[vlc-devel] [PATCH v2 2/2] os2: implement vlc_once()

[KO Myung-Hun]

Hi/2.

Sorry for the late reply, first.

Romain Vimont wrote:
> On Tue, Apr 24, 2018 at 07:06:15PM +0900, KO Myung-Hun wrote:
>> Ping ?
>>
>> KO Myung-Hun wrote:
>>> ---
>>>  include/vlc_threads.h |  6 ++++++
>>>  src/os2/thread.c      | 18 ++++++++++++++++++
>>>  2 files changed, 24 insertions(+)
>>>
>>> diff --git a/include/vlc_threads.h b/include/vlc_threads.h
>>> index 37054a3ded..b7505da266 100644
>>> --- a/include/vlc_threads.h
>>> +++ b/include/vlc_threads.h
>>> @@ -125,6 +125,12 @@ typedef struct
>>>  #define VLC_STATIC_COND { NULLHANDLE, 0, NULLHANDLE, 0 }
>>>  #define LIBVLC_NEED_SEMAPHORE
>>>  #define LIBVLC_NEED_RWLOCK
>>> +typedef struct
>>> +{
>>> +    unsigned done;
> 
> The atomic_load_explicit() argument must point to an atomic type:
> <http://en.cppreference.com/w/c/atomic/atomic_load>
> <http://en.cppreference.com/w/c/language/atomic>
> <https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/com.ibm.zos.v2r1.cbclx01/atomic_integ.htm>
> 

Ok.

>>> +    vlc_mutex_t mutex;
>>> +} vlc_once_t;
>>> +#define VLC_STATIC_ONCE { 0, VLC_STATIC_MUTEX }
>>>  typedef struct vlc_threadvar *vlc_threadvar_t;
>>>  typedef struct vlc_timer *vlc_timer_t;
>>>  
>>> diff --git a/src/os2/thread.c b/src/os2/thread.c
>>> index 3ecf24dc0d..9f64fcc3b3 100644
>>> --- a/src/os2/thread.c
>>> +++ b/src/os2/thread.c
>>> @@ -38,6 +38,7 @@
>>>  #include <limits.h>
>>>  #include <errno.h>
>>>  #include <time.h>
>>> +#include <stdatomic.h>
>>>  
>>>  #include <sys/types.h>
>>>  #ifdef HAVE_SYS_SOCKET_H
>>> @@ -429,6 +430,23 @@ int vlc_cond_timedwait_daytime (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
>>>      return vlc_cond_wait_common (p_condvar, p_mutex, ulTimeout);
>>>  }
>>>  
>>> +void vlc_once(vlc_once_t *once, void (*cb)(void))
>>> +{
>>> +    if( atomic_load_explicit( &once->done, memory_order_acquire ) == 0 )
>>> +    {
>>> +        vlc_mutex_lock( &once->mutex );
>>> +
>>> +        if( atomic_load_explicit( &once->done, memory_order_acquire ) == 0 )
>>> +        {
>>> +            cb();
>>> +
>>> +            atomic_store_explicit( &once->done, 1, memory_order_release );
>>> +        }
>>> +
>>> +        vlc_mutex_unlock( &once->mutex );
>>> +    }
>>> +}
> 
> Once "once" (twice?) uses an atomic type, vlc_once() looks good to me.
> 

Unfortunately, if using _Atomic keyword, vlc_once_t cannot be used on
C++ because _Atomic is not a keyword on C++.

After all, I think, atomic functions provided by kLIBC should be used
not ones from C11.

Any idea ?

>>> +
>>>  /*** Thread-specific variables (TLS) ***/
>>>  struct vlc_threadvar
>>>  {
>>
>> -- 
>> KO Myung-Hun
>>
>> Using Mozilla SeaMonkey 2.7.2
>> Under OS/2 Warp 4 for Korean with FixPak #15
>> In VirtualBox v4.1.32 on Intel Core i7-3615QM 2.30GHz with 8GB RAM
>>
>> Korean OS/2 User Community : http://www.os2.kr/
>>
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-- 
KO Myung-Hun

Using Mozilla SeaMonkey 2.7.2
Under OS/2 Warp 4 for Korean with FixPak #15
In VirtualBox v4.1.32 on Intel Core i7-3615QM 2.30GHz with 8GB RAM

Korean OS/2 User Community : http://www.os2.kr/