On 26 Apr 2018, at 12:09, Serge Stinckwich <serge.stinckwich@gmail.com> wrote:

On Wed, Apr 25, 2018 at 11:07 PM, Ben Coman <btc@openinworld.com> wrote:

On 25 April 2018 at 23:08, Serge Stinckwich <serge.stinckwich@gmail.com> wrote:
I don't understand the default

finalizeResourceData: handle
    handle isNull ifTrue: [ ^ self ].
    handle free.
    handle beNull

when handle is an ExternaData, free is defined as in ExternalStructure class as:

free
    "Free the handle pointed to by the receiver"
    (handle ~~ nil and:[handle isExternalAddress]) ifTrue:[handle free].
    handle := nil.

Theorectical side thought. I wonder how threadsafe that code for #free is?
Sending two messages between the ~~nil test and nil-assignment
seems to leave the door open for another thread to erroneously pass the ~~nil test.

IIUC, with an inlined #ifNotNil, the following might be safer (?)

  free
  "Save handle so its nil assignment is inlined with its #ifNotNil: test, eliminating possible thread change during message sends"
  |savedhandle|
  handle ifNotNil: [
  savedHandle := handle.
  handle := nil.
  savedHandle isExternalAddress ifTrue: [ savedHandle  free].
  ].

��You don't reply to my original question, Ben :-)

I have another concern with UFFI !

When I call ffiCall: and the call returns an Opaque Object, an instance of this Opaque object is created, but apparently,
basicNew is called instead of new on the class. What is the ��

��intention behind ?��

basicNew ensures the object is created ��virgin��, since its contents will depend on what comes from outside and not in Pharo.

you can then call initialize by yourself if needed, as it happens for example in AthensCairoSurface>>extent:format:

Esteban