diff --git a/sdk/trace/sampling.go b/sdk/trace/sampling.go index 736752367da..4f91d4d95c6 100644 --- a/sdk/trace/sampling.go +++ b/sdk/trace/sampling.go @@ -77,3 +77,11 @@ func NeverSample() Sampler { return SamplingDecision{Sample: false} } } + +// AlwaysParentSample returns a Sampler that samples a trace only +// if the parent span is sampled. +// This Sampler is a passthrough to the ProbabilitySampler with +// a fraction of value 0. +func AlwaysParentSample() Sampler { + return ProbabilitySampler(0) +} diff --git a/sdk/trace/sampling_test.go b/sdk/trace/sampling_test.go new file mode 100644 index 00000000000..488bfe946ef --- /dev/null +++ b/sdk/trace/sampling_test.go @@ -0,0 +1,49 @@ +// Copyright 2020, 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 ( + "testing" + + "go.opentelemetry.io/otel/api/core" + sdktrace "go.opentelemetry.io/otel/sdk/trace" +) + +func TestAlwaysParentSampleWithParentSampled(t *testing.T) { + sampler := sdktrace.AlwaysParentSample() + traceID, _ := core.TraceIDFromHex("4bf92f3577b34da6a3ce929d0e0e4736") + spanID, _ := core.SpanIDFromHex("00f067aa0ba902b7") + parentCtx := core.SpanContext{ + TraceID: traceID, + SpanID: spanID, + TraceFlags: core.TraceFlagsSampled, + } + if !sampler(sdktrace.SamplingParameters{ParentContext: parentCtx}).Sample { + t.Error("Sampling decision should be true") + } +} + +func TestAlwaysParentSampleWithParentNotSampled(t *testing.T) { + sampler := sdktrace.AlwaysParentSample() + traceID, _ := core.TraceIDFromHex("4bf92f3577b34da6a3ce929d0e0e4736") + spanID, _ := core.SpanIDFromHex("00f067aa0ba902b7") + parentCtx := core.SpanContext{ + TraceID: traceID, + SpanID: spanID, + } + if sampler(sdktrace.SamplingParameters{ParentContext: parentCtx}).Sample { + t.Error("Sampling decision should be false") + } +}