Package io.micrometer.context

Interface ContextAccessor<READ,WRITE>

Type Parameters:

READ - type of context for reading

WRITE - type of context for writing

public interface ContextAccessor<READ,WRITE>

Contract to assist with access to an external, map-like context, such as the Project Reactor Context, including the ability to read values from it a Map and to write values to it from a Map.

Since:

1.0.0

Method Summary

Modifier and Type	Method	Description
Class<? extends READ>	readableType()	Class representing the type of context this accessor is capable of reading values from.
<T> @Nullable T	readValue(READ sourceContext, Object key)	Read a single value from the source context.
void	readValues(READ sourceContext, Predicate<Object> keyPredicate, Map<Object,Object> readValues)	Read values from a source context into a Map.
Class<? extends WRITE>	writeableType()	Class representing the type of context this accessor can restore values to.
WRITE	writeValues(Map<Object,Object> valuesToWrite, WRITE targetContext)	Write values from a Map to a target context.

Method Details

readableType

Class<? extends READ> readableType()

Class representing the type of context this accessor is capable of reading values from.

readValues

void readValues(READ sourceContext,
 Predicate<Object> keyPredicate,
 Map<Object,Object> readValues)

Read values from a source context into a Map.

Parameters:

sourceContext - the context to read from; the context type should be assignable from the type returned by readableType().

When an ContextAccessor is used to populate a ContextSnapshot, the snapshot implementations are required to filter out null mappings, so it is not required to implement special handling in the accessor.

keyPredicate - a predicate to decide which keys to read

readValues - a map where to put read values

readValue

<T> @Nullable T readValue(READ sourceContext,
 Object key)

Read a single value from the source context.

Parameters:

sourceContext - the context to read from; the context type should be assignable from the type returned by readableType().

key - the key to use to look up the context value

Returns:

the value, if present

writeableType

Class<? extends WRITE> writeableType()

Class representing the type of context this accessor can restore values to.

writeValues

WRITE writeValues(Map<Object,Object> valuesToWrite,
 WRITE targetContext)

Write values from a Map to a target context.

Parameters:

valuesToWrite - the values to write to the target context.

targetContext - the context to write to; the context type should be assignable from the type returned by writeableType().

Returns:

a context with the written values