On 15/04/2013 4:55 PM, Rickard Bäckman wrote:
David,

any new thoughts?

Not a new one but I think factoring into Semaphore.hpp/cpp and using a few ifdefs is better than three versions of the Semaphore class. The signal thread could use it also.

David

Thanks
/R

On Apr 12, 2013, at 8:06 AM, Rickard Bäckman wrote:


On Apr 12, 2013, at 7:34 AM, David Holmes wrote:

On 12/04/2013 3:01 PM, Rickard Bäckman wrote:

On Apr 12, 2013, at 1:04 AM, David Holmes wrote:

On 11/04/2013 11:02 PM, Rickard Bäckman wrote:
On Apr 11, 2013, at 2:39 PM, David Holmes wrote:
So what did you mean about pthread_semaphore (what is that anyway?) ??

Never mind, pthread condition variables.

Ah I see.


I really, really, really don't like seeing three versions of this class :( 
Can't BSD and Linux at least share a POSIX version? (And I wonder if we can 
actually mix-n-match UI threads on Solaris with POSIX semaphores on Solaris?)

I don't like it either, our OS code isn't really helpful when it comes do reusing 
things :) Not sure how I would layout things to make them only available on BSD (Not 
Mac) and Linux. I guess os_posix.hpp with lots of #ifdefs, but I'm not sure I"m 
feeling that happy about that.

Why would the os_posix version need a lot of ifdefs?

Well, I guess we would need:

(in ifdef pseudo language)

#ifdef (LINUX || (BSD && !APPLE))
…
#endif

But if it isn't "posix" then we won't be building os_posix - right?

Linux, Solaris, Bsd & Mac builds and include os_posix. They are all "implementing 
posix" we are just not using the same semaphore implementation on all of them.


The second interesting problem this will get us into is that sem_t is not declared in 
this context. Where do we put the #include <semaphore.h>? Impossible in 
os_posix.hpp since it is included in the middle of a class definition. I could put it 
in os.hpp in the #ifdef path that does the jvm_platform.h includes, not sure if that 
is very pretty either.

Semaphores are already used by the signal handler thread - semaphore.h is 
included in os_linux.cpp etc, so why would os_posix be any different ?

But couldn't we just have a Semaphore.h/cpp with any needed ifdefs?

Do we really have four versions:
- linux (posix)
- BSD (posix)
- Solaris
- Mac (different to BSD?)


3:
1) linux & bsd uses the sem_ interface
2) solaris uses the sema_ interface
3) mac uses the semaphore_ interface

Okay but if mac is BSD why can't we use bsd ie posix interface instead of the 
mach semaphore_ ?

Because apple decided not to implement sem_timedwait.
On Solaris we use sema_ because sem_ requires us to link with -lrt which we 
currently don't (and I'm not really feeling like adding it)



BTW I like the idea of using the semaphore, we're just haggling on the details. 
;-)

I'm fine with that :)

/R


Thanks,
David

/R

??

David
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