Module brave

Package brave.internal

Class PropagationFields<K,V>

java.lang.Object

brave.internal.PropagationFields<K,V>

Direct Known Subclasses:

MapPropagationFields, PredefinedPropagationFields

public abstract class PropagationFields<K,V>
extends java.lang.Object

We need to retain propagation state extracted from headers. However, we don't know the trace identifiers, yet. In order to resolve this ordering concern, we create an object to hold extra state, and defer associating it with a span ID (via ExtraFactory.decorate(TraceContext).

Implementations of this type should use copy-on-write semantics to prevent changes in a child context from affecting its parent.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	PropagationFields.FieldConsumer<K,V>

Constructor Summary

Constructors

Constructor	Description
PropagationFields()

Method Summary

Modifier and Type	Method	Description
abstract void	forEach(PropagationFields.FieldConsumer<K,V> consumer)	Invokes the consumer for every non-null field value
static <K,V> V	get(TraceContext context, K key, java.lang.Class<? extends PropagationFields<K,V>> type)	Returns the value of the field with the specified key or null if not available
abstract V	get(K key)	Returns the value of the field with the specified key or null if not available
abstract boolean	isEmpty()
static <K,V> void	put(TraceContext context, K key, V value, java.lang.Class<? extends PropagationFields<K,V>> type)	Replaces the value of the field with the specified key, ignoring if not a permitted field
abstract void	put(K key, V value)	Replaces the value of the field with the specified key, ignoring if not a permitted field
protected abstract java.util.Map<K,V>	toMap()	for testing and default toString
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

PropagationFields

public PropagationFields()

Method Detail

get

public abstract V get(K key)

Returns the value of the field with the specified key or null if not available

put

public abstract void put(K key,
                         V value)

Replaces the value of the field with the specified key, ignoring if not a permitted field

forEach

public abstract void forEach(PropagationFields.FieldConsumer<K,V> consumer)

Invokes the consumer for every non-null field value

isEmpty

public abstract boolean isEmpty()

toMap

protected abstract java.util.Map<K,V> toMap()

for testing and default toString

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

get

public static <K,V> V get(TraceContext context,
                                K key,
                                java.lang.Class<? extends PropagationFields<K,V>> type)

Returns the value of the field with the specified key or null if not available

put

public static <K,V> void put(TraceContext context,
                                   K key,
                                   V value,
                                   java.lang.Class<? extends PropagationFields<K,V>> type)

Replaces the value of the field with the specified key, ignoring if not a permitted field