SpanCreationOptions.Attributes changed to IEnumerable from IDictionary (#626)

* Remove non-working example from readme

* revert unintended changes

* SpanCreationOptions.Attributes changed to IEnumerable
Fix 588

* try tareks suggestion

* Fix builds

* revert unwanted changes

Co-authored-by: Sergey Kanzhelev <S.Kanzhelev@live.com>

src/OpenTelemetry.Api/Trace/SpanCreationOptions.cs

@@ -38,7 +38,7 @@ namespace OpenTelemetry.Trace
         /// <summary>
         /// Gets or sets attributes known prior to span creation.
         /// </summary>
-        public IDictionary<string, object> Attributes { get; set; }
+        public IEnumerable<KeyValuePair<string, object>> Attributes { get; set; }
 
         /// <summary>
         /// Gets or sets Links factory. Use it to deserialize list of <see cref="Link"/> lazily

src/OpenTelemetry/Trace/Internal/TagsCollection.cs

@@ -0,0 +1,61 @@
+// <copyright file="TagsCollection.cs" company="OpenTelemetry Authors">
+// Copyright 2018, 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;
+using System.Collections.Generic;
+
+namespace OpenTelemetry.Trace.Internal
+{
+    /// <summary>
+    /// Tags collection.
+    /// </summary>
+    internal struct TagsCollection : IEnumerable<KeyValuePair<string, object>>
+    {
+        private IEnumerable<KeyValuePair<string, string>> enumerable;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TagsCollection"/> struct.
+        /// </summary>
+        /// <param name="tags">the tags.</param>
+        public TagsCollection(IEnumerable<KeyValuePair<string, string>> tags)
+        {
+            this.enumerable = tags;
+        }
+
+        /// <inheritdoc/>
+        public IEnumerator GetEnumerator() => new TagsEnumerator(this.enumerable.GetEnumerator());
+
+        IEnumerator<KeyValuePair<string, object>> IEnumerable<KeyValuePair<string, object>>.GetEnumerator() => new TagsEnumerator(this.enumerable.GetEnumerator());
+
+        private struct TagsEnumerator : IDisposable, IEnumerator<KeyValuePair<string, object>>
+        {
+            private IEnumerator<KeyValuePair<string, string>> enumerator;
+
+            public TagsEnumerator(IEnumerator<KeyValuePair<string, string>> enumerator) => this.enumerator = enumerator;
+
+            KeyValuePair<string, object> IEnumerator<KeyValuePair<string, object>>.Current => new KeyValuePair<string, object>(this.enumerator.Current.Key, (object)this.enumerator.Current.Value);
+
+            object IEnumerator.Current => new KeyValuePair<string, object>(this.enumerator.Current.Key, (object)this.enumerator.Current.Value);
+
+            public void Dispose() => this.enumerator.Dispose();
+
+            public bool MoveNext() => this.enumerator.MoveNext();
+
+            public void Reset() => this.enumerator.Reset();
+        }
+    }
+}

src/OpenTelemetry/Trace/Sampler.cs

@@ -43,6 +43,6 @@ namespace OpenTelemetry.Trace
         /// <param name="attributes">Initial set of Attributes for the Span being constructed.</param>
         /// <param name="links">Links associated with the span.</param>
         /// <returns>Sampling decision on whether Span needs to be sampled or not.</returns>
-        public abstract SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IDictionary<string, object> attributes, IEnumerable<Link> links);
+        public abstract SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IEnumerable<KeyValuePair<string, object>> attributes, IEnumerable<Link> links);
     }
 }

src/OpenTelemetry/Trace/Samplers/AlwaysOffSampler.cs

@@ -27,7 +27,7 @@ namespace OpenTelemetry.Trace.Samplers
         public override string Description { get; } = nameof(AlwaysOffSampler);
 
         /// <inheritdoc />
-        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IDictionary<string, object> attributes, IEnumerable<Link> links)
+        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IEnumerable<KeyValuePair<string, object>> attributes, IEnumerable<Link> links)
         {
             return new SamplingResult(false);
         }

src/OpenTelemetry/Trace/Samplers/AlwaysOnSampler.cs

@@ -28,7 +28,7 @@ namespace OpenTelemetry.Trace.Samplers
         public override string Description { get; } = nameof(AlwaysOnSampler);
 
         /// <inheritdoc />
-        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IDictionary<string, object> attributes, IEnumerable<Link> parentLinks)
+        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IEnumerable<KeyValuePair<string, object>> attributes, IEnumerable<Link> parentLinks)
         {
             return new SamplingResult(true);
         }

src/OpenTelemetry/Trace/Samplers/AlwaysParentSampler.cs

@@ -28,7 +28,7 @@ namespace OpenTelemetry.Trace.Samplers
         public override string Description { get; } = nameof(AlwaysParentSampler);
 
         /// <inheritdoc />
-        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IDictionary<string, object> attributes, IEnumerable<Link> parentLinks)
+        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IEnumerable<KeyValuePair<string, object>> attributes, IEnumerable<Link> parentLinks)
         {
             if (parentContext.IsValid && parentContext.TraceFlags.HasFlag(ActivityTraceFlags.Recorded))
             {

src/OpenTelemetry/Trace/Samplers/ProbabilitySampler.cs

@@ -70,7 +70,7 @@ namespace OpenTelemetry.Trace.Samplers
         public override string Description { get; }
 
         /// <inheritdoc />
-        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IDictionary<string, object> attributes, IEnumerable<Link> links)
+        public override SamplingResult ShouldSample(in SpanContext parentContext, in ActivityTraceId traceId, in ActivitySpanId spanId, string name, SpanKind spanKind, IEnumerable<KeyValuePair<string, object>> attributes, IEnumerable<Link> links)
         {
             // If the parent is sampled keep the sampling decision.
             if (parentContext.IsValid &&

src/OpenTelemetry/Trace/SpanSdk.cs

@@ -620,7 +620,7 @@ namespace OpenTelemetry.Trace
             {
                 spanCreationOptions = new SpanCreationOptions
                 {
-                    Attributes = activity.Tags.ToDictionary(k => k.Key, v => (object)v.Value),
+                    Attributes = new TagsCollection(activity.Tags),
                 };
             }
 
@@ -674,7 +674,7 @@ namespace OpenTelemetry.Trace
             SpanContext parent,
             string name,
             SpanKind spanKind,
-            IDictionary<string, object> attributes,
+            IEnumerable<KeyValuePair<string, object>> attributes,
             IEnumerable<Link> parentLinks,
             ActivityTraceId traceId,
             ActivitySpanId spanId,