Add TracerBuilder extension to configure Jaeger (#347)

* add TracerBuilder extension to configure Jaeger

* update jaeger example and README

README.md

@@ -357,22 +357,19 @@ the Compact Thrift API port. You can configure the Jaeger exporter by following
 3. See the [sample][jaeger-sample] for an example of how to use the exporter.
 
 ```csharp
-var jaegerOptions = new JaegerExporterOptions()
-{
-    ServiceName = "jaeger-test",
-    AgentHost = <jaeger server>
-};
-
-using (var tracerFactory = TracerFactory.Create(builder => builder
-    .AddProcessorPipeline(c => c.SetExporter(new JaegerTraceExporter(jaegerOptions)))))
+using (var tracerFactory = TracerFactory.Create(
+    builder => builder.UseJaeger(o =>
+    {
+        o.ServiceName = "jaeger-test";
+        o.AgentHost = "<jaeger server>";
+    })))
 {
     var tracer = tracerFactory.GetTracer("jaeger-test");
-    var span = tracer
-        .SpanBuilder("incoming request")
-        .StartSpan();
-
-    await Task.Delay(1000);
-    span.End();
+    using (tracer.StartActiveSpan("incoming request", out var span))
+    {
+        span.SetAttribute("custom-attribute", 55);
+        await Task.Delay(1000);
+    }
 }
 ```
 

samples/Exporters/TestJaeger.cs

@@ -26,17 +26,14 @@ namespace Samples
     {
         internal static object Run(string host, int port)
         {
-            // Configure exporter to export traces to Jaeger
-            var jaegerOptions = new JaegerExporterOptions()
-            {
-                ServiceName = "jaeger-test",
-                AgentHost = host,
-                AgentPort = port,
-            };
-
-            // Create a tracer. 
-            using (var tracerFactory = TracerFactory.Create(builder => builder
-                .AddProcessorPipeline(c => c.SetExporter(new JaegerTraceExporter(jaegerOptions)))))
+            // Create a tracer.
+            using (var tracerFactory = TracerFactory.Create(
+                builder => builder.UseJaeger(o =>
+                {
+                    o.ServiceName = "jaeger-test";
+                    o.AgentHost = host;
+                    o.AgentPort = port;
+                })))
             {
                 var tracer = tracerFactory.GetTracer("jaeger-test");
 

src/OpenTelemetry.Exporter.Jaeger/TracerBuilderExtensions.cs

@@ -0,0 +1,86 @@
+// <copyright file="TracerBuilderExtensions.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 OpenTelemetry.Exporter.Jaeger;
+using OpenTelemetry.Trace.Export;
+
+namespace OpenTelemetry.Trace.Configuration
+{
+    /// <summary>
+    /// Extension methods to simplify registering a Jaeger exporter.
+    /// </summary>
+    public static class TracerBuilderExtensions
+    {
+        /// <summary>
+        /// Registers a Jaeger exporter.
+        /// </summary>
+        /// <param name="builder">Trace builder to use.</param>
+        /// <param name="configure">Exporter configuration options.</param>
+        /// <returns>The instance of <see cref="TracerBuilder"/> to chain the calls.</returns>
+        public static TracerBuilder UseJaeger(this TracerBuilder builder, Action<JaegerExporterOptions> configure)
+        {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (configure == null)
+            {
+                throw new ArgumentNullException(nameof(configure));
+            }
+
+            var options = new JaegerExporterOptions();
+            configure(options);
+            return builder.AddProcessorPipeline(b => b
+                .SetExporter(new JaegerTraceExporter(options))
+                .SetExportingProcessor(e => new BatchingSpanProcessor(e)));
+        }
+
+        /// <summary>
+        /// Registers Jaeger exporter.
+        /// </summary>
+        /// <param name="builder">Trace builder to use.</param>
+        /// <param name="configure">Exporter configuration options.</param>
+        /// <param name="processorConfigure">Span processor configuration.</param>
+        /// <returns>The instance of <see cref="TracerBuilder"/> to chain the calls.</returns>
+        public static TracerBuilder UseJaeger(this TracerBuilder builder, Action<JaegerExporterOptions> configure, Action<SpanProcessorPipelineBuilder> processorConfigure)
+        {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (configure == null)
+            {
+                throw new ArgumentNullException(nameof(configure));
+            }
+
+            if (processorConfigure == null)
+            {
+                throw new ArgumentNullException(nameof(processorConfigure));
+            }
+
+            var options = new JaegerExporterOptions();
+            configure(options);
+            return builder.AddProcessorPipeline(b =>
+            {
+                b.SetExporter(new JaegerTraceExporter(options));
+                processorConfigure.Invoke(b);
+            });
+        }
+    }
+}