PR libstdc++/41861 Add full steady_clock support to condition_variable
The pthread_cond_clockwait function is available in glibc since the 2.30 release. If this function is available in the C library it can be used to fix PR libstdc++/41861 by supporting std::chrono::steady_clock properly with std::condition_variable. This means that code using std::condition_variable::wait_for or std::condition_variable::wait_until with std::chrono::steady_clock is no longer subject to timing out early or potentially waiting for much longer if the system clock is warped at an inopportune moment. If pthread_cond_clockwait is available then std::chrono::steady_clock is deemed to be the "best" clock available which means that it is used for the relative wait_for calls and absolute wait_until calls using user-defined clocks. Calls explicitly using std::chrono::system_clock continue to use CLOCK_REALTIME via __gthread_cond_timedwait. If pthread_cond_clockwait is not available then std::chrono::system_clock is deemed to be the "best" clock available which means that the previous suboptimal behaviour remains. 2019-09-04 Mike Crowe <mac@mcrowe.com> PR libstdc++/41861 * acinclude.m4 (GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT): Check for new pthread_cond_clockwait function. * configure.ac: Use GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT. * configure: Regenerate. * config.h.in: Regenerate. * include/std/condition_variable: (condition_variable): Rename __steady_clock_t typedef and add system_clock. Change __clock_t to be a typedef for the preferred clock to convert arbitrary other clocks to. [_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (wait_until): Add a steady_clock overload. (wait_until): Change __clock_t overload to use system_clock. [_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (__wait_until_impl): Add steady_clock overload that calls pthread_cond_clockwait. (__wait_until_impl): Change __clock_t overload to use system_clock. (condition_variable_any) [_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT]: Use steady_clock for __clock_t if pthread_cond_clockwait is available. From-SVN: r275390
This commit is contained in:
Mike Crowe
Jonathan Wakely
parent
76e0dd66c8
commit
ad4d1d21ad
6 changed files with 191 additions and 11 deletions
|
|
@ -1,3 +1,23 @@
|
|||
2019-09-04 Mike Crowe <mac@mcrowe.com>
|
||||
|
||||
PR libstdc++/41861
|
||||
* acinclude.m4 (GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT): Check for new
|
||||
pthread_cond_clockwait function.
|
||||
* configure.ac: Use GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT.
|
||||
* configure: Regenerate.
|
||||
* config.h.in: Regenerate.
|
||||
* include/std/condition_variable: (condition_variable): Rename
|
||||
__steady_clock_t typedef and add system_clock. Change __clock_t to be
|
||||
a typedef for the preferred clock to convert arbitrary other clocks to.
|
||||
[_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (wait_until): Add a steady_clock
|
||||
overload.
|
||||
(wait_until): Change __clock_t overload to use system_clock.
|
||||
[_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (__wait_until_impl): Add
|
||||
steady_clock overload that calls pthread_cond_clockwait.
|
||||
(__wait_until_impl): Change __clock_t overload to use system_clock.
|
||||
(condition_variable_any) [_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT]: Use
|
||||
steady_clock for __clock_t if pthread_cond_clockwait is available.
|
||||
|
||||
2019-09-04 Mike Crowe <mac@mcrowe.com>
|
||||
|
||||
* testsuite/30_threads/condition_variable/members/2.cc (test01):
|
||||
|
|
|
|||
|
|
@ -4193,6 +4193,37 @@ AC_DEFUN([GLIBCXX_CHECK_PTHREADS_NUM_PROCESSORS_NP], [
|
|||
AC_LANG_RESTORE
|
||||
])
|
||||
|
||||
dnl
|
||||
dnl Check whether pthread_cond_clockwait is available in <pthread.h> for std::condition_variable to use,
|
||||
dnl and define _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT.
