Package io.micrometer.context.integration

Class Slf4jThreadLocalAccessor

java.lang.Object

io.micrometer.context.integration.Slf4jThreadLocalAccessor

All Implemented Interfaces:

ThreadLocalAccessor<Map<String,String>>

public class Slf4jThreadLocalAccessor
extends Object
implements ThreadLocalAccessor<Map<String,String>>

ThreadLocalAccessor for copying contents of the MDC across Thread boundaries. It can work with selected keys only or copy the entire contents of the MDC. It is recommended to use only when no other ThreadLocalAccessor interacts with the MDC or the selected keys, for instance tracing libraries.

Since:

1.1.1

Field Summary

Fields

Modifier and Type	Field	Description
static final String	KEY	Key under which this accessor is registered in ContextRegistry.

Constructor Summary

Constructors

Constructor	Description
Slf4jThreadLocalAccessor(String... keys)	Create an instance of Slf4jThreadLocalAccessor.

Method Summary

Modifier and Type	Method	Description
@Nullable Map<String,String>	getValue()	Return the current ThreadLocal value.
Object	key()	The key to associate with the ThreadLocal value when saved within a ContextSnapshot.
void	setValue()	Called instead of ThreadLocalAccessor.setValue(Object) in order to remove the current ThreadLocal value at the start of a ContextSnapshot.Scope.
void	setValue(Map<String,String> value)	Set the ThreadLocal at the start of a ContextSnapshot.Scope to a value obtained from a ContextSnapshot or from a different type of context (through a ContextAccessor).

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.micrometer.context.ThreadLocalAccessor

reset, restore, restore

Field Details

KEY

public static final String KEY

Key under which this accessor is registered in ContextRegistry.

See Also:

• Constant Field Values

Constructor Details

Slf4jThreadLocalAccessor

public Slf4jThreadLocalAccessor(String... keys)

Create an instance of Slf4jThreadLocalAccessor.

Parameters:

keys - selected keys for which values from the MDC should be propagated across Thread boundaries. If none provided, the entire contents of the MDC are propagated.

Method Details

key

public Object key()

Description copied from interface: ThreadLocalAccessor

The key to associate with the ThreadLocal value when saved within a ContextSnapshot.

Specified by:

key in interface ThreadLocalAccessor<Map<String,String>>

getValue

public @Nullable Map<String,String> getValue()

Description copied from interface: ThreadLocalAccessor

Return the current ThreadLocal value.

This method is called in two scenarios:

• When capturing a ContextSnapshot. A null value is ignored and the ThreadLocalAccessor.key() will not be present in the snapshot.
• When setting ThreadLocal values from a ContextSnapshot or from a Context object (through a ContextAccessor) to save existing values in order to ThreadLocalAccessor.restore(Object) them at the end of the scope. A null value means the ThreadLocal should not be set and upon closing a ContextSnapshot.Scope, the ThreadLocalAccessor.restore() variant is called.

Specified by:

getValue in interface ThreadLocalAccessor<Map<String,String>>

setValue

public void setValue(Map<String,String> value)

Description copied from interface: ThreadLocalAccessor

Set the ThreadLocal at the start of a ContextSnapshot.Scope to a value obtained from a ContextSnapshot or from a different type of context (through a ContextAccessor).

Specified by:

setValue in interface ThreadLocalAccessor<Map<String,String>>

Parameters:

value - the value to set, never null when called from a ContextSnapshot implementation, which is not allowed to store mappings to null.

setValue

public void setValue()

Description copied from interface: ThreadLocalAccessor

Called instead of ThreadLocalAccessor.setValue(Object) in order to remove the current ThreadLocal value at the start of a ContextSnapshot.Scope.

Specified by:

setValue in interface ThreadLocalAccessor<Map<String,String>>