Add ActivityExporter for Zipkin

src/OpenTelemetry.Exporter.Zipkin/Implementation/ZipkinActivityConversionExtensions.cs

@@ -0,0 +1,229 @@
+// <copyright file="ZipkinActivityConversionExtensions.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics;
+using OpenTelemetry.Internal;
+using OpenTelemetry.Resources;
+using OpenTelemetry.Trace;
+
+namespace OpenTelemetry.Exporter.Zipkin.Implementation
+{
+    internal static class ZipkinActivityConversionExtensions
+    {
+        private const long TicksPerMicrosecond = TimeSpan.TicksPerMillisecond / 1000;
+
+        private static readonly Dictionary<string, int> RemoteEndpointServiceNameKeyResolutionDictionary = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)
+        {
+            [SpanAttributeConstants.PeerServiceKey] = 0, // RemoteEndpoint.ServiceName primary.
+            ["net.peer.name"] = 1, // RemoteEndpoint.ServiceName first alternative.
+            ["peer.hostname"] = 2, // RemoteEndpoint.ServiceName second alternative.
+            ["peer.address"] = 2, // RemoteEndpoint.ServiceName second alternative.
+            ["http.host"] = 3, // RemoteEndpoint.ServiceName for Http.
+            ["db.instance"] = 4, // RemoteEndpoint.ServiceName for Redis.
+        };
+
+        private static readonly string InvalidSpanId = default(ActivitySpanId).ToHexString();
+
+        private static readonly ConcurrentDictionary<string, ZipkinEndpoint> LocalEndpointCache = new ConcurrentDictionary<string, ZipkinEndpoint>();
+        private static readonly ConcurrentDictionary<string, ZipkinEndpoint> RemoteEndpointCache = new ConcurrentDictionary<string, ZipkinEndpoint>();
+
+        private static readonly DictionaryEnumerator<string, string, AttributeEnumerationState>.ForEachDelegate ProcessTagsRef = ProcessTags;
+        private static readonly ListEnumerator<ActivityEvent, PooledList<ZipkinAnnotation>>.ForEachDelegate ProcessActivityEventsRef = ProcessActivityEvents;
+
+        internal static ZipkinSpan ToZipkinSpan(this Activity activity, ZipkinEndpoint defaultLocalEndpoint, bool useShortTraceIds = false)
+        {
+            var context = activity.Context;
+            var startTimestamp = activity.StartTimeUtc.ToEpochMicroseconds();
+
+            string parentId = EncodeSpanId(activity.ParentSpanId);
+            if (string.Equals(parentId, InvalidSpanId, StringComparison.Ordinal))
+            {
+                parentId = null;
+            }
+
+            var attributeEnumerationState = new AttributeEnumerationState
+            {
+                Tags = PooledList<KeyValuePair<string, string>>.Create(),
+            };
+
+            DictionaryEnumerator<string, string, AttributeEnumerationState>.AllocationFreeForEach(activity.Tags, ref attributeEnumerationState, ProcessTagsRef);
+
+            var activitySource = activity.Source;
+            if (!string.IsNullOrEmpty(activitySource.Name))
+            {
+                PooledList<KeyValuePair<string, string>>.Add(ref attributeEnumerationState.Tags, new KeyValuePair<string, string>("library.name", activitySource.Name));
+                if (!string.IsNullOrEmpty(activitySource.Version))
+                {
+                    PooledList<KeyValuePair<string, string>>.Add(ref attributeEnumerationState.Tags, new KeyValuePair<string, string>("library.version", activitySource.Version));
+                }
+            }
+
+            var localEndpoint = defaultLocalEndpoint;
+
+            var serviceName = attributeEnumerationState.ServiceName;
+
+            // override default service name
+            if (!string.IsNullOrWhiteSpace(serviceName))
+            {
+                if (!string.IsNullOrWhiteSpace(attributeEnumerationState.ServiceNamespace))
+                {
+                    serviceName = attributeEnumerationState.ServiceNamespace + "." + serviceName;
+                }
+
+                if (!LocalEndpointCache.TryGetValue(serviceName, out localEndpoint))
+                {
+                    localEndpoint = defaultLocalEndpoint.Clone(serviceName);
+                    LocalEndpointCache.TryAdd(serviceName, localEndpoint);
+                }
+            }
+
+            ZipkinEndpoint remoteEndpoint = null;
+            if ((activity.Kind == ActivityKind.Client || activity.Kind == ActivityKind.Producer) && attributeEnumerationState.RemoteEndpointServiceName != null)
+            {
+                remoteEndpoint = RemoteEndpointCache.GetOrAdd(attributeEnumerationState.RemoteEndpointServiceName, ZipkinEndpoint.Create);
+            }
+
+            var annotations = PooledList<ZipkinAnnotation>.Create();
+            ListEnumerator<ActivityEvent, PooledList<ZipkinAnnotation>>.AllocationFreeForEach(activity.Events, ref annotations, ProcessActivityEventsRef);
+
+            return new ZipkinSpan(
+                EncodeTraceId(context.TraceId, useShortTraceIds),
+                parentId,
+                EncodeSpanId(context.SpanId),
+                ToActivityKind(activity),
+                activity.OperationName,
+                activity.StartTimeUtc.ToEpochMicroseconds(),
+                duration: (long)activity.Duration.ToEpochMicroseconds(),
+                localEndpoint,
+                remoteEndpoint,
+                annotations,
+                attributeEnumerationState.Tags,
+                null,
+                null);
+        }
+
+        internal static string EncodeSpanId(ActivitySpanId spanId)
+        {
+            return spanId.ToHexString();
+        }
+
+        internal static long ToEpochMicroseconds(this DateTimeOffset dateTimeOffset)
+        {
+            return dateTimeOffset.Ticks / TicksPerMicrosecond;
+        }
+
+        internal static long ToEpochMicroseconds(this TimeSpan timeSpan)
+        {
+            return timeSpan.Ticks / TicksPerMicrosecond;
+        }
+
+        internal static long ToEpochMicroseconds(this DateTime utcDateTime)
+        {
+            const long UnixEpochTicks = 621355968000000000L; // = DateTimeOffset.FromUnixTimeMilliseconds(0).Ticks
+            const long UnixEpochMicroseconds = UnixEpochTicks / TicksPerMicrosecond;
+
+            // Truncate sub-microsecond precision before offsetting by the Unix Epoch to avoid
+            // the last digit being off by one for dates that result in negative Unix times
+            long microseconds = utcDateTime.Ticks / TicksPerMicrosecond;
+            return microseconds - UnixEpochMicroseconds;
+        }
+
+        private static string EncodeTraceId(ActivityTraceId traceId, bool useShortTraceIds)
+        {
+            var id = traceId.ToHexString();
+
+            if (id.Length > 16 && useShortTraceIds)
+            {
+                id = id.Substring(id.Length - 16, 16);
+            }
+
+            return id;
+        }
+
+        private static string ToActivityKind(Activity activity)
+        {
+            switch (activity.Kind)
+            {
+                case ActivityKind.Server:
+                    return "SERVER";
+                case ActivityKind.Producer:
+                    return "PRODUCER";
+                case ActivityKind.Consumer:
+                    return "CONSUMER";
+                case ActivityKind.Client:
+                    return "CLIENT";
+            }
+
+            return null;
+        }
+
+        private static bool ProcessActivityEvents(ref PooledList<ZipkinAnnotation> annotations, ActivityEvent @event)
+        {
+            PooledList<ZipkinAnnotation>.Add(ref annotations, new ZipkinAnnotation(@event.Timestamp.ToEpochMicroseconds(), @event.Name));
+            return true;
+        }
+
+        private static bool ProcessTags(ref AttributeEnumerationState state, KeyValuePair<string, string> attribute)
+        {
+            string key = attribute.Key;
+            string strVal = attribute.Value;
+
+            if (strVal != null)
+            {
+                if (RemoteEndpointServiceNameKeyResolutionDictionary.TryGetValue(key, out int priority)
+                    && (state.RemoteEndpointServiceName == null || priority < state.RemoteEndpointServiceNamePriority))
+                {
+                    state.RemoteEndpointServiceName = strVal;
+                    state.RemoteEndpointServiceNamePriority = priority;
+                }
+                else if (key == Resource.ServiceNameKey)
+                {
+                    state.ServiceName = strVal;
+                }
+                else if (key == Resource.ServiceNamespaceKey)
+                {
+                    state.ServiceNamespace = strVal;
+                }
+                else
+                {
+                    PooledList<KeyValuePair<string, string>>.Add(ref state.Tags, new KeyValuePair<string, string>(key, strVal));
+                }
+            }
+            else
+            {
+                PooledList<KeyValuePair<string, string>>.Add(ref state.Tags, new KeyValuePair<string, string>(key, strVal));
+            }
+
+            return true;
+        }
+
+        private struct AttributeEnumerationState
+        {
+            public PooledList<KeyValuePair<string, string>> Tags;
+
+            public string RemoteEndpointServiceName;
+
+            public int RemoteEndpointServiceNamePriority;
+
+            public string ServiceName;
+
+            public string ServiceNamespace;
+        }
+    }
+}

