1 /* 2 * Copyright 2017, OpenCensus Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.opencensus.examples.trace; 18 19 import static io.opencensus.examples.trace.Utils.sleep; 20 21 import io.opencensus.common.Scope; 22 import io.opencensus.exporter.trace.logging.LoggingTraceExporter; 23 import io.opencensus.trace.Span; 24 import io.opencensus.trace.Tracer; 25 import io.opencensus.trace.Tracing; 26 import io.opencensus.trace.config.TraceConfig; 27 import io.opencensus.trace.samplers.Samplers; 28 29 /** 30 * Example showing how to create a child {@link Span}, install it to the current context and add 31 * annotations. 32 */ 33 public final class MultiSpansContextTracing { 34 // Per class Tracer. 35 private static final Tracer tracer = Tracing.getTracer(); 36 MultiSpansContextTracing()37 private MultiSpansContextTracing() {} 38 doSomeOtherWork()39 private static void doSomeOtherWork() { 40 tracer.getCurrentSpan().addAnnotation("Annotation to the child Span"); 41 } 42 doSomeMoreWork()43 private static void doSomeMoreWork() { 44 // Create a child Span of the current Span. 45 Span span = tracer.spanBuilder("MyChildSpan").startSpan(); 46 try (Scope ws = tracer.withSpan(span)) { 47 doSomeOtherWork(); 48 } 49 span.end(); 50 } 51 doWork()52 private static void doWork() { 53 tracer.getCurrentSpan().addAnnotation("Annotation to the root Span before child is created."); 54 doSomeMoreWork(); 55 tracer.getCurrentSpan().addAnnotation("Annotation to the root Span after child is ended."); 56 } 57 58 /** 59 * Main method. 60 * 61 * @param args the main arguments. 62 */ main(String[] args)63 public static void main(String[] args) { 64 65 // WARNING: Be careful before you set sampler value to always sample, especially in 66 // production environment. Trace data is often very large in size and is expensive to 67 // collect. This is why rather than collecting traces for every request(i.e. alwaysSample), 68 // downsampling is prefered. 69 // 70 // By default, OpenCensus provides a probabilistic sampler that will trace once in every 71 // 10,000 requests, that's why if default probabilistic sampler is used 72 // you might not see trace data printed or exported and this is expected behavior. 73 74 TraceConfig traceConfig = Tracing.getTraceConfig(); 75 traceConfig.updateActiveTraceParams( 76 traceConfig.getActiveTraceParams().toBuilder().setSampler(Samplers.alwaysSample()).build()); 77 78 LoggingTraceExporter.register(); 79 Span span = tracer.spanBuilderWithExplicitParent("MyRootSpan", null).startSpan(); 80 try (Scope ws = tracer.withSpan(span)) { 81 doWork(); 82 } 83 span.end(); 84 85 // Wait for a duration longer than reporting duration (5s) to ensure spans are exported. 86 // Spans are exported every 5 seconds 87 sleep(5100); 88 } 89 } 90