Move baggage and propagation to separate packages (#1325)

* Move propagation code to propagation package

* Move baggage code to baggage package

* Update changelog

* Make docs of baggage.Set more clear

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

propagation/trace_context_benchmark_test.go

@@ -0,0 +1,96 @@
+// 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.
+
+package propagation_test
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	"go.opentelemetry.io/otel/oteltest"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func BenchmarkInject(b *testing.B) {
+	var t propagation.TraceContext
+
+	injectSubBenchmarks(b, func(ctx context.Context, b *testing.B) {
+		req, _ := http.NewRequest("GET", "http://example.com", nil)
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			t.Inject(ctx, req.Header)
+		}
+	})
+}
+
+func injectSubBenchmarks(b *testing.B, fn func(context.Context, *testing.B)) {
+	b.Run("SampledSpanContext", func(b *testing.B) {
+		spanID, _ := trace.SpanIDFromHex("00f067aa0ba902b7")
+		traceID, _ := trace.TraceIDFromHex("4bf92f3577b34da6a3ce929d0e0e4736")
+
+		mockTracer := oteltest.DefaultTracer()
+		b.ReportAllocs()
+		sc := trace.SpanContext{
+			TraceID:    traceID,
+			SpanID:     spanID,
+			TraceFlags: trace.FlagsSampled,
+		}
+		ctx := trace.ContextWithRemoteSpanContext(context.Background(), sc)
+		ctx, _ = mockTracer.Start(ctx, "inject")
+		fn(ctx, b)
+	})
+
+	b.Run("WithoutSpanContext", func(b *testing.B) {
+		b.ReportAllocs()
+		ctx := context.Background()
+		fn(ctx, b)
+	})
+}
+
+func BenchmarkExtract(b *testing.B) {
+	extractSubBenchmarks(b, func(b *testing.B, req *http.Request) {
+		var propagator propagation.TraceContext
+		ctx := context.Background()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			propagator.Extract(ctx, req.Header)
+		}
+	})
+}
+
+func extractSubBenchmarks(b *testing.B, fn func(*testing.B, *http.Request)) {
+	b.Run("Sampled", func(b *testing.B) {
+		req, _ := http.NewRequest("GET", "http://example.com", nil)
+		req.Header.Set("traceparent", "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01")
+		b.ReportAllocs()
+
+		fn(b, req)
+	})
+
+	b.Run("BogusVersion", func(b *testing.B) {
+		req, _ := http.NewRequest("GET", "http://example.com", nil)
+		req.Header.Set("traceparent", "qw-00000000000000000000000000000000-0000000000000000-01")
+		b.ReportAllocs()
+		fn(b, req)
+	})
+
+	b.Run("FutureAdditionalData", func(b *testing.B) {
+		req, _ := http.NewRequest("GET", "http://example.com", nil)
+		req.Header.Set("traceparent", "02-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-09-XYZxsf09")
+		b.ReportAllocs()
+		fn(b, req)
+	})
+}