|
||||
dnl
|
||||
AC_DEFUN([GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT], [
|
||||
|
||||
AC_LANG_SAVE
|
||||
AC_LANG_CPLUSPLUS
|
||||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||||
CXXFLAGS="$CXXFLAGS -fno-exceptions"
|
||||
ac_save_LIBS="$LIBS"
|
||||
LIBS="$LIBS -lpthread"
|
||||
|
||||
AC_MSG_CHECKING([for pthread_cond_clockwait])
|
||||
AC_CACHE_VAL(glibcxx_cv_PTHREAD_COND_CLOCKWAIT, [
|
||||
GCC_TRY_COMPILE_OR_LINK(
|
||||
[#include <pthread.h>],
|
||||
[pthread_mutex_t mutex; pthread_cond_t cond; struct timespec ts; int n = pthread_cond_clockwait(&cond, &mutex, 0, &ts);],
|
||||
[glibcxx_cv_PTHREAD_COND_CLOCKWAIT=yes],
|
||||
[glibcxx_cv_PTHREAD_COND_CLOCKWAIT=no])
|
||||
])
|
||||
if test $glibcxx_cv_PTHREAD_COND_CLOCKWAIT = yes; then
|
||||
AC_DEFINE(_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT, 1, [Define if pthread_cond_clockwait is available in <pthread.h>.])
|
||||
fi
|
||||
AC_MSG_RESULT($glibcxx_cv_PTHREAD_COND_CLOCKWAIT)
|
||||
|
||||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||||
LIBS="$ac_save_LIBS"
|
||||
AC_LANG_RESTORE
|
||||
])
|
||||
|
||||
dnl
|
||||
dnl Check whether sysctl is available in <pthread.h>, and define _GLIBCXX_USE_SYSCTL_HW_NCPU.
|
||||
dnl
|
||||
|
|
|
|||
|
|
@ -991,6 +991,9 @@
|
|||
/* Define if pthreads_num_processors_np is available in <pthread.h>. */
|
||||
#undef _GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP
|
||||
|
||||
/* Define if pthread_cond_clockwait is available in <pthread.h>. */
|
||||
#undef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
|
||||
|
||||
/* Define if POSIX read/write locks are available in <gthr.h>. */
|
||||
#undef _GLIBCXX_USE_PTHREAD_RWLOCK_T
|
||||
|
||||
|
|
|
|||
83
libstdc++-v3/configure
vendored
83
libstdc++-v3/configure
vendored
|
|
@ -21581,6 +21581,89 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
|
|||
|
||||
|
||||
|
||||
# For pthread_cond_clockwait
|
||||
|
||||
|
||||
|
||||
ac_ext=cpp
|
||||
ac_cpp='$CXXCPP $CPPFLAGS'
|
||||
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
|
||||
ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
|
||||
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
|
||||
|
||||
ac_save_CXXFLAGS="$CXXFLAGS"
|
||||
CXXFLAGS="$CXXFLAGS -fno-exceptions"
|
||||
ac_save_LIBS="$LIBS"
|
||||
LIBS="$LIBS -lpthread"
|
||||
|
||||
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_cond_clockwait" >&5
|
||||
$as_echo_n "checking for pthread_cond_clockwait... " >&6; }
|
||||
if ${glibcxx_cv_PTHREAD_COND_CLOCKWAIT+:} false; then :
|
||||
$as_echo_n "(cached) " >&6
|
||||
else
|
||||
|
||||
if test x$gcc_no_link = xyes; then
|
||||
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
|
||||
/* end confdefs.h. */
|
||||
#include <pthread.h>
|
||||
int
|
||||
main ()
|
||||
{
|
||||
pthread_mutex_t mutex; pthread_cond_t cond; struct timespec ts; int n = pthread_cond_clockwait(&cond, &mutex, 0, &ts);
|
||||
;
|
||||
return 0;
|
||||
}
|
||||
_ACEOF
|
||||
if ac_fn_cxx_try_compile "$LINENO"; then :
|
||||
glibcxx_cv_PTHREAD_COND_CLOCKWAIT=yes
|
||||
else
|
||||
glibcxx_cv_PTHREAD_COND_CLOCKWAIT=no
|
||||
fi
|
||||
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
|
||||
else
|
||||
if test x$gcc_no_link = xyes; then
|
||||
as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
|
||||
fi
|
||||
