feat: Add StackExchangeRedis Meter

src/OpenTelemetry.Instrumentation.StackExchangeRedis/Implementation/RedisMetrics.cs

@@ -0,0 +1,57 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Diagnostics.Metrics;
+using System.Reflection;
+using OpenTelemetry.Internal;
+
+namespace OpenTelemetry.Instrumentation.StackExchangeRedis.Implementation;
+
+internal class RedisMetrics : IDisposable
+{
+    internal const string MetricRequestDurationName = "redis.client.request.duration";
+    internal const string MetricWaitingResponseName = "redis.client.request.waiting_response";
+    internal const string MetricTimeInQueueName = "redis.client.request.time_in_queue";
+
+    internal static readonly Assembly Assembly = typeof(StackExchangeRedisInstrumentation).Assembly;
+    internal static readonly AssemblyName AssemblyName = Assembly.GetName();
+    internal static readonly string InstrumentationName = AssemblyName.Name;
+    internal static readonly string InstrumentationVersion = Assembly.GetPackageVersion();
+
+    private readonly Meter meter;
+
+    public RedisMetrics()
+    {
+        this.meter = new Meter(InstrumentationName, InstrumentationVersion);
+
+        this.QueueHistogram = this.meter.CreateHistogram<double>(
+            MetricTimeInQueueName,
+            unit: "s",
+            description: "Total time the redis request was waiting in queue before being sent to the server.");
+
+        this.WaitingResponseHistogram = this.meter.CreateHistogram<double>(
+            MetricWaitingResponseName,
+            unit: "s",
+            description: "Duration of redis requests since sent the request to receive the response.");
+
+        this.RequestHistogram = this.meter.CreateHistogram<double>(
+            MetricRequestDurationName,
+            unit: "s",
+            description: "Total client request duration, including processing, queue and server duration.");
+    }
+
+    public static RedisMetrics Instance { get; } = new RedisMetrics();
+
+    public Histogram<double> QueueHistogram { get; }
+
+    public Histogram<double> WaitingResponseHistogram { get; }
+
+    public Histogram<double> RequestHistogram { get; }
+
+    public bool Enabled => RequestHistogram.Enabled;
+
+    public void Dispose()
+    {
+        this.meter.Dispose();
+    }
+}

src/OpenTelemetry.Instrumentation.StackExchangeRedis/Implementation/RedisProfilerEntryToActivityConverter.cs → src/OpenTelemetry.Instrumentation.StackExchangeRedis/Implementation/RedisProfilerEntryInstrumenter.cs

@@ -14,7 +14,7 @@
 
 namespace OpenTelemetry.Instrumentation.StackExchangeRedis.Implementation;
 
-internal static class RedisProfilerEntryToActivityConverter
+internal static class RedisProfilerEntryInstrumenter
 {
     private static readonly Lazy<Func<object, (string?, string?)>> MessageDataGetter = new(() =>
     {
@@ -73,7 +73,11 @@ static bool GetCommandAndKey(
         });
     });
 
-    public static Activity? ProfilerCommandToActivity(Activity? parentActivity, IProfiledCommand command, StackExchangeRedisInstrumentationOptions options)
+    public static Activity? ProfilerCommandInstrument(
+        Activity? parentActivity,
+        IProfiledCommand command,
+        RedisMetrics metrics,
+        StackExchangeRedisInstrumentationOptions options)
     {
         var name = command.Command; // Example: SET;
         if (string.IsNullOrEmpty(name))
@@ -88,30 +92,36 @@ static bool GetCommandAndKey(
             StackExchangeRedisConnectionInstrumentation.CreationTags,
             startTime: command.CommandCreated);
 
-        if (activity == null)
+        if (activity is null && metrics.Enabled is false)
         {
             return null;
         }
 
-        activity.SetEndTime(command.CommandCreated + command.ElapsedTime);
+        activity?.SetEndTime(command.CommandCreated + command.ElapsedTime);
+        var meterTags = metrics.Enabled ?
+            (IList<KeyValuePair<string, object?>>)new TagList(StackExchangeRedisConnectionInstrumentation.CreationTags.ToArray()) :
+            default;
 
