dsmiley commented on code in PR #1868: URL: https://github.com/apache/solr/pull/1868#discussion_r1310608641
########## solr/core/src/java/org/apache/solr/util/tracing/SimplePropagator.java: ########## @@ -0,0 +1,304 @@ +/* + * 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 io.opentracing.Scope; +import io.opentracing.ScopeManager; +import io.opentracing.Span; +import io.opentracing.SpanContext; +import io.opentracing.Tracer; +import io.opentracing.Tracer.SpanBuilder; +import io.opentracing.propagation.Format; +import io.opentracing.propagation.TextMap; +import io.opentracing.tag.Tag; +import io.opentracing.util.GlobalTracer; +import io.opentracing.util.ThreadLocalScopeManager; +import java.lang.invoke.MethodHandles; +import java.util.Collections; +import java.util.Iterator; +import java.util.Map; +import java.util.Map.Entry; +import java.util.concurrent.atomic.AtomicLong; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +public class SimplePropagator { + private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); + + private static final String TRACE_HOST_NAME = + System.getProperty("trace_host_name", System.getProperty("host")); + + static final String TRACE_ID = System.getProperty("TRACE_ID", "X-Trace-Id"); + + private static final AtomicLong traceCounter = new AtomicLong(0); + + public static void load() { + GlobalTracer.registerIfAbsent( + () -> { + log.info("Always-on trace id generation enabled."); + return new SimplePropagatorTracer(); + }); + } + + /** + * Tracer that only aims to do simple header propagation, tailored to how Solr works. + * + * <p>Heavily inspired from JaegerTracer, NoopTracer + */ + static class SimplePropagatorTracer implements Tracer { + + private final ScopeManager scopeManager = new ThreadLocalScopeManager(); + + @Override + public ScopeManager scopeManager() { + return scopeManager; + } + + @Override + public Span activeSpan() { + return scopeManager.activeSpan(); + } + + @Override + public Scope activateSpan(Span span) { + return scopeManager.activate(span); + } + + @Override + public SpanBuilder buildSpan(String operationName) { + return new SimplePropagatorSpanBuilder(scopeManager); + } + + @Override + public void close() {} + + @Override + public <C> void inject(SpanContext spanContext, Format<C> format, C carrier) { + if (!format.equals(Format.Builtin.HTTP_HEADERS)) { + throw new IllegalArgumentException("unsupported format " + format); + } + String traceId = spanContext.toTraceId(); + if (traceId != null && !traceId.isEmpty()) { + TextMap tm = (TextMap) carrier; + tm.put(TRACE_ID, traceId); + } + } + + @Override + public <C> SpanContext extract(Format<C> format, C carrier) { + if (!format.equals(Format.Builtin.HTTP_HEADERS)) { + throw new IllegalArgumentException("unsupported format " + format); + } + String traceId = null; + TextMap tm = (TextMap) carrier; + Iterator<Entry<String, String>> it = tm.iterator(); + while (it.hasNext()) { + var e = it.next(); + // 'equalsIgnoreCase' because header name might be lowercase + if (e.getKey().equalsIgnoreCase(TRACE_ID)) { + traceId = e.getValue(); + break; + } + } + if (traceId == null) { + traceId = newTraceId(); + } + return new SimplePropagatorSpanContext(traceId); + } + + @Override + public String toString() { + return "SimplePropagator"; + } + } + + private static final class SimplePropagatorSpanBuilder implements SpanBuilder { + + private final ScopeManager scopeManager; + // storing parent to support the parent being injected via the asChildOf method + private SpanContext parent; + + public SimplePropagatorSpanBuilder(ScopeManager scopeManager) { + this.scopeManager = scopeManager; + } + + @Override + public Span start() { + if (parent != null) { + return new SimplePropagatorSpan(parent); + } else if (scopeManager.activeSpan() != null) { + return new SimplePropagatorSpan(scopeManager.activeSpan().context()); Review Comment: This is going to be the common case as more spans show up _within_ Solr. Could SimplePropagatorSpan and SimplePropagatorSpanContext be combined into one? Create no new object; the context could *be* the span if all we are doing is propagation. I even wonder if we need a distinct builder? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@solr.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@solr.apache.org For additional commands, e-mail: issues-h...@solr.apache.org
