {
+                    _behaving++;
+                    if (_behaving == _probation) {
+                        Log.Debug("CPU load below limit for {0} cycles, yay!", _probation);
+                        // TODO: fire callback for load behaving well
+                    } else if (_behaving > _probation) {
+                        Log.Debug("CPU load behaving well since {0} cycles.", _behaving);
+                    } else if (_behaving < 0) {
+                        Log.Warn("Integer wrap around happened, resetting probation counter!");
+                        _behaving = 0;
+                    }
+                }
             }
             catch (Exception ex) {
                 Log.Error("UpdateCpuLoad failed: {0}", ex.Message);