[Vm-dev] socketRecordSize is probably not 64-bit friendly

[David T. Lewis]

>  Hi David,
>
> On Sun, Mar 22, 2015 at 11:43 AM, David T. Lewis <lewis at mail.msen.com>
> wrote:
>
>>
>> On Sun, Mar 22, 2015 at 11:27:05AM -0700, Eliot Miranda wrote:
>> >
>> > Hi David,
>> >
>> > On Mar 22, 2015, at 10:58 AM, "David T. Lewis" <lewis at mail.msen.com>
>> wrote:
>> >
>> > >
>> > > On Sun, Mar 22, 2015 at 05:04:12PM +0100, Nicolas Cellier wrote:
>> > >>
>> > >> Hi,
>> > >> I noticed that SocketPlugin>>socketRecordSize was so defined:
>> > >> socketRecordSize
>> > >>    "Return the size of a Smalltalk socket record in bytes."
>> > >>
>> > >>    ^ self cCode: 'sizeof(SQSocket)' inSmalltalk: [12]
>> > >>
>> > >>
>> > >> Shouldn't it have been like its brothers in OSProcessPlugin and
>> AioPlugin:
>> > >>
>> > >> socketRecordSize
>> > >>    "Return the size of a Smalltalk socket record in bytes."
>> > >>
>> > >>    ^ self cCode: 'sizeof(SQSocket)' inSmalltalk: [Smalltalk
>> wordSize
>> * 3]
>> > >>
>> > >>
>> > >> I presume we don't use self sizeof: because the Smalltalk side does
>> not
>> > >> have any idea of what a SQSocket is... (an opaque struct/handle)
>> > >
>> > > On my machine, sizeof(SQSocket) is 16 for both 32 bits and 64 bits.
>> I
>> would
>> > > have expected it to be 12 for the 32-bit case, but maybe the
>> compiler
>> is
>> > > aligning it differently for some reason.
>> > >
>> > > In any case, "Smalltalk wordSize * 3" would not be right, because
>> the
>> > > actual data structure is this:
>> > >
>> > >    typedef struct
>> > >    {
>> > >      int   sessionID;
>> > >      int   socketType;  /* 0 = TCP, 1 = UDP */
>> > >      void  *privateSocketPtr;
>> > >    }  SQSocket, *SocketPtr;
>> > >
>> > >
>> > > In order to cover the common cases, it might be best to just change
>> > > the implementation to this:
>> > >
>> > >     ^ self cCode: 'sizeof(SQSocket)' inSmalltalk: [16]
>> >
>> > No, no and thrice no!  :). It should /always/ be written
>> >
>> >      ^self sizeof: #SQSocket
>> >
>> > and the size answered in a sizeof: implementation marked
>> <doNotGenerate>.  That way
>> > - there is one def not one in potentially multiple clients
>> > - you don't even need the sizeOfSQSocket method in the first place.
>> >
>> > Please see VMMaker.oscog
>> >
>>
>> Ok.
>>
>> I note for the record that SocketPlugin>>socketRecordSize has a time
>> stamp
>> of 2/22/2000 ;-)
>>
>
> :)
>
> Please find a version of the AioPlugin that has this change attached.  I
> can't commit to the repo.  I hope you'll find it fit to upload yourself :)
> --

Thanks Eliot,

I'll update it as soon as I can (probably tomorrow night).

Dave