Binary search histograms

build/RELEASING.md

@@ -2,71 +2,24 @@
 
 Only for Maintainers.
 
- 1. Decide the tag name (version name) to be released.
-    eg: 1.0.0-rc2, 1.0.0 etc.
+1. Decide the tag name (version name) to be released.
+   eg: 1.0.0-rc2, 1.0.0 etc.
 
- 2. Run the following PowerShell from the root of the
-    repo to get combined changelog (to be used later).
+1. Run the following PowerShell from the root of the
+   repo to get combined changelog (to be used later).
 
-    ```powershell
-        $changelogs = Get-ChildItem -Path . -Recurse -Filter changelog.md
-        foreach ($changelog in $changelogs)
-        {
-         Add-Content -Path .\combinedchangelog.md -Value "**$($changelog.Directory.Name)**"
-         $lines = Get-Content -Path $changelog.FullName
-         $started = $false
-         $ended = $false
-         foreach ($line in $lines)
-             {
-                if($line -like "## Unreleased" -and $started -ne $true)
-                {
-                  $started = $true
-                }
-                elseif($line -like "## *" -and $started -eq $true)
-                {
-                  $ended = $true
-                  break
-                }
-                else
-                {
-                    if ($started -eq $true)
-                    {
-                        Add-Content -Path .\combinedchangelog.md $line
-                    }
-                }
-             }
-        }
-    ```
+    `./build/todo.ps1 1.0.0-rc2 | Set-Clipboard`
 
     This generates combined changelog to be used in Github release.
-    Once contents of combined changelog is saved somewhere,
-    delete the file.
-
- 3. Run the following PowerShell script from the root of the repo.
-    This updates all the changelog to have release date for the
-    current version being released.
-    Replace the version with actual version.
-    The actual version would be the tag name from step1.
-
-    ```powershell
-         $changelogs = Get-ChildItem -Path . -Recurse -Filter changelog.md
-        foreach ($changelog in $changelogs)
-        {
-         (Get-Content -Path $changelog.FullName) -replace "Unreleased", "Unreleased
-
-    ## 1.0.0-rc2
-
-    Released $(Get-Date -UFormat '%Y-%b-%d')" | Set-Content -Path $changelog.FullName
-        }
-    ```
+    Note: `git restore **/CHANGELOG.md` will undo changes to all CHANGELOG.md.
 
- 4. Normalize PublicApi files (Stable Release Only)
+4. Normalize PublicApi files (Stable Release Only)
     Run the PowerShell script `.\build\finalize-publicapi.ps1`.
     This will merge the contents of Unshipped.txt into the Shipped.txt.
 
- 5. Submit PR with the above changes, and get it merged.
+5. Submit PR with the above changes, and get it merged.
 
- 6. Tag Git with version to be released e.g.:
+6. Tag Git with version to be released e.g.:
 
     ```sh
     git tag -a 1.0.0-rc2 -m "1.0.0-rc2"
@@ -87,14 +40,14 @@ Only for Maintainers.
 
     If releasing both, push both tags above.
 
- 7. Open [Pack and publish to MyGet
+7. Open [Pack and publish to MyGet
     workflow](https://github.com/open-telemetry/opentelemetry-dotnet/actions/workflows/publish-packages-1.0.yml)
     and manually trigger a build. At the end of this, MyGet will have the
     packages. The package name will be the tag name used in step 5.
 
- 8. Validate using MyGet packages. Basic sanity checks :)
+8. Validate using MyGet packages. Basic sanity checks :)
 
- 9. From the above build, get the artifacts from the drop, which has all the
+9. From the above build, get the artifacts from the drop, which has all the
     NuGet packages.
 