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
|
||||
/* end confdefs.h. */
|
||||
#include <pthread.h>
|
||||
int
|
||||
main ()
|
||||
{
|
||||
pthread_mutex_t mutex; pthread_cond_t cond; struct timespec ts; int n = pthread_cond_clockwait(&cond, &mutex, 0, &ts);
|
||||
;
|
||||
return 0;
|
||||
}
|
||||
_ACEOF
|
||||
if ac_fn_cxx_try_link "$LINENO"; then :
|
||||
glibcxx_cv_PTHREAD_COND_CLOCKWAIT=yes
|
||||
else
|
||||
glibcxx_cv_PTHREAD_COND_CLOCKWAIT=no
|
||||
fi
|
||||
rm -f core conftest.err conftest.$ac_objext \
|
||||
conftest$ac_exeext conftest.$ac_ext
|
||||
fi
|
||||
|
||||
fi
|
||||
|
||||
if test $glibcxx_cv_PTHREAD_COND_CLOCKWAIT = yes; then
|
||||
|
||||
$as_echo "#define _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 1" >>confdefs.h
|
||||
|
||||
fi
|
||||
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_PTHREAD_COND_CLOCKWAIT" >&5
|
||||
$as_echo "$glibcxx_cv_PTHREAD_COND_CLOCKWAIT" >&6; }
|
||||
|
||||
CXXFLAGS="$ac_save_CXXFLAGS"
|
||||
LIBS="$ac_save_LIBS"
|
||||
ac_ext=c
|
||||
ac_cpp='$CPP $CPPFLAGS'
|
||||
ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
|
||||
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
|
||||
ac_compiler_gnu=$ac_cv_c_compiler_gnu
|
||||
|
||||
|
||||
|
||||
|
||||
ac_fn_c_check_header_mongrel "$LINENO" "locale.h" "ac_cv_header_locale_h" "$ac_includes_default"
|
||||
if test "x$ac_cv_header_locale_h" = xyes; then :
|
||||
|
|
|
|||
|
|
@ -220,6 +220,9 @@ GLIBCXX_ENABLE_LIBSTDCXX_TIME
|
|||
# Check for tmpnam which is obsolescent in POSIX.1-2008
|
||||
GLIBCXX_CHECK_TMPNAM
|
||||
|
||||
# For pthread_cond_clockwait
|
||||
GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT
|
||||
|
||||
AC_LC_MESSAGES
|
||||
|
||||
# For hardware_concurrency
|
||||
|
|
|
|||
|
|
@ -65,8 +65,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
/// condition_variable
|
||||
class condition_variable
|
||||
{
|
||||
typedef chrono::system_clock __clock_t;
|
||||
typedef chrono::steady_clock __steady_clock_t;
|
||||
using steady_clock = chrono::steady_clock;
|
||||
using system_clock = chrono::system_clock;
|
||||
#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
|
||||
using __clock_t = steady_clock;
|
||||
#else
|
||||
using __clock_t = system_clock;
|
||||
#endif
|
||||
typedef __gthread_cond_t __native_type;
|
||||
|
||||
#ifdef __GTHREAD_COND_INIT
|
||||
|
|
@ -101,10 +106,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
wait(__lock);
|
||||
}
|
||||
|
||||
#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
|
||||
template<typename _Duration>
|
||||
cv_status
|
||||
wait_until(unique_lock<mutex>& __lock,
|
||||
const chrono::time_point<__clock_t, _Duration>& __atime)
|
||||
const chrono::time_point<steady_clock, _Duration>& __atime)
|
||||
{ return __wait_until_impl(__lock, __atime); }
|
||||
#endif
|
||||
|
||||
template<typename _Duration>
|
||||
cv_status
|
||||
wait_until(unique_lock<mutex>& __lock,
|
||||
const chrono::time_point<system_clock, _Duration>& __atime)
|
||||
{ return __wait_until_impl(__lock, __atime); }
|
||||
|
||||
template<typename _Clock, typename _Duration>
|
||||
|
|
@ -112,7 +125,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
wait_until(unique_lock<mutex>& __lock,
|
||||
const chrono::time_point<_Clock, _Duration>& __atime)
|
||||
{
|
||||
// DR 887 - Sync unknown clock to known clock.
