mirror of https://github.com/status-im/consul.git
54 lines
2.0 KiB
Go
54 lines
2.0 KiB
Go
// Copyright 2017, OpenCensus 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 contains support for OpenCensus distributed tracing.
|
|
|
|
The following assumes a basic familiarity with OpenCensus concepts.
|
|
See http://opencensus.io
|
|
|
|
|
|
Exporting Traces
|
|
|
|
To export collected tracing data, register at least one exporter. You can use
|
|
one of the provided exporters or write your own.
|
|
|
|
trace.RegisterExporter(exporter)
|
|
|
|
By default, traces will be sampled relatively rarely. To change the sampling
|
|
frequency for your entire program, call ApplyConfig. Use a ProbabilitySampler
|
|
to sample a subset of traces, or use AlwaysSample to collect a trace on every run:
|
|
|
|
trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
|
|
|
|
Be careful about using trace.AlwaysSample in a production application with
|
|
significant traffic: a new trace will be started and exported for every request.
|
|
|
|
Adding Spans to a Trace
|
|
|
|
A trace consists of a tree of spans. In Go, the current span is carried in a
|
|
context.Context.
|
|
|
|
It is common to want to capture all the activity of a function call in a span. For
|
|
this to work, the function must take a context.Context as a parameter. Add these two
|
|
lines to the top of the function:
|
|
|
|
ctx, span := trace.StartSpan(ctx, "example.com/Run")
|
|
defer span.End()
|
|
|
|
StartSpan will create a new top-level span if the context
|
|
doesn't contain another span, otherwise it will create a child span.
|
|
*/
|
|
package trace // import "go.opencensus.io/trace"
|