[OpenTelemetry] Use Regex source generator

Use `[GeneratedRegex]`, where supported, for statically-known regular expressions.

See open-telemetry#6849.

Co-Authored-By: Mihail Golubev <[email protected]>

Author: martincostello

src/OpenTelemetry/Internal/SelfDiagnosticsConfigParser.cs

@@ -8,7 +8,10 @@
 
 namespace OpenTelemetry.Internal;
 
-internal sealed class SelfDiagnosticsConfigParser
+/// <summary>
+/// Parses the self-diagnostics configuration file.
+/// </summary>
+internal sealed partial class SelfDiagnosticsConfigParser
 {
     public const string ConfigFileName = "OTEL_DIAGNOSTICS.json";
     private const int FileSizeLowerLimit = 1024;  // Lower limit for log file size in KB: 1MB
@@ -19,17 +22,20 @@ internal sealed class SelfDiagnosticsConfigParser
     /// </summary>
     private const int ConfigBufferSize = 4 * 1024;
 
-    private static readonly Regex LogDirectoryRegex = new(
-        @"""LogDirectory""\s*:\s*""(?<LogDirectory>.*?)""", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+    private const string LogDirectoryRegexPattern = @"""LogDirectory""\s*:\s*""(?<LogDirectory>.*?)""";
+    private const string FileSizeRegexPattern = @"""FileSize""\s*:\s*(?<FileSize>\d+)";
+    private const string LogLevelRegexPattern = @"""LogLevel""\s*:\s*""(?<LogLevel>.*?)""";
+    private const string FormatMessageRegexPattern = @"""FormatMessage""\s*:\s*(?:""(?<FormatMessage>.*?)""|(?<FormatMessage>true|false))";
 
-    private static readonly Regex FileSizeRegex = new(
-        @"""FileSize""\s*:\s*(?<FileSize>\d+)", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+#if !NET
+    private static readonly Regex LogDirectoryRegex = new(LogDirectoryRegexPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
-    private static readonly Regex LogLevelRegex = new(
-        @"""LogLevel""\s*:\s*""(?<LogLevel>.*?)""", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+    private static readonly Regex FileSizeRegex = new(FileSizeRegexPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
-    private static readonly Regex FormatMessageRegex = new(
-        @"""FormatMessage""\s*:\s*(?:""(?<FormatMessage>.*?)""|(?<FormatMessage>true|false))", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+    private static readonly Regex LogLevelRegex = new(LogLevelRegexPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
+    private static readonly Regex FormatMessageRegex = new(FormatMessageRegexPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
+#endif
 
     // This class is called in SelfDiagnosticsConfigRefresher.UpdateMemoryMappedFileFromConfiguration
     // in both main thread and the worker thread.
@@ -128,15 +134,15 @@ internal static bool TryParseLogDirectory(
         string configJson,
         out string logDirectory)
     {
-        var logDirectoryResult = LogDirectoryRegex.Match(configJson);
+        var logDirectoryResult = GetLogDirectoryRegex().Match(configJson);
         logDirectory = logDirectoryResult.Groups["LogDirectory"].Value;
         return logDirectoryResult.Success && !string.IsNullOrWhiteSpace(logDirectory);
     }
 
     internal static bool TryParseFileSize(string configJson, out int fileSizeInKB)
     {
         fileSizeInKB = 0;
-        var fileSizeResult = FileSizeRegex.Match(configJson);
+        var fileSizeResult = GetFileSizeRegex().Match(configJson);
         return fileSizeResult.Success && int.TryParse(fileSizeResult.Groups["FileSize"].Value, out fileSizeInKB);
     }
 
@@ -145,15 +151,15 @@ internal static bool TryParseLogLevel(
         [NotNullWhen(true)]
         out string? logLevel)
     {
-        var logLevelResult = LogLevelRegex.Match(configJson);
+        var logLevelResult = GetLogLevelRegex().Match(configJson);
         logLevel = logLevelResult.Groups["LogLevel"].Value;
         return logLevelResult.Success && !string.IsNullOrWhiteSpace(logLevel);
     }
 
     internal static bool TryParseFormatMessage(string configJson, out bool formatMessage)
     {
         formatMessage = false;
-        var formatMessageResult = FormatMessageRegex.Match(configJson);
+        var formatMessageResult = GetFormatMessageRegex().Match(configJson);
         if (formatMessageResult.Success)
         {
             var formatMessageValue = formatMessageResult.Groups["FormatMessage"].Value;
@@ -162,4 +168,26 @@ internal static bool TryParseFormatMessage(string configJson, out bool formatMes
 
         return true;
     }
+
+#if NET
+    [GeneratedRegex(LogDirectoryRegexPattern, RegexOptions.IgnoreCase)]
+    private static partial Regex GetLogDirectoryRegex();
+
+    [GeneratedRegex(FileSizeRegexPattern, RegexOptions.IgnoreCase)]
+    private static partial Regex GetFileSizeRegex();
+
+    [GeneratedRegex(LogLevelRegexPattern, RegexOptions.IgnoreCase)]
+    private static partial Regex GetLogLevelRegex();
+
+    [GeneratedRegex(FormatMessageRegexPattern, RegexOptions.IgnoreCase)]
+    private static partial Regex GetFormatMessageRegex();
+#else
+    private static Regex GetLogDirectoryRegex() => LogDirectoryRegex;
+
+    private static Regex GetFileSizeRegex() => FileSizeRegex;
+
+    private static Regex GetLogLevelRegex() => LogLevelRegex;
+
+    private static Regex GetFormatMessageRegex() => FormatMessageRegex;
+#endif
 }

