[sdk-metrics] Add support for .NET 9 Advice API

src/OpenTelemetry/Metrics/MetricStreamIdentity.cs

@@ -22,7 +22,7 @@ public MetricStreamIdentity(Instrument instrument, MetricStreamConfiguration? me
         this.ViewId = metricStreamConfiguration?.ViewId;
         this.MetricStreamName = $"{this.MeterName}.{this.MeterVersion}.{this.InstrumentName}";
         this.TagKeys = metricStreamConfiguration?.CopiedTagKeys;
-        this.HistogramBucketBounds = (metricStreamConfiguration as ExplicitBucketHistogramConfiguration)?.CopiedBoundaries;
+        this.HistogramBucketBounds = GetExplicitBucketHistogramBounds(instrument, metricStreamConfiguration);
         this.ExponentialHistogramMaxSize = (metricStreamConfiguration as Base2ExponentialBucketHistogramConfiguration)?.MaxSize ?? 0;
         this.ExponentialHistogramMaxScale = (metricStreamConfiguration as Base2ExponentialBucketHistogramConfiguration)?.MaxScale ?? 0;
         this.HistogramRecordMinMax = (metricStreamConfiguration as HistogramConfiguration)?.RecordMinMax ?? true;
@@ -150,6 +150,52 @@ public bool Equals(MetricStreamIdentity other)
 
     public override readonly int GetHashCode() => this.hashCode;
 
+    private static double[]? GetExplicitBucketHistogramBounds(Instrument instrument, MetricStreamConfiguration? metricStreamConfiguration)
+    {
+        if (metricStreamConfiguration is ExplicitBucketHistogramConfiguration explicitBucketHistogramConfiguration
+            && explicitBucketHistogramConfiguration.CopiedBoundaries != null)
+        {
+            return explicitBucketHistogramConfiguration.CopiedBoundaries;
+        }
+
+        return instrument switch
+        {
+            Histogram<long> longHistogram => GetExplicitBucketHistogramBoundsFromAdvice(longHistogram),
+            Histogram<int> intHistogram => GetExplicitBucketHistogramBoundsFromAdvice(intHistogram),
+            Histogram<short> shortHistogram => GetExplicitBucketHistogramBoundsFromAdvice(shortHistogram),
+            Histogram<byte> byteHistogram => GetExplicitBucketHistogramBoundsFromAdvice(byteHistogram),
+            Histogram<float> floatHistogram => GetExplicitBucketHistogramBoundsFromAdvice(floatHistogram),
+            Histogram<double> doubleHistogram => GetExplicitBucketHistogramBoundsFromAdvice(doubleHistogram),
+            _ => null,
+        };
+    }
+
+    private static double[]? GetExplicitBucketHistogramBoundsFromAdvice<T>(Histogram<T> histogram)
+        where T : struct
+    {
+        var adviceExplicitBucketBoundaries = histogram.Advice?.HistogramBucketBoundaries;
+        if (adviceExplicitBucketBoundaries == null)
+        {
+            return null;
+        }
+
+        if (typeof(T) == typeof(double))
+        {
+            return ((IReadOnlyList<double>)adviceExplicitBucketBoundaries).ToArray();
+        }
+        else
+        {
+            double[] explicitBucketBoundaries = new double[adviceExplicitBucketBoundaries.Count];
+
+            for (int i = 0; i < adviceExplicitBucketBoundaries.Count; i++)
+            {
+                explicitBucketBoundaries[i] = Convert.ToDouble(adviceExplicitBucketBoundaries[i]);
+            }
+
+            return explicitBucketBoundaries;
+        }
+    }
+
     private static bool HistogramBoundsEqual(double[]? bounds1, double[]? bounds2)
     {
         if (ReferenceEquals(bounds1, bounds2))

test/OpenTelemetry.Tests/Metrics/MetricViewTests.cs

@@ -570,6 +570,130 @@ public void ViewToProduceCustomHistogramBound()
         Assert.Equal(boundaries.Length + 1, actualCount);
     }
 