 10. Copy all the NuGet files and symbols into a local folder. If only

src/OpenTelemetry/CHANGELOG.md

@@ -2,9 +2,12 @@
 
 ## Unreleased
 
+* Use binary search for histograms with a large amount of buckets.
+  ([#3251](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3251))
+
 * Exposed public setters for `LogRecord.State`, `LogRecord.StateValues`,
   and `LogRecord.FormattedMessage`.
- ([#3217](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3217))
+  ([#3217](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3217))
 
 ## 1.3.0-beta.1
 

src/OpenTelemetry/Metrics/Metric.cs

@@ -27,6 +27,8 @@ public sealed class Metric
     {
         internal static readonly double[] DefaultHistogramBounds = new double[] { 0, 5, 10, 25, 50, 75, 100, 250, 500, 1000 };
 
+        internal static readonly int DefaultHistogramCountForBinarySearch = 140;
+
         private readonly AggregatorStore aggStore;
 
         internal Metric(

src/OpenTelemetry/Metrics/MetricPoint.cs

@@ -30,6 +30,8 @@ public struct MetricPoint
 
         private readonly AggregationType aggType;
 
+        private readonly Func<double[], double, int> findHistogramBucketIndex;
+
         private HistogramBuckets histogramBuckets;
 
         // Represents temporality adjusted "value" for double/long metric types or "count" when histogram
@@ -61,6 +63,9 @@ internal MetricPoint(
             if (this.aggType == AggregationType.Histogram)
             {
                 this.histogramBuckets = new HistogramBuckets(histogramExplicitBounds);
+                this.findHistogramBucketIndex = histogramExplicitBounds.Length >= Metric.DefaultHistogramCountForBinarySearch
+                    ? FindHistogramBucketIndexBinary
+                    : FindHistogramBucketIndexLinear;
             }
             else if (this.aggType == AggregationType.HistogramSumCount)
             {
@@ -324,15 +329,9 @@ internal void Update(double number)
 
                 case AggregationType.Histogram:
                     {
-                        int i;
-                        for (i = 0; i < this.histogramBuckets.ExplicitBounds.Length; i++)
-                        {
-                            // Upper bound is inclusive
-                            if (number <= this.histogramBuckets.ExplicitBounds[i])
-                            {
-                                break;
-                            }
-                        }
+                        int i = double.IsNaN(number)
+                            ? this.histogramBuckets.ExplicitBounds.Length
+                            : this.findHistogramBucketIndex(this.histogramBuckets.ExplicitBounds, number);
 
                         var sw = default(SpinWait);
                         while (true)
@@ -545,5 +544,47 @@ private readonly void ThrowNotSupportedMetricTypeException(string methodName)
         {
             throw new NotSupportedException($"{methodName} is not supported for this metric type.");
         }
+
+#pragma warning disable SA1204 // Static elements should appear before instance elements
+        private static int FindHistogramBucketIndexLinear(double[] bounds, double number)
+#pragma warning restore SA1204 // Static elements should appear before instance elements
+        {
+            int i;
+
+            for (i = 0; i < bounds.Length; i++)
+            {
+                if (number <= bounds[i])
+                {
+                    break;
+                }
+            }
+
+            return i;
+        }
+
+        private static int FindHistogramBucketIndexBinary(double[] bounds, double number)
+        {
+            var left = 0;
+            var right = bounds.Length - 1;
+
+            while (left <= right)
+            {
+                var mid = (int)Math.Floor((double)(left + right) / 2);
+                if (number == bounds[mid])
+                {
+                    return mid;
+                }
+                else if (number > bounds[mid])
+                {
+                    left = mid + 1;
+                }
+                else
+                {
+                    right = mid - 1;
+                }
+            }
+
+            return right + 1;
+        }
     }
 }

test/Benchmarks/Metrics/HistogramBenchmarks.cs

@@ -59,15 +59,15 @@ namespace Benchmarks.Metrics
 {
     public class HistogramBenchmarks
     {
-        private const int MaxValue = 1000;
+        private const int MaxValue = 10000;
         private readonly Random random = new();
         private readonly string[] dimensionValues = new string[] { "DimVal1", "DimVal2", "DimVal3", "DimVal4", "DimVal5", "DimVal6", "DimVal7", "DimVal8", "DimVal9", "DimVal10" };
         private Histogram<long> histogram;
         private MeterProvider provider;
         private Meter meter;
         private double[] bounds;
 
-        [Params(10, 20, 50, 100)]
+        [Params(10, 20, 50, 100, 200, 500, 1000)]
         public int BoundCount { get; set; }
 
         [GlobalSetup]