Package brave.propagation

Class ThreadLocalCurrentTraceContext

java.lang.Object

brave.propagation.CurrentTraceContext

brave.propagation.ThreadLocalCurrentTraceContext

Direct Known Subclasses:

CurrentTraceContext.Default

public class ThreadLocalCurrentTraceContext
extends CurrentTraceContext

In-process trace context propagation backed by a static thread local.

Design notes

A static thread local ensures we have one context per thread, as opposed to one per thread- tracer. This means all tracer instances will be able to see any tracer's contexts.

The trade-off of this (instance-based reference) vs the reverse: trace contexts are not separated by tracer by default. For example, to make a trace invisible to another tracer, you have to use a non-default implementation.

Sometimes people make different instances of the tracer just to change configuration like the local service name. If we used a thread-instance approach, none of these would be able to see eachother's scopes. This would break Tracing.currentTracer() scope visibility in a way few would want to debug. It might be phrased as "MySQL always starts a new trace and I don't know why."

If you want a different behavior, use a different subtype of CurrentTraceContext, possibly your own, or raise an issue and explain what your use case is.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ThreadLocalCurrentTraceContext.Builder

Nested classes/interfaces inherited from class brave.propagation.CurrentTraceContext

CurrentTraceContext.Default, CurrentTraceContext.Scope, CurrentTraceContext.ScopeDecorator

Method Summary

Modifier and Type	Method	Description
void	clear()	This component is backed by a possibly static shared thread local.
static CurrentTraceContext	create()
TraceContext	get()	Returns the current span in scope or null if there isn't one.
static ThreadLocalCurrentTraceContext.Builder	newBuilder()
CurrentTraceContext.Scope	newScope(TraceContext currentSpan)	Sets the current span in scope until the returned object is closed.

Methods inherited from class brave.propagation.CurrentTraceContext

decorateScope, executor, executorService, maybeScope, wrap, wrap

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

create

public static CurrentTraceContext create()

newBuilder

public static ThreadLocalCurrentTraceContext.Builder newBuilder()

clear

public void clear()

This component is backed by a possibly static shared thread local. Call this to clear the reference when you are sure any residual state is due to a leak. This is generally only useful in tests.

Since:

5.11

get

public TraceContext get()

Description copied from class: CurrentTraceContext

Returns the current span in scope or null if there isn't one.

Specified by:

get in class CurrentTraceContext

newScope

public CurrentTraceContext.Scope newScope(@Nullable TraceContext currentSpan)

Description copied from class: CurrentTraceContext

Sets the current span in scope until the returned object is closed. It is a programming error to drop or never close the result. Using try-with-resources is preferred for this reason.

Specified by:

newScope in class CurrentTraceContext

Parameters:

currentSpan - span to place into scope or null to clear the scope