+    [Fact]
+    public void AdviceToProduceCustomHistogramBound()
+    {
+        using var meter = new Meter(Utils.GetCurrentMethodName());
+        var exportedItems = new List<Metric>();
+        IReadOnlyList<long> boundaries = new List<long>() { 10, 20 };
+
+        using var container = this.BuildMeterProvider(out var meterProvider, builder => builder
+            .AddMeter(meter.Name)
+            .AddInMemoryExporter(exportedItems));
+
+        var histogram = meter.CreateHistogram<long>(
+            "MyHistogram",
+            unit: null,
+            description: null,
+            tags: null,
+            new()
+            {
+                HistogramBucketBoundaries = boundaries,
+            });
+        histogram.Record(-10);
+        histogram.Record(0);
+        histogram.Record(1);
+        histogram.Record(9);
+        histogram.Record(10);
+        histogram.Record(11);
+        histogram.Record(19);
+        meterProvider.ForceFlush(MaxTimeToAllowForFlush);
+        Assert.Single(exportedItems);
+        var metricCustom = exportedItems[0];
+
+        Assert.Equal("MyHistogram", metricCustom.Name);
+
+        List<MetricPoint> metricPointsCustom = new List<MetricPoint>();
+        foreach (ref readonly var mp in metricCustom.GetMetricPoints())
+        {
+            metricPointsCustom.Add(mp);
+        }
+
+        Assert.Single(metricPointsCustom);
+        var histogramPoint = metricPointsCustom[0];
+
+        var count = histogramPoint.GetHistogramCount();
+        var sum = histogramPoint.GetHistogramSum();
+
+        Assert.Equal(40, sum);
+        Assert.Equal(7, count);
+
+        var index = 0;
+        var actualCount = 0;
+        var expectedBucketCounts = new long[] { 5, 2, 0 };
+        foreach (var histogramMeasurement in histogramPoint.GetHistogramBuckets())
+        {
+            Assert.Equal(expectedBucketCounts[index], histogramMeasurement.BucketCount);
+            index++;
+            actualCount++;
+        }
+
+        Assert.Equal(boundaries.Count + 1, actualCount);
+    }
+
+    [Fact]
+    public void ViewTakesPrecedenceOverAdviceToProduceCustomHistogramBound()
+    {
+        using var meter = new Meter(Utils.GetCurrentMethodName());
+        var exportedItems = new List<Metric>();
+        IReadOnlyList<long> adviceBoundaries = new List<long>() { 5, 10, 20 };
+        var viewBoundaries = new double[] { 10, 20 };
+
+        using var container = this.BuildMeterProvider(out var meterProvider, builder => builder
+            .AddMeter(meter.Name)
+            .AddView("MyHistogram", new ExplicitBucketHistogramConfiguration() { Boundaries = viewBoundaries })
+            .AddInMemoryExporter(exportedItems));
+
+        var histogram = meter.CreateHistogram<long>(
+            "MyHistogram",
+            unit: null,
+            description: null,
+            tags: null,
+            new()
+            {
+                HistogramBucketBoundaries = adviceBoundaries,
+            });
+        histogram.Record(-10);
+        histogram.Record(0);
+        histogram.Record(1);
+        histogram.Record(9);
+        histogram.Record(10);
+        histogram.Record(11);
+        histogram.Record(19);
+        meterProvider.ForceFlush(MaxTimeToAllowForFlush);
+        Assert.Single(exportedItems);
+        var metricCustom = exportedItems[0];
+
+        Assert.Equal("MyHistogram", metricCustom.Name);
+
+        List<MetricPoint> metricPointsCustom = new List<MetricPoint>();
+        foreach (ref readonly var mp in metricCustom.GetMetricPoints())
+        {
+            metricPointsCustom.Add(mp);
+        }
+
+        Assert.Single(metricPointsCustom);
+        var histogramPoint = metricPointsCustom[0];
+
+        var count = histogramPoint.GetHistogramCount();
+        var sum = histogramPoint.GetHistogramSum();
+
+        Assert.Equal(40, sum);
+        Assert.Equal(7, count);
+
+        var index = 0;
+        var actualCount = 0;
+        var expectedBucketCounts = new long[] { 5, 2, 0 };
+        foreach (var histogramMeasurement in histogramPoint.GetHistogramBuckets())
+        {
+            Assert.Equal(expectedBucketCounts[index], histogramMeasurement.BucketCount);
+            index++;
+            actualCount++;
+        }
+
+        Assert.Equal(viewBoundaries.Length + 1, actualCount);
+    }
+
     [Fact]
     public void ViewToProduceExponentialHistogram()
     {