Merge branch 'develop' into stable

1 files changed, 125 insertions, 0 deletions

diff --git a/src/SMAPI/Framework/PerformanceMonitoring/PerformanceCounter.cs b/src/SMAPI/Framework/PerformanceMonitoring/PerformanceCounter.cs
new file mode 100644
index 00000000..3cf668ee
--- /dev/null
+++ b/src/SMAPI/Framework/PerformanceMonitoring/PerformanceCounter.cs
@@ -0,0 +1,125 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Harmony;
+
+namespace StardewModdingAPI.Framework.PerformanceMonitoring
+{
+    /// <summary>Tracks metadata about a particular code event.</summary>
+    internal class PerformanceCounter
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The size of the ring buffer.</summary>
+        private readonly int MaxEntries = 16384;
+
+        /// <summary>The collection to which this performance counter belongs.</summary>
+        private readonly PerformanceCounterCollection ParentCollection;
+
+        /// <summary>The performance counter entries.</summary>
+        private readonly Stack<PerformanceCounterEntry> Entries;
+
+        /// <summary>The entry with the highest execution time.</summary>
+        private PerformanceCounterEntry? PeakPerformanceCounterEntry;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The name of the source.</summary>
+        public string Source { get; }
+
+        /// <summary>The alert threshold in milliseconds</summary>
+        public double AlertThresholdMilliseconds { get; set; }
+
+        /// <summary>If alerting is enabled or not</summary>
+        public bool EnableAlerts { get; set; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="parentCollection">The collection to which this performance counter belongs.</param>
+        /// <param name="source">The name of the source.</param>
+        public PerformanceCounter(PerformanceCounterCollection parentCollection, string source)
+        {
+            this.ParentCollection = parentCollection;
+            this.Source = source;
+            this.Entries = new Stack<PerformanceCounterEntry>(this.MaxEntries);
+        }
+
+        /// <summary>Add a performance counter entry to the list, update monitoring, and raise alerts if needed.</summary>
+        /// <param name="entry">The entry to add.</param>
+        public void Add(PerformanceCounterEntry entry)
+        {
+            // add entry
+            if (this.Entries.Count > this.MaxEntries)
+                this.Entries.Pop();
+            this.Entries.Add(entry);
+
+            // update metrics
+            if (this.PeakPerformanceCounterEntry == null || entry.ElapsedMilliseconds > this.PeakPerformanceCounterEntry.Value.ElapsedMilliseconds)
+                this.PeakPerformanceCounterEntry = entry;
+
+            // raise alert
+            if (this.EnableAlerts && entry.ElapsedMilliseconds > this.AlertThresholdMilliseconds)
+                this.ParentCollection.AddAlert(entry.ElapsedMilliseconds, this.AlertThresholdMilliseconds, new AlertContext(this.Source, entry.ElapsedMilliseconds));
+        }
+
+        /// <summary>Clear all performance counter entries and monitoring.</summary>
+        public void Reset()
+        {
+            this.Entries.Clear();
+            this.PeakPerformanceCounterEntry = null;
+        }
+
+        /// <summary>Get the peak entry.</summary>
+        public PerformanceCounterEntry? GetPeak()
+        {
+            return this.PeakPerformanceCounterEntry;
+        }
+
+        /// <summary>Get the entry with the highest execution time.</summary>
+        /// <param name="range">The time range to search.</param>
+        /// <param name="endTime">The end time for the <paramref name="range"/>, or null for the current time.</param>
+        public PerformanceCounterEntry? GetPeak(TimeSpan range, DateTime? endTime = null)
+        {
+            endTime ??= DateTime.UtcNow;
+            DateTime startTime = endTime.Value.Subtract(range);
+
+            return this.Entries
+                .Where(entry => entry.EventTime >= startTime && entry.EventTime <= endTime)
+                .OrderByDescending(x => x.ElapsedMilliseconds)
+                .FirstOrDefault();
+        }
+
+        /// <summary>Get the last entry added to the list.</summary>
+        public PerformanceCounterEntry? GetLastEntry()
+        {
+            if (this.Entries.Count == 0)
+                return null;
+
+            return this.Entries.Peek();
+        }
+
+        /// <summary>Get the average over a given time span.</summary>
+        /// <param name="range">The time range to search.</param>
+        /// <param name="endTime">The end time for the <paramref name="range"/>, or null for the current time.</param>
+        public double GetAverage(TimeSpan range, DateTime? endTime = null)
+        {
+            endTime ??= DateTime.UtcNow;
+            DateTime startTime = endTime.Value.Subtract(range);
+
+            double[] entries = this.Entries
+                .Where(entry => entry.EventTime >= startTime && entry.EventTime <= endTime)
+                .Select(p => p.ElapsedMilliseconds)
+                .ToArray();
+
+            return entries.Length > 0
+                ? entries.Average()
+                : 0;
+        }
+    }
+}