|
||||
const typename _Clock::time_point __c_entry = _Clock::now();
|
||||
const __clock_t::time_point __s_entry = __clock_t::now();
|
||||
const auto __delta = __atime - __c_entry;
|
||||
|
|
@ -145,11 +157,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
wait_for(unique_lock<mutex>& __lock,
|
||||
const chrono::duration<_Rep, _Period>& __rtime)
|
||||
{
|
||||
using __dur = typename __steady_clock_t::duration;
|
||||
using __dur = typename steady_clock::duration;
|
||||
auto __reltime = chrono::duration_cast<__dur>(__rtime);
|
||||
if (__reltime < __rtime)
|
||||
++__reltime;
|
||||
return wait_until(__lock, __steady_clock_t::now() + __reltime);
|
||||
return wait_until(__lock, steady_clock::now() + __reltime);
|
||||
}
|
||||
|
||||
template<typename _Rep, typename _Period, typename _Predicate>
|
||||
|
|
@ -158,11 +170,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
const chrono::duration<_Rep, _Period>& __rtime,
|
||||
_Predicate __p)
|
||||
{
|
||||
using __dur = typename __steady_clock_t::duration;
|
||||
using __dur = typename steady_clock::duration;
|
||||
auto __reltime = chrono::duration_cast<__dur>(__rtime);
|
||||
if (__reltime < __rtime)
|
||||
++__reltime;
|
||||
return wait_until(__lock, __steady_clock_t::now() + __reltime,
|
||||
return wait_until(__lock, steady_clock::now() + __reltime,
|
||||
std::move(__p));
|
||||
}
|
||||
|
||||
|
|
@ -171,10 +183,34 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
{ return &_M_cond; }
|
||||
|
||||
private:
|
||||
#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
|
||||
template<typename _Dur>
|
||||
cv_status
|
||||
__wait_until_impl(unique_lock<mutex>& __lock,
|
||||
const chrono::time_point<__clock_t, _Dur>& __atime)
|
||||
const chrono::time_point<steady_clock, _Dur>& __atime)
|
||||
{
|
||||
auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
|
||||
auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
|
||||
|
||||
__gthread_time_t __ts =
|
||||
{
|
||||
static_cast<std::time_t>(__s.time_since_epoch().count()),
|
||||
static_cast<long>(__ns.count())
|
||||
};
|
||||
|
||||
pthread_cond_clockwait(&_M_cond, __lock.mutex()->native_handle(),
|
||||
CLOCK_MONOTONIC,
|
||||
&__ts);
|
||||
|
||||
return (steady_clock::now() < __atime
|
||||
? cv_status::no_timeout : cv_status::timeout);
|
||||
}
|
||||
#endif
|
||||
|
||||
template<typename _Dur>
|
||||
cv_status
|
||||
__wait_until_impl(unique_lock<mutex>& __lock,
|
||||
const chrono::time_point<system_clock, _Dur>& __atime)
|
||||
{
|
||||
auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
|
||||
auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
|
||||
|
|
@ -188,7 +224,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
__gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
|
||||
&__ts);
|
||||
|
||||
return (__clock_t::now() < __atime
|
||||
return (system_clock::now() < __atime
|
||||
? cv_status::no_timeout : cv_status::timeout);
|
||||
}
|
||||
};
|
||||
|
|
@ -208,7 +244,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|||
// Like above, but mutex is not required to have try_lock.
|
||||
class condition_variable_any
|
||||
{
|
||||
typedef chrono::system_clock __clock_t;
|
||||
#ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
|
||||
using __clock_t = chrono::steady_clock;
|
||||
#else
|
||||
using __clock_t = chrono::system_clock;
|
||||
#endif
|
||||
condition_variable _M_cond;
|
||||
shared_ptr<mutex> _M_mutex;
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue