1 // Copyright 2017, OpenCensus Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package trace_test 16 17 import ( 18 "context" 19 "fmt" 20 21 "go.opencensus.io/trace" 22 ) 23 24 // This example shows how to use StartSpan and (*Span).End to capture 25 // a function execution in a Span. It assumes that the function 26 // has a context.Context argument. 27 func ExampleStartSpan() { 28 printEvens := func(ctx context.Context) { 29 ctx, span := trace.StartSpan(ctx, "my/package.Function") 30 defer span.End() 31 32 for i := 0; i < 10; i++ { 33 if i%2 == 0 { 34 fmt.Printf("Even!\n") 35 } 36 } 37 } 38 39 ctx := context.Background() 40 printEvens(ctx) 41 } 42