src/OpenTelemetry/Metrics/Builder/MeterProviderBuilderSdk.cs

@@ -13,11 +13,12 @@ namespace OpenTelemetry.Metrics;
 /// <summary>
 /// Stores state used to build a <see cref="MeterProvider"/>.
 /// </summary>
-internal sealed class MeterProviderBuilderSdk : MeterProviderBuilder, IMeterProviderBuilder
+internal sealed partial class MeterProviderBuilderSdk : MeterProviderBuilder, IMeterProviderBuilder
 {
     public const int DefaultMetricLimit = 1000;
     public const int DefaultCardinalityLimit = 2000;
     private const string DefaultInstrumentationVersion = "1.0.0.0";
+    private const string InstrumentNameRegexPattern = @"^[a-z][a-z0-9-._/]{0,254}$";
 
     private readonly IServiceProvider serviceProvider;
     private MeterProviderSdk? meterProvider;
@@ -32,22 +33,21 @@ public MeterProviderBuilderSdk(IServiceProvider serviceProvider)
     // fields. See: https://github.com/dotnet/runtime/issues/11571.
     // Customers: This is not guaranteed to work forever. We may change this
     // mechanism in the future do this at your own risk.
-    public static Regex InstrumentNameRegex { get; set; } = new(
-        @"^[a-z][a-z0-9-._/]{0,254}$", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+    public static Regex InstrumentNameRegex { get; set; } = GetInstrumentNameRegex();
 
-    public List<InstrumentationRegistration> Instrumentation { get; } = new();
+    public List<InstrumentationRegistration> Instrumentation { get; } = [];
 
     public ResourceBuilder? ResourceBuilder { get; private set; }
 
     public ExemplarFilterType? ExemplarFilter { get; private set; }
 
     public MeterProvider? Provider => this.meterProvider;
 
-    public List<MetricReader> Readers { get; } = new();
+    public List<MetricReader> Readers { get; } = [];
 
-    public List<string> MeterSources { get; } = new();
+    public List<string> MeterSources { get; } = [];
 
-    public List<Func<Instrument, MetricStreamConfiguration?>> ViewConfigs { get; } = new();
+    public List<Func<Instrument, MetricStreamConfiguration?>> ViewConfigs { get; } = [];
 
     public int MetricLimit { get; private set; } = DefaultMetricLimit;
 
@@ -60,31 +60,17 @@ public MeterProviderBuilderSdk(IServiceProvider serviceProvider)
     /// <param name="instrumentName">The instrument name.</param>
     /// <returns>Boolean indicating if the instrument is valid.</returns>
     public static bool IsValidInstrumentName(string instrumentName)
-    {
-        if (string.IsNullOrWhiteSpace(instrumentName))
-        {
-            return false;
-        }
-
-        return InstrumentNameRegex.IsMatch(instrumentName);
-    }
+        => !string.IsNullOrWhiteSpace(instrumentName) && InstrumentNameRegex.IsMatch(instrumentName);
 
     /// <summary>
     /// Returns whether the given custom view name is valid according to the specification.
     /// </summary>
     /// <remarks>See specification: <see href="https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/api.md#instrument"/>.</remarks>
     /// <param name="customViewName">The view name.</param>
     /// <returns>Boolean indicating if the instrument is valid.</returns>
-    public static bool IsValidViewName(string customViewName)
-    {
-        // Only validate the view name in case it's not null. In case it's null, the view name will be the instrument name as per the spec.
-        if (customViewName == null)
-        {
-            return true;
-        }
-
-        return InstrumentNameRegex.IsMatch(customViewName);
-    }
+    public static bool IsValidViewName(string customViewName) =>
+        /* Only validate the view name in case it's not null. In case it's null, the view name will be the instrument name as per the spec. */
+        customViewName == null || InstrumentNameRegex.IsMatch(customViewName);
 
     public void RegisterProvider(MeterProviderSdk meterProvider)
     {
@@ -208,13 +194,18 @@ public MeterProviderBuilder ConfigureBuilder(Action<IServiceProvider, MeterProvi
     }
 
     public MeterProviderBuilder ConfigureServices(Action<IServiceCollection> configure)
-    {
-        throw new NotSupportedException("Services cannot be configured after ServiceProvider has been created.");
-    }
+        => throw new NotSupportedException("Services cannot be configured after ServiceProvider has been created.");
 
     MeterProviderBuilder IDeferredMeterProviderBuilder.Configure(Action<IServiceProvider, MeterProviderBuilder> configure)
         => this.ConfigureBuilder(configure);
 
+#if NET
+    [GeneratedRegex(InstrumentNameRegexPattern, RegexOptions.IgnoreCase)]
+    private static partial Regex GetInstrumentNameRegex();
+#else
+    private static Regex GetInstrumentNameRegex() => new(InstrumentNameRegexPattern, RegexOptions.IgnoreCase | RegexOptions.Compiled);
+#endif
+
     internal readonly struct InstrumentationRegistration
     {
         public readonly string Name;