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[libc++] Remove sysctl-based implementation of thread::hardware_concurrency() 

Using sysctl requires including headers that are considered internal on
Linux, like <sys/sysctl.h> & friends. Instead, sysconf is defined by POSIX
(and we have a fallback for Windows), so all the systems we support should
be happy with just sysconf.

Differential Revision: https://reviews.llvm.org/D92135
This commit is contained in:
Louis Dionne 2020-11-25 16:42:42 -05:00
parent d7ca140c01
commit 3d7f19ff18
1 changed files with 2 additions and 20 deletions
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22
libcxx/src/thread.cpp
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@ -15,20 +15,8 @@
#include "future" #include "future"
#include "limits" #include "limits"
#if __has_include(<sys/types.h>)
# include <sys/types.h>
#endif
#if __has_include(<sys/param.h>)
# include <sys/param.h>
#endif
#if __has_include(<sys/sysctl.h>)
# include <sys/sysctl.h>
#endif
#if __has_include(<unistd.h>) #if __has_include(<unistd.h>)
# include <unistd.h> # include <unistd.h> // for sysconf
#endif #endif
#if defined(__NetBSD__) #if defined(__NetBSD__)
@ -84,13 +72,7 @@ thread::detach()
unsigned unsigned
thread::hardware_concurrency() _NOEXCEPT thread::hardware_concurrency() _NOEXCEPT
{ {
#if defined(CTL_HW) && defined(HW_NCPU) #if defined(_SC_NPROCESSORS_ONLN)
unsigned n;
int mib[2] = {CTL_HW, HW_NCPU};
std::size_t s = sizeof(n);
sysctl(mib, 2, &n, &s, 0, 0);
return n;
#elif defined(_SC_NPROCESSORS_ONLN)
long result = sysconf(_SC_NPROCESSORS_ONLN); long result = sysconf(_SC_NPROCESSORS_ONLN);
// sysconf returns -1 if the name is invalid, the option does not exist or // sysconf returns -1 if the name is invalid, the option does not exist or
// does not have a definite limit. // does not have a definite limit.