Package io.vertx.core.spi.context.storage

Interface ContextLocal<T>

public interface ContextLocal<T>

A local storage for arbitrary data attached to a Context.

Local storage should be registered before creating a Vertx instance, once registered a local storage cannot be unregistered.

It is recommended to initialize local storage as static fields of a VertxServiceProvider, since providers are discovered before the capture of known local storages.

 public class CustomLocal implements VertxServiceProvider {
   public static final ContextLocal<CustomLocal> KEY = ContextLocal.registerLocal(CustomLocal.class);
   ...
 }
 

Such provider must then be declared as a Java service provider in META/INF/services/io.vertx.core.spi.VertxServiceProvider and optionally in a module-info.java.

Context local can be used from a Vert.x Context with the following methods.

• Context.getLocal(ContextLocal)
• Context.getLocal(ContextLocal, Supplier)
• Context.putLocal(ContextLocal, Object)
• Context.removeLocal(ContextLocal)
• Context.getLocal(ContextLocal, AccessMode)
• Context.getLocal(ContextLocal, AccessMode, Supplier)
• Context.putLocal(ContextLocal, AccessMode, Object)
• Context.removeLocal(ContextLocal, AccessMode)

 context.putLocal(CustomLocal.KEY, new CustomLocal(...));
 

Author:

Julien Viet

Method Summary

Modifier and Type	Method	Description
default T	get(Context context)	Get the local data from the context.
default T	get(Context context, AccessMode accessMode)	Like get(Context) but with an accessMode.
default T	get(Context context, AccessMode accessMode, Supplier<? extends T> initialValueSupplier)	Like get(Context, Supplier) but with an accessMode.
default T	get(Context context, Supplier<? extends T> initialValueSupplier)	Get the local data from the context, when it does not exist then call initialValueSupplier to obtain the initial value.
default void	put(Context context, AccessMode accessMode, T value)	Like #put(Context, T) but with an accessMode.
default void	put(Context context, T data)	Put local data in the context.
static <T> ContextLocal<T>	registerLocal(Class<T> type)	Registers a context local storage.
static <T> ContextLocal<T>	registerLocal(Class<T> type, Function<T,T> duplicator)	Registers a context local storage.
default void	remove(Context context)	Remove the local data from the context.
default void	remove(Context context, AccessMode accessMode)	Like remove(Context) but with an accessMode.

Method Detail

registerLocal

static <T> ContextLocal<T> registerLocal(Class<T> type)

Registers a context local storage.

Returns:

the context local storage

registerLocal

static <T> ContextLocal<T> registerLocal(Class<T> type,
                                         Function<T,T> duplicator)

Registers a context local storage.

Returns:

the context local storage

get

default T get(Context context)

Get the local data from the context.

Returns:

the local data

get

default T get(Context context,
              Supplier<? extends T> initialValueSupplier)

Get the local data from the context, when it does not exist then call initialValueSupplier to obtain the initial value. The supplier can be called multiple times when several threads call this method concurrently.

Parameters:

initialValueSupplier - the supplier of the initial value

Returns:

the local data

put

default void put(Context context,
                 T data)

Put local data in the context.

Parameters:

data - the data

remove

default void remove(Context context)

Remove the local data from the context.

get

default T get(Context context,
              AccessMode accessMode)

Like get(Context) but with an accessMode.

get

default T get(Context context,
              AccessMode accessMode,
              Supplier<? extends T> initialValueSupplier)

Like get(Context, Supplier) but with an accessMode.

put

default void put(Context context,
                 AccessMode accessMode,
                 T value)

Like #put(Context, T) but with an accessMode.

remove

default void remove(Context context,
                    AccessMode accessMode)

Like remove(Context) but with an accessMode.