Module io.smallrye.mutiny
Package io.smallrye.mutiny

Class Context

java.lang.Object
io.smallrye.mutiny.Context
public final class Context extends Object
A context allows sharing key / value entries along with a subscriber in a Mutiny pipeline, so all operators can share implicit data for a given subscription.

A context is provided by a UniSubscriber or Flow.Subscriber that implements ContextSupport.

Context keys are represented as String while values can be from heterogeneous types.

Context instances are thread-safe. Internal storage is not allocated until the first entry is being added.

Contexts shall be primarily used to share transient data used for networked I/O processing such as correlation identifiers, tokens, etc. They should not be used as general-purpose data structures that are frequently updated and that hold large amounts of data.

See Also:

  • Method Details

    • empty

      public static Context empty()
      Creates a new empty context.
      Returns:
      the context

    • of

      public static Context of(Object... entries)
      Creates a context from key / value pairs.
      Parameters:
      entries - a sequence of key / value pairs, as in key1, value1, key2, value2
      Returns:
      the new context
      Throws:
      IllegalArgumentException - when entries is not balanced
      NullPointerException - when entries is null

    • from

      public static Context from(Map<String,?> entries)
      Creates a context by copying the entries from a Map.
      Parameters:
      entries - the map, cannot be null
      Returns:
      the new context
      Throws:
      NullPointerException - when entries is null

    • contains

      public boolean contains(String key)
      Checks whether the context has an entry for a given key.
      Parameters:
      key - the key
      Returns:
      true when there is an entry for key, false otherwise

    • get

      public <T> T get(String key) throws NoSuchElementException
      Get a value for a key.
      Type Parameters:
      T - the value type
      Parameters:
      key - the key
      Returns:
      the value
      Throws:
      NoSuchElementException - when there is no entry for key

    • getOrElse

      public <T> T getOrElse(String key, Supplier<? extends T> alternativeSupplier)
      Get a value for a key, or provide an alternative value when not present.
      Type Parameters:
      T - the value type
      Parameters:
      key - the key
      alternativeSupplier - the alternative value supplier when there is no entry for key
      Returns:
      the value

    • put

      public Context put(String key, Object value)
      Stores a value for a given key.
      Parameters:
      key - the key
      value - the value, cannot be null
      Returns:
      this context

    • delete

      public Context delete(String key)
      Delete an entry for a given key, if present.
      Parameters:
      key - the key
      Returns:
      this context

    • isEmpty

      public boolean isEmpty()
      Test whether the context is empty.
      Returns:
      true if the context is empty, false otherwise

    • keys

      public Set<String> keys()
      Gives the set of keys present in the context at the time the method is being called.

      Note that each call to this method produces a copy.

      Returns:
      the set of keys

    • equals

      public boolean equals(Object other)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object