SDK: span processor interface and simple span processor. (#117)

* SDK: SpanProcessor Interface.

* add simple span processor.

* rename span processor.

* fix logic to export or process span data.

sdk/trace/simple_span_processor_test.go

@@ -0,0 +1,77 @@
+// Copyright 2019, 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 trace_test
+
+import (
+	"context"
+	"testing"
+
+	"go.opentelemetry.io/api/core"
+	apitrace "go.opentelemetry.io/api/trace"
+	sdktrace "go.opentelemetry.io/sdk/trace"
+)
+
+type testExporter struct {
+	spans []*sdktrace.SpanData
+}
+
+func (t *testExporter) ExportSpan(s *sdktrace.SpanData) {
+	t.spans = append(t.spans, s)
+}
+
+var _ sdktrace.Exporter = (*testExporter)(nil)
+
+func init() {
+	sdktrace.Register()
+	sdktrace.ApplyConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()})
+}
+
+func TestNewSimpleSpanProcessor(t *testing.T) {
+	ssp := sdktrace.NewSimpleSpanProcessor(&testExporter{})
+	if ssp == nil {
+		t.Errorf("Error creating new instance of SimpleSpanProcessor\n")
+	}
+}
+
+func TestNewSimpleSpanProcessorWithNilExporter(t *testing.T) {
+	ssp := sdktrace.NewSimpleSpanProcessor(nil)
+	if ssp == nil {
+		t.Errorf("Error creating new instance of SimpleSpanProcessor with nil Exporter\n")
+	}
+}
+
+func TestSimpleSpanProcessorOnEnd(t *testing.T) {
+	te := testExporter{}
+	ssp := sdktrace.NewSimpleSpanProcessor(&te)
+	if ssp == nil {
+		t.Errorf("Error creating new instance of SimpleSpanProcessor with nil Exporter\n")
+	}
+	sdktrace.RegisterSpanProcessor(ssp)
+	tid := core.TraceID{High: 0x0102030405060708, Low: 0x0102040810203040}
+	sid := uint64(0x0102040810203040)
+	sc := core.SpanContext{
+		TraceID:      tid,
+		SpanID:       sid,
+		TraceOptions: 0x1,
+	}
+	_, span := apitrace.GlobalTracer().Start(context.Background(), "OnEnd", apitrace.ChildOf(sc))
+	span.Finish()
+
+	wantTraceID := tid
+	gotTraceID := te.spans[0].SpanContext.TraceID
+	if wantTraceID != gotTraceID {
+		t.Errorf("SimplerSpanProcessor OnEnd() check: got %+v, want %+v\n", gotTraceID, wantTraceID)
+	}
+}