| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.solr.util.tracing; |
| |
| import javax.servlet.http.HttpServletRequest; |
| import java.util.Random; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import io.opentracing.SpanContext; |
| import io.opentracing.Tracer; |
| import io.opentracing.noop.NoopTracerFactory; |
| import io.opentracing.propagation.Format; |
| |
| public class GlobalTracer { |
| private static final Tracer NOOP_TRACER = NoopTracerFactory.create(); |
| private static final Random RANDOM; |
| static { |
| // We try to make things reproducible in the context of our tests by initializing the random instance |
| // based on the current seed |
| String seed = System.getProperty("tests.seed"); |
| if (seed == null) { |
| RANDOM = new Random(); |
| } else { |
| RANDOM = new Random(seed.hashCode()); |
| } |
| } |
| |
| private static volatile GlobalTracer INS = new GlobalTracer(NOOP_TRACER); |
| |
| public synchronized static void setup(Tracer tracer) { |
| if (INS != null) { |
| INS.close(); |
| } |
| INS = new GlobalTracer(tracer); |
| } |
| |
| public static GlobalTracer get() { |
| return INS; |
| } |
| |
| public static Tracer getTracer() { |
| return INS.tracer(); |
| } |
| |
| @VisibleForTesting |
| final Tracer tracer; |
| private double rate; |
| private final ThreadLocal<Tracer> threadLocal = new ThreadLocal<>(); |
| |
| public GlobalTracer(Tracer tracer) { |
| this.tracer = tracer; |
| } |
| |
| public synchronized void setSamplePercentage(double rate) { |
| this.rate = rate / 100.0; |
| } |
| |
| @VisibleForTesting |
| public double getSampleRate() { |
| return rate; |
| } |
| |
| public boolean tracing() { |
| return threadLocal.get() != null |
| && threadLocal.get() != NOOP_TRACER |
| && threadLocal.get().activeSpan() != null; |
| } |
| |
| public SpanContext extract(HttpServletRequest request) { |
| SpanContext spanContext = tracer.extract(Format.Builtin.HTTP_HEADERS, new HttpServletCarrier(request)); |
| if (spanContext != null) { |
| threadLocal.set(tracer); |
| } |
| return spanContext; |
| } |
| |
| private Tracer tracer() { |
| Tracer tracer = threadLocal.get(); |
| if (tracer != null) |
| return tracer; |
| |
| if (traced()) { |
| threadLocal.set(this.tracer); |
| } else { |
| threadLocal.set(NOOP_TRACER); |
| } |
| |
| return threadLocal.get(); |
| } |
| |
| /** |
| * Clear tracing context for the current thread |
| */ |
| public void clearContext() { |
| threadLocal.remove(); |
| } |
| |
| private boolean traced() { |
| return RANDOM.nextDouble() <= rate; |
| } |
| |
| public void close() { |
| tracer.close(); |
| } |
| } |