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.putLocal(CustomLocal.KEY, new CustomLocal(...));
Author:
Julien Viet

  • Method Details

    • 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.