Package io.micrometer.observation.transport

Interface Propagator.Getter<C>

Type Parameters:

C - carrier of propagation fields, such as an http request.

Enclosing interface:

Propagator

public static interface Propagator.Getter<C>

Interface that allows to read propagated fields from a carrier.

Getter is stateless and allows to be saved as a constant to avoid runtime allocations.

Since:

1.10.0

Method Summary

Modifier and Type	Method	Description
@Nullable String	get(C carrier, String key)	Returns the first value of the given propagation key or returns null.
default Iterable<String>	getAll(C carrier, String key)	Get all values of the given propagation key, if any exist.

Method Details

get

@Nullable String get(C carrier,
 String key)

Returns the first value of the given propagation key or returns null. This method should be preferred over getAll(Object, String)} for better performance in cases where it is expected that the key is not repeated.

Parameters:

carrier - carrier of propagation fields, such as an http request.

key - the key of the field.

Returns:

the first value of the given propagation key or returns null.

getAll

default Iterable<String> getAll(C carrier,
 String key)

Get all values of the given propagation key, if any exist. This should only be used when it is expected that the key may be repeated. get(Object, String) should be preferred in other cases for performance.

Parameters:

carrier - carrier of propagation fields, such as an http request.

key - the key of the field.

Returns:

all values of the given propagation key or returns an empty Iterable if no values are found.

Since:

1.16.0

Implementation Note:

For backward-compatibility, a default implementation is provided that returns a list with the value of get(Object, String) or an empty list if no values are found. Implementors of this interface should override this method to provide an implementation that returns all present values of the given propagation key.