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} using scoped Spans, install it in the current 31 * context, and add annotations. 32 */ 33 public final class MultiSpansScopedTracing { 34 // Per class Tracer. 35 private static final Tracer tracer = Tracing.getTracer(); 36 MultiSpansScopedTracing()37 private MultiSpansScopedTracing() {} 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 try (Scope ss = tracer.spanBuilder("MyChildSpan").startScopedSpan()) { 46 doSomeOtherWork(); 47 } 48 } 49 doWork()50 private static void doWork() { 51 tracer.getCurrentSpan().addAnnotation("Annotation to the root Span before child is created."); 52 doSomeMoreWork(); 53 tracer.getCurrentSpan().addAnnotation("Annotation to the root Span after child is ended."); 54 } 55 56 /** 57 * Main method. 58 * 59 * @param args the main arguments. 60 */ main(String[] args)61 public static void main(String[] args) { 62 63 // WARNING: Be careful before you set sampler value to always sample, especially in 64 // production environment. Trace data is often very large in size and is expensive to 65 // collect. This is why rather than collecting traces for every request(i.e. alwaysSample), 66 // downsampling is prefered. 67 // 68 // By default, OpenCensus provides a probabilistic sampler that will trace once in every 69 // 10,000 requests, that's why if default probabilistic sampler is used 70 // you might not see trace data printed or exported and this is expected behavior. 71 72 TraceConfig traceConfig = Tracing.getTraceConfig(); 73 traceConfig.updateActiveTraceParams( 74 traceConfig.getActiveTraceParams().toBuilder().setSampler(Samplers.alwaysSample()).build()); 75 76 LoggingTraceExporter.register(); 77 try (Scope ss = tracer.spanBuilderWithExplicitParent("MyRootSpan", null).startScopedSpan()) { 78 doWork(); 79 } 80 81 // Wait for a duration longer than reporting duration (5s) to ensure spans are exported. 82 // Spans are exported every 5 seconds 83 sleep(5100); 84 } 85 } 86