forked from TrueCloudLab/lego
54 lines
2 KiB
Go
54 lines
2 KiB
Go
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// Copyright 2017, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/*
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Package trace contains support for OpenCensus distributed tracing.
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The following assumes a basic familiarity with OpenCensus concepts.
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See http://opencensus.io
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Exporting Traces
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To export collected tracing data, register at least one exporter. You can use
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one of the provided exporters or write your own.
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trace.RegisterExporter(exporter)
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By default, traces will be sampled relatively rarely. To change the sampling
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frequency for your entire program, call ApplyConfig. Use a ProbabilitySampler
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to sample a subset of traces, or use AlwaysSample to collect a trace on every run:
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trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
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Be careful about using trace.AlwaysSample in a production application with
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significant traffic: a new trace will be started and exported for every request.
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Adding Spans to a Trace
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A trace consists of a tree of spans. In Go, the current span is carried in a
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context.Context.
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It is common to want to capture all the activity of a function call in a span. For
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this to work, the function must take a context.Context as a parameter. Add these two
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lines to the top of the function:
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ctx, span := trace.StartSpan(ctx, "example.com/Run")
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defer span.End()
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StartSpan will create a new top-level span if the context
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doesn't contain another span, otherwise it will create a child span.
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*/
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package trace // import "go.opencensus.io/trace"
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