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.exporter.trace.logging.LoggingTraceExporter; 22 import io.opencensus.trace.Span; 23 import io.opencensus.trace.Tracer; 24 import io.opencensus.trace.Tracing; 25 import io.opencensus.trace.config.TraceConfig; 26 import io.opencensus.trace.samplers.Samplers; 27 28 /** Example showing how to directly create a child {@link Span} and add annotations. */ 29 public final class MultiSpansTracing { 30 // Per class Tracer. 31 private static final Tracer tracer = Tracing.getTracer(); 32 MultiSpansTracing()33 private MultiSpansTracing() {} 34 doWork()35 private static void doWork() { 36 Span rootSpan = tracer.spanBuilderWithExplicitParent("MyRootSpan", null).startSpan(); 37 rootSpan.addAnnotation("Annotation to the root Span before child is created."); 38 Span childSpan = tracer.spanBuilderWithExplicitParent("MyChildSpan", rootSpan).startSpan(); 39 childSpan.addAnnotation("Annotation to the child Span"); 40 childSpan.end(); 41 rootSpan.addAnnotation("Annotation to the root Span after child is ended."); 42 rootSpan.end(); 43 } 44 45 /** 46 * Main method. 47 * 48 * @param args the main arguments. 49 */ main(String[] args)50 public static void main(String[] args) { 51 52 // WARNING: Be careful before you set sampler value to always sample, especially in 53 // production environment. Trace data is often very large in size and is expensive to 54 // collect. This is why rather than collecting traces for every request(i.e. alwaysSample), 55 // downsampling is prefered. 56 // 57 // By default, OpenCensus provides a probabilistic sampler that will trace once in every 58 // 10,000 requests, that's why if default probabilistic sampler is used 59 // you might not see trace data printed or exported and this is expected behavior. 60 61 TraceConfig traceConfig = Tracing.getTraceConfig(); 62 traceConfig.updateActiveTraceParams( 63 traceConfig.getActiveTraceParams().toBuilder().setSampler(Samplers.alwaysSample()).build()); 64 65 LoggingTraceExporter.register(); 66 doWork(); 67 68 // Wait for a duration longer than reporting duration (5s) to ensure spans are exported. 69 // Spans are exported every 5 seconds 70 sleep(5100); 71 } 72 } 73