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Use clock_gettime()'s CLOCK_REALTIME instead of gettimeofday().

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The system_clock::now() function currently uses gettimeofday(). The
problem with gettimeofday() is that it is an obsolete XSI function,
hence unavailable on CloudABI. See:

http://pubs.opengroup.org/onlinepubs/9699919799/functions/gettimeofday.html

Change this code to use clock_gettime() with CLOCK_REALTIME instead,
which is more consistent, as clock_gettime() is already used for
steady_clock.

A previous version of this change actually attempted to change
system_clock::duration, but I reverted this part as it breaks the
existing ABI.

Differential Revision:	http://reviews.llvm.org/D8253
Approved by:	jroelofs


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@237390 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ed Schouten 2015-05-14 20:54:18 +00:00
parent 56a8c6438a
commit 22a6d5aede
1 changed files with 40 additions and 24 deletions
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64
src/chrono.cpp
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@ -8,14 +8,21 @@
//===----------------------------------------------------------------------===//
#include "chrono"
#include <sys/time.h> //for gettimeofday and timeval
#ifdef __APPLE__
#include <mach/mach_time.h> // mach_absolute_time, mach_timebase_info_data_t
#else /* !__APPLE__ */
#include <cerrno> // errno
#include <system_error> // __throw_system_error
#include <time.h> // clock_gettime, CLOCK_MONOTONIC
#endif // __APPLE__
#include <time.h> // clock_gettime, CLOCK_MONOTONIC and CLOCK_REALTIME
#if !defined(CLOCK_REALTIME)
#include <sys/time.h> // for gettimeofday and timeval
#endif
#if !defined(_LIBCPP_HAS_NO_MONOTONIC_CLOCK) && !defined(CLOCK_MONOTONIC)
#if __APPLE__
#include <mach/mach_time.h> // mach_absolute_time, mach_timebase_info_data_t
#else
#error "Monotonic clock not implemented"
#endif
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
@ -29,9 +36,16 @@ const bool system_clock::is_steady;
system_clock::time_point
system_clock::now() _NOEXCEPT
{
#ifdef CLOCK_REALTIME
struct timespec tp;
if (0 != clock_gettime(CLOCK_REALTIME, &tp))
__throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");
return time_point(seconds(tp.tv_sec) + microseconds(tp.tv_nsec / 1000));
#else // !CLOCK_REALTIME
timeval tv;
gettimeofday(&tv, 0);
return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
#endif // CLOCK_REALTIME
}
time_t
@ -48,10 +62,26 @@ system_clock::from_time_t(time_t t) _NOEXCEPT
#ifndef _LIBCPP_HAS_NO_MONOTONIC_CLOCK
// steady_clock
//
// Warning: If this is not truly steady, then it is non-conforming. It is
// better for it to not exist and have the rest of libc++ use system_clock
// instead.
const bool steady_clock::is_steady;
#ifdef __APPLE__
#ifdef CLOCK_MONOTONIC
steady_clock::time_point
steady_clock::now() _NOEXCEPT
{
struct timespec tp;
if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
__throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
}
#elif defined(__APPLE__)
// mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of
// nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom
// are run time constants supplied by the OS. This clock has no relationship
@ -108,23 +138,9 @@ steady_clock::now() _NOEXCEPT
return time_point(duration(fp()));
}
#else // __APPLE__
// FIXME: if _LIBCPP_HAS_NO_MONOTONIC_CLOCK, then clock_gettime isn't going to
// work. It may be possible to fall back on something else, depending on the system.
// Warning: If this is not truly steady, then it is non-conforming. It is
// better for it to not exist and have the rest of libc++ use system_clock
// instead.
steady_clock::time_point
steady_clock::now() _NOEXCEPT
{
struct timespec tp;
if (0 != clock_gettime(CLOCK_MONOTONIC, &tp))
__throw_system_error(errno, "clock_gettime(CLOCK_MONOTONIC) failed");
return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
}
#endif // __APPLE__
#else
#error "Monotonic clock not implemented"
#endif
#endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK