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/*
* Copyright 2013-2021 the original author or authors.
*
* Licensed 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
*
* https://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.springframework.cloud.sleuth.autoconfig.brave;
import brave.TracingCustomizer;
import brave.handler.SpanHandler;
import brave.sampler.Sampler;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.ConfigurationCondition;
import org.springframework.core.type.AnnotatedTypeMetadata;
/**
* Sleuth 1.x optimized for log-correlation only. Unless "spring-cloud-sleuth-zipkin" was
* present, the sampler defaulted to {@link Sampler#NEVER_SAMPLE}. This was to ensure the
* log only nodes never set the sampled flag.
*
*
* "spring-cloud-sleuth-zipkin" obviated the {@link Sampler#NEVER_SAMPLE} default by
* importing {@link SamplerConfiguration}. Nothing else did, so sampling properties were
* effectively ignored unless "spring-cloud-sleuth-zipkin" was in use, or something else
* similarly imported {@link SamplerConfiguration}.
*
*
* During a review of Wavefront integration, it was considered not correct to have other
* code import {@link SamplerConfiguration}. To avoid that, retain the old behaviour about
* log only nodes, and also not pin configuration to Zipkin involves a more complex
* condition.
*
*
* This condition looks for signs of non-default setup which likely requires sampling
* configuration. It passes on one of the following beans exist:
*
*
*
* - {@code zipkin2.reporter.Reporter} - what's used by Zipkin or others like
* Stackdriver
* - {@link SpanHandler} - only accepts sampled data
* - {@link TracingCustomizer} - can configure one of the above
*
*
*
* An integrated test that shows {@link Sampler#NEVER_SAMPLE} is default on fail exists in
* {@code TraceAutoConfigurationTests} intentionally, as users now needn't import
* {@link SamplerConfiguration} directly.
*/
final class SamplerCondition extends AnyNestedCondition {
SamplerCondition() {
super(ConfigurationPhase.REGISTER_BEAN);
}
// zipkin2.reporter.Reporter is in the classpath here, but technically it is optional
@ConditionalOnBean(type = "zipkin2.reporter.Reporter")
static final class ReporterAvailable {
}
@Conditional(SpanHandlerOtherThanCompositePresent.class)
static final class SpanHandlerAvailable {
}
@ConditionalOnBean(TracingCustomizer.class)
static final class TracingCustomizerAvailable {
}
static class SpanHandlerOtherThanCompositePresent extends SpringBootCondition implements ConfigurationCondition {
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
String[] spanHandlers = ((ListableBeanFactory) context.getBeanFactory())
.getBeanNamesForType(SpanHandler.class);
boolean moreThanSingleHandler = spanHandlers.length > 1;
if (moreThanSingleHandler) {
return ConditionOutcome.match("More than one handler present");
}
if (spanHandlers.length == 0) {
return ConditionOutcome.noMatch("No span handler is available");
}
// bean name is set in Brave bridge configuration
boolean singleCompositeSpanHandler = spanHandlers.length == 1
&& spanHandlers[0].equals("traceCompositeSpanHandler");
return singleCompositeSpanHandler ? ConditionOutcome.noMatch("Composite handler found")
: ConditionOutcome.match("Composite handler not found");
}
@Override
public ConfigurationPhase getConfigurationPhase() {
return ConfigurationPhase.REGISTER_BEAN;
}
}
}