Module org.praxislive.core
Package org.praxislive.core

Interface ThreadContext

public interface ThreadContext
An optional context available from the Root lookup, providing the ability to query whether code is running on the Root thread, and to pass tasks to invoke on the Root thread.

  • Method Summary

    Modifier and Type
    Method
    Description
    default <T> T
    invoke(Callable<T> task)
    Invoke the passed in task on the calling thread, taking any required locks or other resources.
    void
    invokeLater(Runnable task)
    Execute a task on the Root thread.
    boolean
    isInUpdate()
    Check whether the current thread is the active thread executing inside a Root update.
    boolean
    isRootThread()
    Check whether the current thread is the thread currently driving a Root implementation.
    default boolean
    supportsDirectInvoke()
    Check whether the ThreadContext implementation supports direct invocation using invoke(java.util.concurrent.Callable).

  • Method Details

    • isInUpdate

      boolean isInUpdate()
      Check whether the current thread is the active thread executing inside a Root update.
      Returns:
      current thread is in Root update

    • isRootThread

      boolean isRootThread()
      Check whether the current thread is the thread currently driving a Root implementation. This is a looser check than isInUpdate() where a Root implementation may be driven by an external context - eg. UI event thread. It will always return true when isInUpdate() returns true. This method does not return true if a thread has been returned to a pool. As a guide, it will return true if blocking the current thread would block the Root from executing.
      Returns:
      current thread is Root executing thread

    • invokeLater

      void invokeLater(Runnable task)
      Execute a task on the Root thread. The task should carefully check that its state is still valid - eg. a component should check that it has not been removed from the Root hierarchy.
      Parameters:
      task - task to be executed

    • supportsDirectInvoke

      default boolean supportsDirectInvoke()
      Check whether the ThreadContext implementation supports direct invocation using invoke(java.util.concurrent.Callable). The default implementation returns false.
      Returns:
      true if direct invocation is supported

    • invoke

      default <T> T invoke(Callable<T> task) throws Exception
      Invoke the passed in task on the calling thread, taking any required locks or other resources. This method should be used with caution when absolutely necessary. Callers should check the method is supported via supportsDirectInvoke().

      The default implementation throws UnsupportedOperationException, even when isInUpdate() is true and it is therefore safe for the caller to directly execute the task.

      Type Parameters:
      T - generic type of task
      Parameters:
      task - task to invoke
      Returns:
      result of task
      Throws:
      UnsupportedOperationException - if direct invoke not supported
      Exception - from execution of underlying task