1 /* 2 * Copyright 2016-17, 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.trace; 18 19 import io.opencensus.common.Clock; 20 import io.opencensus.internal.ZeroTimeClock; 21 import io.opencensus.trace.config.TraceConfig; 22 import io.opencensus.trace.export.ExportComponent; 23 import io.opencensus.trace.propagation.PropagationComponent; 24 25 /** 26 * Class that holds the implementation instances for {@link Tracer}, {@link PropagationComponent}, 27 * {@link Clock}, {@link ExportComponent} and {@link TraceConfig}. 28 * 29 * <p>Unless otherwise noted all methods (on component) results are cacheable. 30 * 31 * @since 0.5 32 */ 33 public abstract class TraceComponent { 34 35 /** 36 * Returns the {@link Tracer} with the provided implementations. If no implementation is provided 37 * then no-op implementations will be used. 38 * 39 * @return the {@code Tracer} implementation. 40 * @since 0.5 41 */ getTracer()42 public abstract Tracer getTracer(); 43 44 /** 45 * Returns the {@link PropagationComponent} with the provided implementation. If no implementation 46 * is provided then no-op implementation will be used. 47 * 48 * @return the {@code PropagationComponent} implementation. 49 * @since 0.5 50 */ getPropagationComponent()51 public abstract PropagationComponent getPropagationComponent(); 52 53 /** 54 * Returns the {@link Clock} with the provided implementation. 55 * 56 * @return the {@code Clock} implementation. 57 * @since 0.5 58 */ getClock()59 public abstract Clock getClock(); 60 61 /** 62 * Returns the {@link ExportComponent} with the provided implementation. If no implementation is 63 * provided then no-op implementations will be used. 64 * 65 * @return the {@link ExportComponent} implementation. 66 * @since 0.5 67 */ getExportComponent()68 public abstract ExportComponent getExportComponent(); 69 70 /** 71 * Returns the {@link TraceConfig} with the provided implementation. If no implementation is 72 * provided then no-op implementations will be used. 73 * 74 * @return the {@link TraceConfig} implementation. 75 * @since 0.5 76 */ getTraceConfig()77 public abstract TraceConfig getTraceConfig(); 78 79 /** 80 * Returns an instance that contains no-op implementations for all the instances. 81 * 82 * @return an instance that contains no-op implementations for all the instances. 83 */ newNoopTraceComponent()84 static TraceComponent newNoopTraceComponent() { 85 return new NoopTraceComponent(); 86 } 87 88 private static final class NoopTraceComponent extends TraceComponent { 89 private final ExportComponent noopExportComponent = ExportComponent.newNoopExportComponent(); 90 91 @Override getTracer()92 public Tracer getTracer() { 93 return Tracer.getNoopTracer(); 94 } 95 96 @Override getPropagationComponent()97 public PropagationComponent getPropagationComponent() { 98 return PropagationComponent.getNoopPropagationComponent(); 99 } 100 101 @Override getClock()102 public Clock getClock() { 103 return ZeroTimeClock.getInstance(); 104 } 105 106 @Override getExportComponent()107 public ExportComponent getExportComponent() { 108 return noopExportComponent; 109 } 110 111 @Override getTraceConfig()112 public TraceConfig getTraceConfig() { 113 return TraceConfig.getNoopTraceConfig(); 114 } 115 NoopTraceComponent()116 private NoopTraceComponent() {} 117 } 118 } 119