src/OpenTelemetry.Exporter.Zipkin/Implementation/ZipkinSpan.cs

@@ -112,7 +112,10 @@ public void Write(Utf8JsonWriter writer)
 
             writer.WriteString("id", this.Id);
 
-            writer.WriteString("kind", this.Kind);
+            if (this.Kind != null)
+            {
+                writer.WriteString("kind", this.Kind);
+            }
 
             if (this.Timestamp.HasValue)
             {

src/OpenTelemetry.Exporter.Zipkin/TracerBuilderExtensions.cs

@@ -83,5 +83,33 @@ public static TracerBuilder UseZipkin(this TracerBuilder builder, Action<ZipkinT
                 processorConfigure.Invoke(b);
             });
         }
+
+        /// <summary>
+        /// Registers a Zipkin exporter that will receive <see cref="System.Diagnostics.Activity"/> instances.
+        /// </summary>
+        /// <param name="builder"><see cref="OpenTelemetryBuilder"/> builder to use.</param>
+        /// <param name="configure">Exporter configuration options.</param>
+        /// <returns>The instance of <see cref="OpenTelemetryBuilder"/> to chain the calls.</returns>
+        public static OpenTelemetryBuilder UseZipkinActivityExporter(this OpenTelemetryBuilder builder, Action<ZipkinTraceExporterOptions> configure)
+        {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (configure == null)
+            {
+                throw new ArgumentNullException(nameof(configure));
+            }
+
+            return builder.AddProcessorPipeline(pipeline =>
+            {
+                var options = new ZipkinTraceExporterOptions();
+                configure(options);
+
+                var activityExporter = new ZipkinActivityExporter(options);
+                pipeline.SetExporter(activityExporter);
+            });
+        }
     }
 }