Request for review (M): 7132070: Use a mach_port_t as the OSThread thread_id rather than pthread_t on BSD/OSX

[Paul Hohensee]

On 2/15/12 1:58 PM, Staffan Larsen wrote:
> On 15 feb 2012, at 19:49, Paul Hohensee wrote:
>
>> Also,
>>
>> You can move the #include of mach.h into globalDefinitions_gcc.hpp,
>> in the #ifdef __APPLE__ section.  That way, it won't cause a compile-
>> time error on non-osx platforms that don't have it.
> I dislike adding more stuff to globalDefinitions since that gets pulled in all over the place. I'd prefer to have #includes only where they are needed.

globalDefinitions_gcc.hpp is where these sorts of #includes currently live,
so I'd go with present practice rather than doing something new.  If
you want to put the include of mach.h in os_bsd.inline.hpp, then you
should do something similar with all the platform-dependent includes
in globalDefinitions_gcc.hpp.

>
>> The declaration of _thread_id, thread_id() and set_thread_id() in os_bsd.hpp
>> can be put under a #ifdef __APPLE__, vis.,
>>
>> #ifdef _ALLBSD_SOURCE
>> #ifdef __APPLE__
>>   thread_t _thread_id;
>> #else
>>   pthread_t _thread_id;
>> #endif
>> #endif
>>
>> The uses of mach_thread_self() in os_bsd.cpp can be similarly conditioned.
>>
>> If there's a thread_t defined by non-osx bsd implementations, then
>> you don't need predication in os_bsd.hpp, though you'd still need it
>> in os_bsd.cpp.  I'm assuming there's no mach_thread_self() on non-osx
>> bsd platforms.
> I could do that, but the question is how much work we should put into not trying to break something that we can't test anyway. There's no way, even if I do this that I can verify that it works.

Even so, if we ever need to make hotspot work on non-osx bsd platforms, 
we'll
at least have markers to guide the work.

Paul

>
> /Staffan
>
>> Thanks,
>>
>> Paul
>>
>> On 2/15/12 1:33 PM, Paul Hohensee wrote:
>>> Imo we should at least try to make non-osx bsd builds work, since
>>> the original code did work for non-osx builds.  This change doesn't
>>> do that.
>>>
>>> In globalDefinitions_gcc.hpp, if you keep the lines
>>>
>>> #undef ELF_AC
>>> #undef EFL_ID
>>>
>>> then you don't have to change vm_version_x86.hpp.
>>>
>>> Paul
>>>
>>> On 2/15/12 10:16 AM, Daniel D. Daugherty wrote:
>>>> The _ALLBSD_SOURCE symbol is defined by the HotSpot Makefile infrastructure.
>>>> It is used to identify code specific to the BSD family of OSes.
>>>> The __APPLE__ symbol is defined by the Apple compiler(s) and it is used to
>>>> identify code specific to MacOS X.
>>>>
>>>> Typically you'll see something like:
>>>>
>>>> #ifdef _ALLBSD_SOURCE
>>>>
>>>> <code that works on all BSDs>
>>>>
>>>> #ifdef __APPLE__
>>>> <code specific to MacOS X>
>>>> #else
>>>> <code for other BSDs>
>>>> #endif // __APPLE__
>>>> #endif // _ALLBSD_SOURCE
>>>>
>>>> As for building on non-MacOS X BSDs, that would be nice, but we
>>>> don't have the infrastructure to do it.
>>>>
>>>> Dan
>>>>
>>>> On 2/15/12 6:57 AM, Mikael Gerdin wrote:
>>>>> Hi Staffan,
>>>>>
>>>>> It looks like you're adding Mac-specific stuff like thread_t and calls to ::mach_thread_self() inside _ALLBSD_SOURCE #ifdefs, are you sure this won't break BSD builds?
>>>>> Does the OSX compiler define _ALLBSD_SOURCE or is that for (free|net|open)bsd?
>>>>> It's too bad we don't do regular builds on any of the BSDs, otherwise this would have been easier to figure out.
>>>>>
>>>>> /Mikael
>>>>>
>>>>>
>>>>> On 2012-02-15 11:29, Staffan Larsen wrote:
>>>>>> Please review the following change:
>>>>>>
>>>>>> Bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7132070
>>>>>>
>>>>>> Webrev: http://cr.openjdk.java.net/~sla/7132070/webrev.00/
>>>>>>
>>>>>> This changes the value returned by OSThread::thread_id() and
>>>>>> os::current_thread_id() on macosx to return the mach thread_t instead of
>>>>>> pthread_t. There is a separate method OSThread:pthread_id() that returns
>>>>>> the pthread_t.
>>>>>>
>>>>>> The reason for this change is both that JFR would like a 4 byte value
>>>>>> for thread id, and that SA requires access to the thread_t.
>>>>>>
>>>>>> Thanks,
>>>>>> /Staffan