Ohh, I see now, thank you so much Ken!
Best,
Tamas
> On 15 Apr 2016, at 11:57, Ken Thomases <k...@codeweavers.com> wrote:
>
> On Apr 15, 2016, at 4:34 AM, Tamas Nagy <tamas.lov.n...@gmail.com> wrote:
>>
>> I have an ongoing project where I’m using a CFMessagePort some sort of IPC
>> communication. The CFMessagePort has a callback, something like this:
>>
>> static CFDataRef Callback(CFMessagePortRef port,
>> SInt32 messageID,
>> CFDataRef data,
>> void *info)
>> {
>> return CFBridgingRetain([NSArchiver
>> archivedDataWithRootObject:[(__bridge AppDelegate *)info getParameters]]);
>> }
>>
>> The Callback runs on the main queue, it has been setup with
>> CFMessagePortSetDispatchQueue(localPort, dispatch_get_main_queue());
>>
>> The interesting part is, and I don’t know why is this happening,
>> CFBridgingRetain does not leak memory here - checked out with Instruments,
>> also let the app run for a couple of hours, and memory usage does not
>> increased (check out in Activity Monitor). Should not that CFBridgingRetain
>> leak memory in this example, since I’m retaining a CF object and not
>> releasing it by CFRelease?
>
> No, there's no leak.
>
> Traditionally, memory management in Core Foundation does not use an
> autorelease mechanism. (There is now a CFAutorelease() function, but that
> doesn't play into the Core Foundation memory management conventions.) So, if
> a function needs to return a new or otherwise untracked object, what are its
> options? It can't release it before it returns it. It may not get an
> opportunity to release it "some time later". It has to return ownership to
> the caller.
>
> The caller of your callback is expecting to receiving ownership and takes
> responsibility for releasing the object it receives. In fact, the
> documentation for CFMessagePortCallBack says, "The system releases the
> returned CFData object."
> <https://developer.apple.com/library/mac/documentation/CoreFoundation/Reference/CFMessagePortRef/#//apple_ref/c/tdef/CFMessagePortCallBack>
>
> So, your code is doing the right thing.
>
> Regards,
> Ken
>
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