-        if (activity.IsAllDataRequested)
-        {
-            // see https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/database.md
+        // see https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/database.md
 
-            // Timing example:
-            // command.CommandCreated; //2019-01-10 22:18:28Z
+        // Timing example:
+        // command.CommandCreated; //2019-01-10 22:18:28Z
 
-            // command.CreationToEnqueued;      // 00:00:32.4571995
-            // command.EnqueuedToSending;       // 00:00:00.0352838
-            // command.SentToResponse;          // 00:00:00.0060586
-            // command.ResponseToCompletion;    // 00:00:00.0002601
+        // command.CreationToEnqueued;      // 00:00:32.4571995
+        // command.EnqueuedToSending;       // 00:00:00.0352838
+        // command.SentToResponse;          // 00:00:00.0060586
+        // command.ResponseToCompletion;    // 00:00:00.0002601
 
-            // Total:
-            // command.ElapsedTime;             // 00:00:32.4988020
+        // Total:
+        // command.ElapsedTime;             // 00:00:32.4988020
 
-            activity.SetTag(StackExchangeRedisConnectionInstrumentation.RedisFlagsKeyName, command.Flags.ToString());
+        var flags = command.Flags.ToString();
+        activity?.SetTag(SemanticConventions.AttributeDbRedisFlagsKeyName, flags);
+        meterTags?.Add(SemanticConventions.AttributeDbRedisFlagsKeyName, flags);
+        meterTags?.Add(SemanticConventions.AttributeDbStatement, command.Command ?? string.Empty);
 
+        if (activity is not null)
+        {
             if (options.SetVerboseDatabaseStatements)
             {
                 var (commandAndKey, script) = MessageDataGetter.Value.Invoke(command);
@@ -135,55 +145,93 @@ static bool GetCommandAndKey(
                 // Example: "db.statement": SET;
                 activity.SetTag(SemanticConventions.AttributeDbStatement, command.Command);
             }
+        }
 
-            if (command.EndPoint != null)
+        if (command.EndPoint != null)
+        {
+            if (command.EndPoint is IPEndPoint ipEndPoint)
             {
-                if (command.EndPoint is IPEndPoint ipEndPoint)
-                {
-                    activity.SetTag(SemanticConventions.AttributeNetPeerIp, ipEndPoint.Address.ToString());
-                    activity.SetTag(SemanticConventions.AttributeNetPeerPort, ipEndPoint.Port);
-                }
-                else if (command.EndPoint is DnsEndPoint dnsEndPoint)
-                {
-                    activity.SetTag(SemanticConventions.AttributeNetPeerName, dnsEndPoint.Host);
-                    activity.SetTag(SemanticConventions.AttributeNetPeerPort, dnsEndPoint.Port);
-                }
-                else
-                {
-                    activity.SetTag(SemanticConventions.AttributePeerService, command.EndPoint.ToString());
-                }
+                var ip = ipEndPoint.Address.ToString();
+                var port = ipEndPoint.Port;
+
+                activity?.SetTag(SemanticConventions.AttributeNetPeerIp, ip);
+                activity?.SetTag(SemanticConventions.AttributeNetPeerPort, port);
+
+                meterTags?.Add(SemanticConventions.AttributeNetPeerIp, ip);
+                meterTags?.Add(SemanticConventions.AttributeNetPeerPort, port);
+            }
+            else if (command.EndPoint is DnsEndPoint dnsEndPoint)
+            {
+                var host = dnsEndPoint.Host;
+                var port = dnsEndPoint.Port;
+
+                activity?.SetTag(SemanticConventions.AttributeNetPeerName, host);
+                activity?.SetTag(SemanticConventions.AttributeNetPeerPort, port);
+
+                meterTags?.Add(SemanticConventions.AttributeNetPeerName, host);
+                meterTags?.Add(SemanticConventions.AttributeNetPeerPort, port);
             }
+            else
+            {
+                var service = command.EndPoint.ToString();
+
+                activity?.SetTag(SemanticConventions.AttributePeerService, service);
+                meterTags?.Add(SemanticConventions.AttributePeerService, service);
+            }
+        }
 
