thread-utils.c

#include "git-compat-util.h"
#include "thread-utils.h"

#if defined(hpux) || defined(__hpux) || defined(_hpux)
#  include <sys/pstat.h>
#endif

/*
 * By doing this in two steps we can at least get
 * the function to be somewhat coherent, even
 * with this disgusting nest of #ifdefs.
 */
#ifndef _SC_NPROCESSORS_ONLN
#  ifdef _SC_NPROC_ONLN
#    define _SC_NPROCESSORS_ONLN _SC_NPROC_ONLN
#  elif defined _SC_CRAY_NCPU
#    define _SC_NPROCESSORS_ONLN _SC_CRAY_NCPU
#  endif
#endif

int online_cpus(void)
{
#ifdef NO_PTHREADS
	return 1;
#else
#ifdef _SC_NPROCESSORS_ONLN
	long ncpus;
#endif

#ifdef GIT_WINDOWS_NATIVE
	DWORD len = 0;
	if (!GetLogicalProcessorInformationEx(RelationProcessorCore, NULL, &len) && GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
		uint8_t *buf = malloc(len);
		if (buf) {
			if (GetLogicalProcessorInformationEx(RelationProcessorCore, (PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX) buf, &len)) {
				DWORD offset = 0;
				int n_cores = 0;
				while (offset < len) {
					PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX info = (PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX) (buf + offset);
					offset += info->Size;
					/* The threads within a core always share a single group. We need to count the bits in the mask to get a thread count. */
					for (KAFFINITY mask = info->Processor.GroupMask[0].Mask; mask; mask >>= 1)
						n_cores += mask &1;
				}
				if (n_cores) {
					free(buf);
					return n_cores;
				}
			}
			free(buf);
		}
	}
#elif defined(hpux) || defined(__hpux) || defined(_hpux)
	struct pst_dynamic psd;

	if (!pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0))
		return (int)psd.psd_proc_cnt;
#elif defined(HAVE_BSD_SYSCTL) && defined(HW_NCPU)
	int mib[2];
	size_t len;
	int cpucount;

	mib[0] = CTL_HW;
#  ifdef HW_AVAILCPU
	mib[1] = HW_AVAILCPU;
#  elif defined(HW_NCPUONLINE)
	mib[1] = HW_NCPUONLINE;
#  else
	mib[1] = HW_NCPU;
#  endif /* HW_AVAILCPU */
	len = sizeof(cpucount);
	if (!sysctl(mib, 2, &cpucount, &len, NULL, 0))
		return cpucount;
#endif /* defined(HAVE_BSD_SYSCTL) && defined(HW_NCPU) */

#ifdef _SC_NPROCESSORS_ONLN
	if ((ncpus = (long)sysconf(_SC_NPROCESSORS_ONLN)) > 0)
		return (int)ncpus;
#endif

	return 1;
#endif
}

int init_recursive_mutex(pthread_mutex_t *m)
{
#ifndef NO_PTHREADS
	pthread_mutexattr_t a;
	int ret;

	ret = pthread_mutexattr_init(&a);
	if (!ret) {
		ret = pthread_mutexattr_settype(&a, PTHREAD_MUTEX_RECURSIVE);
		if (!ret)
			ret = pthread_mutex_init(m, &a);
		pthread_mutexattr_destroy(&a);
	}
	return ret;
#else
	return 0;
#endif
}

#ifdef NO_PTHREADS
int dummy_pthread_create(pthread_t *pthread, const void *attr,
			 void *(*fn)(void *), void *data)
{
	/*
	 * Do nothing.
	 *
	 * The main purpose of this function is to break compiler's
	 * flow analysis and avoid -Wunused-variable false warnings.
	 */
	return ENOSYS;
}

int dummy_pthread_init(void *data)
{
	/*
	 * Do nothing.
	 *
	 * The main purpose of this function is to break compiler's
	 * flow analysis or it may realize that functions like
	 * pthread_mutex_init() is no-op, which means the (static)
	 * variable is not used/initialized at all and trigger
	 * -Wunused-variable
	 */
	return ENOSYS;
}

int dummy_pthread_join(pthread_t pthread, void **retval)
{
	/*
	 * Do nothing.
	 *
	 * The main purpose of this function is to break compiler's
	 * flow analysis and avoid -Wunused-variable false warnings.
	 */
	return ENOSYS;
}

#endif