Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

System Functions (n - p) pthread_once(2)
On systems running H06.24 or later H-series RVUs or J06.13 or later J-series RVUs, you can use
the POSIX User Thread Model library with 32-bit or 64-bit threaded applications.
To use this function in a 32-bit threaded application that uses the POSIX User Thread Model
library on systems running H06.24 or later RVUs or J06.13 or later RVUs, perform the same
tasks (described above) used to enable the POSIX User Thread Model library on systems running
H06.21/J06.10 or later RVUs.
To use this function in a 64-bit threaded application that uses the POSIX User Thread Model
library on systems running H06.24 or later RVUs or J06.13 or later RVUs, you must perform all
of the following tasks:
• Include the pthread.h header file in the application.
• Compile the application using the _PUT_MODEL_ feature test macro or equivalent
compiler command option.
• Compile the application using the -Wlp64 compiler command option.
• Link the application to the yputdll library (/G/system/zdllnnn/yputdll).
To use this function in a threaded application that uses the Standard POSIX Threads library on
systems running H06.21 or later RVUs or J06.10 or later RVUs, you must perform all of the fol-
lowing tasks:
• Include the spthread.h header file in the application.
• Compile the application using the _SPT_MODEL_ feature test macro or equivalent
compiler command option.
• Link the application to the zsptdll library (/G/system/zdllnnn/zsptdll).
NOTES
If you specify a routine that directly or indirectly results in a recursive call to pthread_once()
and that specifies the same routine argument, the recursive call can result in a deadlock.
EXAMPLES
RETURN VALUES
If an error condition occurs, this function returns an integer value indicating the type of error.
Possible return values are:
0 Successful completion.
[EINVAL] The value specified for the once_control parameter is not valid.
STANDARDS CONFORMANCE
Interfaces documented on this reference page conform to the following industry standards:
• IEEE Std 1003.1-2004, POSIX System Application Program Interface
The use of the header file spthread.h is an HP exception to the POSIX standard.
527186-023 Hewlett-Packard Company 5−163