fix compiling errors on AIX

[lisr]

What

spdlog failed to compile on AIX 7.2

In file included from /~/spdlog/src/spdlog.cpp:12:
/~/spdlog/include/spdlog/details/os-inl.h:237:16: error: expected unqualified-id
    int fd = ::fileno(f);
               ^
/usr/include/stdio.h:515:25: note: expanded from macro 'fileno'
#define fileno(__p)     ((__p)->_file)
                        ^
In file included from /~spdlog/src/spdlog.cpp:12:
/~/spdlog/include/spdlog/details/os-inl.h:340:34: error: no member named 'pthread_getthreadid_np' in the global namespace
    return static_cast<size_t>(::pthread_getthreadid_np());
                               ~~^
1 warning and 2 errors generated.

with following configurations

export OBJECT_MODE=64
cmake .. -DCMAKE_C_COMPILER=xlclang -DCMAKE_CXX_COMPILER=xlclang++ -DCMAKE_POSITION_INDEPENDENT_CODE=ON

Code Change

• fileno is a macro on AIX, so we cannot use :: scope decorator for this function.
• AIX use pthread_self + pthread_getthrds_np instead of pthread_getthreadid_np See AIX Doc

Environment

# xlclang++ --version
IBM XL C/C++ for AIX, V16.1.0  (5725-C72, 5765-J12)
Version: 16.01.0000.0009

System Model: IBM,9119-MHE
Machine Serial Number: 10D945P
Processor Type: PowerPC_POWER8
Processor Implementation Mode: POWER 8
Processor Version: PV_8_Compat
Number Of Processors: 2
Processor Clock Speed: 4024 MHz
CPU Type: 64-bit
Kernel Type: 64-bit
LPAR Info: 24 paix871
Memory Size: 8192 MB
Good Memory Size: 8192 MB
Platform Firmware level: SC860_226
Firmware Version: IBM,FW860.90 (SC860_226)
Console Login: enable
Auto Restart: true
Full Core: false
NX Crypto Acceleration: Capable and Enabled
In-Core Crypto Acceleration: Capable, but not Enabled

[gabime]

The doc states that pthread_getthreadid_np() is much far better for our needs:

“
The pthread_self() function does NOT return the integral thread of the calling thread. You must use pthread_getthreadid_np() to return an integral identifier for the thread.

If your code requires the unique integer identifier for the calling thread often, or in a loop, the pthread_getthreadid_np() function can provide significant performance improvements over the combination of pthread_self(), and pthread_getunique_np() calls that provide equivalent behavior.
“

[lisr]

Hi @gabime , The doc link you referred to is for IBM i 7.3, not AIX, both AIX 7.2 and future AIX 7.3 do not support pthread_getthreadid_np for now.

I've made a new commit to use pthread_getthrds_np in our case https://www.ibm.com/docs/en/aix/7.2?topic=p-pthread-getthrds-np-subroutine

pthread_getthrds_np gives a more meaningful id like this:

[20:38:38 -05:00] [I] [thread 25297381] This an info message with custom format

it's better than pthread_getunique_np (which was deprecated on AIX https://www.ibm.com/docs/en/aix/7.2?topic=p-pthread-getunique-np-subroutine)

This subroutine is not POSIX compliant and is provided only for compatibility with DCE threads. It should not be used when writing new applications.

[gabime]

Thanks for clarifying.It would be interesting to perform a quick bench for this implementation:

mkdir build && cd build && cmake -DSPDLOG_BUILD_BENCH=1 ..
cd bench && ./formatter-bench %t

[lisr]

On same aforementioned AIX environment, here is the command line to compile

export OBJECT_MODE=64
mkdir build && cd build && cmake -DCMAKE_C_COMPILER=xlclang -DCMAKE_CXX_COMPILER=xlclang++ -DSPDLOG_BUILD_BENCH=1 ..
make
cd bench && ./formatter-bench %t

and this is the output:

bash-5.1# cd bench && ./formatter-bench %t
failed to open /proc/cpuinfo
2021-11-20T09:46:40+00:00
Running ./formatter-bench
Run on (-1 X 512.016 MHz CPU )
***WARNING*** Library was built as DEBUG. Timings may be affected.
-----------------------------------------------------
Benchmark           Time             CPU   Iterations
-----------------------------------------------------
%t               62.1 ns         62.0 ns     11136364

BTW, I just pushed another commit as the async_bench.cpp failed to compile on AIX due to:

~~/spdlog/bench/async_bench.cpp:163:12: error: reference to 'thread' is ambiguous
    vector<thread> threads;
           ^
/usr/include/sys/thread.h:106:8: note: candidate found by name lookup is 'thread'
struct  thread {
        ^
/opt/IBM/xlC/16.1.0/include2/c++/thread:301:24: note: candidate found by name lookup is 'std::__1::thread'
class _LIBCPP_TYPE_VIS thread
                       ^
~~/spdlog/bench/async_bench.cpp:163:12: error: reference to 'thread' is ambiguous
    vector<thread> threads;
           ^
/usr/include/sys/thread.h:106:8: note: candidate found by name lookup is 'thread'
struct  thread {
        ^
/opt/IBM/xlC/16.1.0/include2/c++/thread:301:24: note: candidate found by name lookup is 'std::__1::thread'
class _LIBCPP_TYPE_VIS thread
                       ^

[gabime]

Merged. Thanks @lisr