-            activity.SetTag(StackExchangeRedisConnectionInstrumentation.RedisDatabaseIndexKeyName, command.Db);
+        var db = command.Db;
+        activity?.SetTag(SemanticConventions.AttributeDbRedisDatabaseIndex, db);
+        meterTags?.Add(SemanticConventions.AttributeDbRedisDatabaseIndex, db);
 
-            // TODO: deal with the re-transmission
-            // command.RetransmissionOf;
-            // command.RetransmissionReason;
+        // TODO: deal with the re-transmission
+        // command.RetransmissionOf;
+        // command.RetransmissionReason;
 
+        if (activity?.IsAllDataRequested ?? false)
+        {
             var enqueued = command.CommandCreated.Add(command.CreationToEnqueued);
             var send = enqueued.Add(command.EnqueuedToSending);
             var response = send.Add(command.SentToResponse);
+            var completion = send.Add(command.ResponseToCompletion);
 
             if (options.EnrichActivityWithTimingEvents)
             {
                 activity.AddEvent(new ActivityEvent("Enqueued", enqueued));
                 activity.AddEvent(new ActivityEvent("Sent", send));
                 activity.AddEvent(new ActivityEvent("ResponseReceived", response));
+                activity.AddEvent(new ActivityEvent("Completion", completion));
             }
 
             options.Enrich?.Invoke(activity, command);
         }
 
-        activity.Stop();
+        if (metrics.Enabled && meterTags is TagList meterTagList)
+        {
+            metrics.QueueHistogram.Record(command.EnqueuedToSending.TotalSeconds, meterTagList.ToArray());
+            metrics.WaitingResponseHistogram.Record(command.SentToResponse.TotalSeconds, meterTagList.ToArray());
+            metrics.RequestHistogram.Record(command.ElapsedTime.TotalSeconds, meterTagList.ToArray());
+        }
+
+        activity?.Stop();
 
         return activity;
     }
 
-    public static void DrainSession(Activity? parentActivity, IEnumerable<IProfiledCommand> sessionCommands, StackExchangeRedisInstrumentationOptions options)
+    private static void Add(this IList<KeyValuePair<string, object?>> tags, string ket, object? value)
+    {
+        tags?.Add(new KeyValuePair<string, object?>(ket, value));
+    }
+
+    public static void DrainSession(
+        Activity? parentActivity,
+        IEnumerable<IProfiledCommand> sessionCommands,
+        RedisMetrics redisMetrics,
+        StackExchangeRedisInstrumentationOptions options)
     {
         foreach (var command in sessionCommands)
         {
-            ProfilerCommandToActivity(parentActivity, command, options);
+            ProfilerCommandInstrument(parentActivity, command, redisMetrics, options);
         }
     }
 

src/OpenTelemetry.Instrumentation.StackExchangeRedis/README.md

@@ -8,7 +8,7 @@ This is an
 [Instrumentation Library](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/glossary.md#instrumentation-library),
 which instruments
 [StackExchange.Redis](https://www.nuget.org/packages/StackExchange.Redis/)
-and collects traces about outgoing calls to Redis.
+and collects traces and metrics about outgoing calls to Redis.
 
 > [!NOTE]
 > This component is based on the OpenTelemetry semantic conventions for
@@ -36,10 +36,12 @@ dotnet add package OpenTelemetry.Instrumentation.StackExchangeRedis
 ## Step 2: Enable StackExchange.Redis Instrumentation at application startup
 
 StackExchange.Redis instrumentation must be enabled at application startup.
-`AddRedisInstrumentation` method on `TracerProviderBuilder` must be called to
-enable Redis instrumentation, passing the `IConnectionMultiplexer` instance used
-to make Redis calls. Only those Redis calls made using the same instance of the
-`IConnectionMultiplexer` will be instrumented.
+`AddRedisInstrumentation` method on `TracerProviderBuilder` and/or
+`MeterProviderBuilder` must be called to enable Redis instrumentation, passing
+the `IConnectionMultiplexer` instance used to make Redis calls. Only those
+Redis calls made using the same instance of the `IConnectionMultiplexer` will
+be instrumented. Once tracing and metrics are enabled, any instrumented
+connection will export both signals.
 
