io.micrometer.tracing.ThreadLocalSpan Maven / Gradle / Ivy
/**
* Copyright 2022 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 io.micrometer.tracing;
import java.util.ArrayDeque;
/**
* Represents a {@link Span} stored in thread local.
*
* @author Marcin Grzejszczak
* @since 1.0.0
*/
public class ThreadLocalSpan {
private final ThreadLocal> currentSpanInScopeStack = new ThreadLocal<>();
private final Tracer tracer;
/**
* Creates a new instance of {@link ThreadLocalSpan}.
* @param tracer tracer
*/
public ThreadLocalSpan(Tracer tracer) {
this.tracer = tracer;
}
/**
* Sets given span and scope.
* @param span - span to be put in scope
*/
public void set(Span span) {
Tracer.SpanInScope spanInScope = this.tracer.withSpan(span);
SpanAndScope newSpanAndScope = new SpanAndScope(span, spanInScope);
getCurrentSpanInScopeStack().addFirst(newSpanAndScope);
}
/**
* Returns the currently stored span and scope.
* @return span and scope
*/
public SpanAndScope get() {
return getCurrentSpanInScopeStack().peekFirst();
}
/**
* Removes the current span from thread local and brings back the previous span to the
* current thread local.
* @return removed span of {@code null} if there was none
*/
public SpanAndScope remove() {
SpanAndScope spanAndScope = getCurrentSpanInScopeStack().pollFirst();
if (spanAndScope == null) {
return null;
}
if (spanAndScope.getScope() != null) {
spanAndScope.getScope().close();
}
return spanAndScope;
}
private ArrayDeque getCurrentSpanInScopeStack() {
ArrayDeque stack = this.currentSpanInScopeStack.get();
if (stack == null) {
stack = new ArrayDeque<>();
this.currentSpanInScopeStack.set(stack);
}
return stack;
}
}