Interface SpawnChildSetupFunc

All Superinterfaces:
FunctionPointer
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface @Generated("org.javagi.JavaGI") public interface SpawnChildSetupFunc extends FunctionPointer

Functional interface declaration of the SpawnChildSetupFunc callback.

See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    run(@Nullable MemorySegment data)
    Specifies the type of the setup function passed to g_spawn_async(), g_spawn_sync() and g_spawn_async_with_pipes(), which can, in very limited ways, be used to affect the child's execution.
    default MemorySegment
    toCallback(Arena arena)
    Creates a native function pointer to the upcall(MemorySegment) method.
    default void
    upcall(MemorySegment data)
    The upcall method is called from native code.

  • Method Details

    • run

      void run(@Nullable MemorySegment data)

      Specifies the type of the setup function passed to g_spawn_async(), g_spawn_sync() and g_spawn_async_with_pipes(), which can, in very limited ways, be used to affect the child's execution.

      On POSIX platforms, the function is called in the child after GLib has performed all the setup it plans to perform, but before calling exec(). Actions taken in this function will only affect the child, not the parent.

      On Windows, the function is called in the parent. Its usefulness on Windows is thus questionable. In many cases executing the child setup function in the parent can have ill effects, and you should be very careful when porting software to Windows that uses child setup functions.

      However, even on POSIX, you are extremely limited in what you can safely do from a GSpawnChildSetupFunc, because any mutexes that were held by other threads in the parent process at the time of the fork() will still be locked in the child process, and they will never be unlocked (since the threads that held them don't exist in the child). POSIX allows only async-signal-safe functions (see signal(7)) to be called in the child between fork() and exec(), which drastically limits the usefulness of child setup functions.

      In particular, it is not safe to call any function which may call malloc(), which includes POSIX functions such as setenv(). If you need to set up the child environment differently from the parent, you should use g_get_environ(), g_environ_setenv(), and g_environ_unsetenv(), and then pass the complete environment list to the g_spawn... function.

      Parameters:
      data - user data passed to the function.

    • upcall

      default void upcall(MemorySegment data)
      The upcall method is called from native code. The parameters are marshaled and run(MemorySegment) is executed.

    • toCallback

      default MemorySegment toCallback(Arena arena)
      Creates a native function pointer to the upcall(MemorySegment) method.
      Specified by:
      toCallback in interface FunctionPointer
      Parameters:
      arena - the arena in which the function pointer is allocated
      Returns:
      the native function pointer