 The following example demonstrates adding StackExchange.Redis instrumentation to
 a console application. This example also sets up the OpenTelemetry Console
@@ -61,6 +63,11 @@ public class Program
             .AddRedisInstrumentation(connection)
             .AddConsoleExporter()
             .Build();
+
+        using var tracerProvider = Sdk.CreateMeterProviderBuilder()
+            .AddRedisInstrumentation()
+            .AddConsoleExporter()
+            .Build();
     }
 }
 ```
@@ -88,6 +95,10 @@ using var connection = ConnectionMultiplexer.Connect("localhost:6379");
 using var tracerProvider = Sdk.CreateTracerProviderBuilder()
     .AddRedisInstrumentation(connection)
     .Build();
+
+using var tracerProvider = Sdk.CreateMeterProviderBuilder()
+    .AddRedisInstrumentation()
+    .Build();
 ```
 
 Whatever connection is specified will be collected by OpenTelemetry.
@@ -163,6 +174,9 @@ StackExchange.Redis by default does not give detailed database statements like
 what key or script was used during an operation. The `SetVerboseDatabaseStatements`
 option can be used to enable gathering this more detailed information.
 
+`SetVerboseDatabaseStatements` is not applied to metrics, only the command is
+defined in the statement attribute.
+
 The following example shows how to use `SetVerboseDatabaseStatements`.
 
 ```csharp
@@ -181,6 +195,8 @@ raw `IProfiledCommand` object. The `Enrich` action is called only when
 `activity.IsAllDataRequested` is `true`. It contains the activity itself (which can
 be enriched), and the source profiled command object.
 
+The `Enrich` action is not applied for metrics.
+
 The following code snippet shows how to add additional tags using `Enrich`.
 
 ```csharp

src/OpenTelemetry.Instrumentation.StackExchangeRedis/StackExchangeRedisConnectionInstrumentation.cs

@@ -17,8 +17,6 @@ namespace OpenTelemetry.Instrumentation.StackExchangeRedis;
 /// </summary>
 internal sealed class StackExchangeRedisConnectionInstrumentation : IDisposable
 {
-    internal const string RedisDatabaseIndexKeyName = "db.redis.database_index";
-    internal const string RedisFlagsKeyName = "db.redis.flags";
     internal static readonly Assembly Assembly = typeof(StackExchangeRedisConnectionInstrumentation).Assembly;
     internal static readonly string ActivitySourceName = Assembly.GetName().Name!;
     internal static readonly string ActivityName = ActivitySourceName + ".Execute";
@@ -50,6 +48,7 @@ public StackExchangeRedisConnectionInstrumentation(
     {
         Guard.ThrowIfNull(connection);
 
+        this.Connection = connection;
         this.options = options ?? new StackExchangeRedisInstrumentationOptions();
 
         this.drainThread = new Thread(this.DrainEntries)
@@ -62,6 +61,8 @@ public StackExchangeRedisConnectionInstrumentation(
         connection.RegisterProfiler(this.GetProfilerSessionsFactory());
     }
 
+    internal IConnectionMultiplexer Connection { get; }
+
     /// <summary>
     /// Returns session for the Redis calls recording.
     /// </summary>
@@ -108,7 +109,7 @@ public void Dispose()
 
     internal void Flush()
     {
-        RedisProfilerEntryToActivityConverter.DrainSession(null, this.defaultSession.FinishProfiling(), this.options);
+        RedisProfilerEntryInstrumenter.DrainSession(null, this.defaultSession.FinishProfiling(), RedisMetrics.Instance, this.options);
 
         foreach (var entry in this.Cache)
         {
@@ -120,7 +121,7 @@ internal void Flush()
             }
 
             ProfilingSession session = entry.Value.Session;
-            RedisProfilerEntryToActivityConverter.DrainSession(parent, session.FinishProfiling(), this.options);
+            RedisProfilerEntryInstrumenter.DrainSession(parent, session.FinishProfiling(), RedisMetrics.Instance, this.options);
             this.Cache.TryRemove((entry.Key.TraceId, entry.Key.SpanId), out _);
         }
     }