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author | Mike Crowe <mac@mcrowe.com> | 2019-12-02 16:23:10 +0000 |
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committer | Jonathan Wakely <redi@gcc.gnu.org> | 2019-12-02 16:23:10 +0000 |
commit | ab40695a46c6649bac40f4251e37993d73fa7a13 (patch) | |
tree | 1bdab64d9d7ca9afe4f3b1d7c4affbcb4be178f3 /libstdc++-v3/configure | |
parent | a7334019b11798a9e791edef62a690b521e78a5b (diff) | |
download | gcc-ab40695a46c6649bac40f4251e37993d73fa7a13.zip gcc-ab40695a46c6649bac40f4251e37993d73fa7a13.tar.gz gcc-ab40695a46c6649bac40f4251e37993d73fa7a13.tar.bz2 |
libstdc++: Add full steady_clock support to shared_timed_mutex
The pthread_rwlock_clockrdlock and pthread_rwlock_clockwrlock functions
were added to glibc in v2.30. They have also been added to Android
Bionic. If these functions are available in the C library then they can
be used to implement shared_timed_mutex::try_lock_until,
shared_timed_mutex::try_lock_for,
shared_timed_mutex::try_lock_shared_until and
shared_timed_mutex::try_lock_shared_for so that they are no longer
unaffected by the system clock being warped. (This is the shared_mutex
equivalent of PR libstdc++/78237 for mutex.)
If the new functions are available then steady_clock is deemed to be the
"best" clock available which means that it is used for the relative
try_lock_for calls and absolute try_lock_until calls using steady_clock
and user-defined clocks. It's not possible to have
_GLIBCXX_USE_PTHREAD_RWLOCK_CLOCKLOCK defined without
_GLIBCXX_USE_PTHREAD_RWLOCK_T, so the requirement that the clock be the
same as condition_variable is maintained. Calls explicitly using
system_clock (aka high_resolution_clock) continue to use CLOCK_REALTIME
via the old pthread_rwlock_timedrdlock and pthread_rwlock_timedwrlock
functions.
If the new functions are not available then system_clock is deemed to be
the "best" clock available which means that the previous suboptimal
behaviour remains.
Additionally, the user-defined clock used with
shared_timed_mutex::try_lock_for and shared_mutex::try_lock_shared_for
may have higher precision than __clock_t. We may need to round the
duration up to ensure that the timeout is long enough. (See
__timed_mutex_impl::_M_try_lock_for)
2019-12-02 Mike Crowe <mac@mcrowe.com>
Add full steady_clock support to shared_timed_mutex
* acinclude.m4 (GLIBCXX_CHECK_PTHREAD_RWLOCK_CLOCKLOCK): Define
to check for the presence of both pthread_rwlock_clockrdlock and
pthread_rwlock_clockwrlock.
* config.h.in: Regenerate.
* configure.ac: Call GLIBCXX_USE_PTHREAD_RWLOCK_CLOCKLOCK.
* configure: Regenerate.
* include/std/shared_mutex (shared_timed_mutex): Define __clock_t as
the best clock to use for relative waits.
(shared_timed_mutex::try_lock_for) Round up wait duration if necessary.
(shared_timed_mutex::try_lock_shared_for): Likewise.
(shared_timed_mutex::try_lock_until): Use existing try_lock_until
implementation for system_clock (which matches __clock_t when
_GLIBCCXX_USE_PTHREAD_RWLOCK_CLOCKLOCK is not defined). Add new
overload for steady_clock that uses pthread_rwlock_clockwrlock if it
is available. Simplify overload for non-standard clock to just call
try_lock_for with a relative timeout.
(shared_timed_mutex::try_lock_shared_until): Likewise.
From-SVN: r278903
Diffstat (limited to 'libstdc++-v3/configure')
-rwxr-xr-x | libstdc++-v3/configure | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure index a439bb8..b724215 100755 --- a/libstdc++-v3/configure +++ b/libstdc++-v3/configure @@ -21963,6 +21963,93 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu +# For pthread_rwlock_clockrdlock and pthread_rwlock_clockwrlock + + + + ac_ext=cpp +ac_cpp='$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_rwlock_clockrdlock, pthread_wlock_clockwrlock" >&5 +$as_echo_n "checking for pthread_rwlock_clockrdlock, pthread_wlock_clockwrlock... " >&6; } + if ${glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK+:} false; then : + $as_echo_n "(cached) " >&6 +else + + if test x$gcc_no_link = xyes; then + cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +#include <pthread.h> +int +main () +{ +pthread_rwlock_t rwl; struct timespec ts; + int n = pthread_rwlock_clockrdlock(&rwl, CLOCK_REALTIME, &ts); + int m = pthread_rwlock_clockwrlock(&rwl, CLOCK_REALTIME, &ts); + ; + return 0; +} +_ACEOF +if ac_fn_cxx_try_compile "$LINENO"; then : + glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK=yes +else + glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK=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.$ac_ext +/* end confdefs.h. */ +#include <pthread.h> +int +main () +{ +pthread_rwlock_t rwl; struct timespec ts; + int n = pthread_rwlock_clockrdlock(&rwl, CLOCK_REALTIME, &ts); + int m = pthread_rwlock_clockwrlock(&rwl, CLOCK_REALTIME, &ts); + ; + return 0; +} +_ACEOF +if ac_fn_cxx_try_link "$LINENO"; then : + glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK=yes +else + glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext +fi + +fi + + if test $glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK = yes; then + +$as_echo "#define _GLIBCXX_USE_PTHREAD_RWLOCK_CLOCKLOCK 1" >>confdefs.h + + fi + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK" >&5 +$as_echo "$glibcxx_cv_PTHREAD_RWLOCK_CLOCKLOCK" >&6; } + + CXXFLAGS="$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 : |