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acinclude.m4 (GLIBCXX_CHECK_GTHREADS): Check for pthread_rwlock_t.

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2015-03-18  Jonathan Wakely  <jwakely@redhat.com>
	    Torvald Riegel  <triegel@redhat.com>

	* acinclude.m4 (GLIBCXX_CHECK_GTHREADS): Check for pthread_rwlock_t.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* include/std/shared_mutex: Check _GLIBCXX_USE_PTHREAD_RWLOCK_T.
	(shared_timed_mutex::_M_rwlock): Use PTHREAD_RWLOCK_INITIALIZER.
	(shared_timed_mutex::lock_shared()): Retry on EAGAIN.
	(shared_timed_mutex::try_lock_shared_until()): Retry on EAGAIN and
	EDEADLK.

Co-Authored-By: Torvald Riegel <triegel@redhat.com>

From-SVN: r221484
This commit is contained in:
Jonathan Wakely 2015-03-18 10:53:38 +00:00 • committed by Jonathan Wakely
parent 41cee85a34
commit 5e0216f173
5 changed files with 134 additions and 23 deletions
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12
libstdc++-v3/ChangeLog
View file

@ -1,3 +1,15 @@
2015-03-18 Jonathan Wakely <jwakely@redhat.com>
Torvald Riegel <triegel@redhat.com>
* acinclude.m4 (GLIBCXX_CHECK_GTHREADS): Check for pthread_rwlock_t.
* config.h.in: Regenerate.
* configure: Regenerate.
* include/std/shared_mutex: Check _GLIBCXX_USE_PTHREAD_RWLOCK_T.
(shared_timed_mutex::_M_rwlock): Use PTHREAD_RWLOCK_INITIALIZER.
(shared_timed_mutex::lock_shared()): Retry on EAGAIN.
(shared_timed_mutex::try_lock_shared_until()): Retry on EAGAIN and
EDEADLK.
2015-03-17 Jonathan Wakely <jwakely@redhat.com>
* libsupc++/nested_exception.h: Do not try to derive from final

7
libstdc++-v3/acinclude.m4
View file

@ -3563,6 +3563,13 @@ AC_DEFUN([GLIBCXX_CHECK_GTHREADS], [
if test x"$ac_has_gthreads" = x"yes"; then
AC_DEFINE(_GLIBCXX_HAS_GTHREADS, 1,
[Define if gthreads library is available.])
# Also check for pthread_rwlock_t for std::shared_timed_mutex in C++14
AC_CHECK_TYPE([pthread_rwlock_t],
[AC_DEFINE([_GLIBCXX_USE_PTHREAD_RWLOCK_T], 1,
[Define if POSIX read/write locks are available in <gthr.h>.])],
[],
[#include "gthr.h"])
fi
CXXFLAGS="$ac_save_CXXFLAGS"

3
libstdc++-v3/config.h.in
View file

@ -851,6 +851,9 @@
/* Define if pthreads_num_processors_np is available in <pthread.h>. */
#undef _GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP
/* Define if POSIX read/write locks are available in <gthr.h>. */
#undef _GLIBCXX_USE_PTHREAD_RWLOCK_T
/* Define if /dev/random and /dev/urandom are available for the random_device
of TR1 (Chapter 5.1). */
#undef _GLIBCXX_USE_RANDOM_TR1

84
libstdc++-v3/configure vendored
View file

@ -2498,6 +2498,60 @@ $as_echo "$ac_res" >&6; }
eval $as_lineno_stack; test "x$as_lineno_stack" = x && { as_lineno=; unset as_lineno;}
} # ac_fn_c_check_type
# ac_fn_cxx_check_type LINENO TYPE VAR INCLUDES
# ---------------------------------------------
# Tests whether TYPE exists after having included INCLUDES, setting cache
# variable VAR accordingly.
ac_fn_cxx_check_type ()
{
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
$as_echo_n "checking for $2... " >&6; }
if { as_var=$3; eval "test \"\${$as_var+set}\" = set"; }; then :
$as_echo_n "(cached) " >&6
else
eval "$3=no"
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof ($2))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof (($2)))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
else
eval "$3=yes"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
eval ac_res=\$$3
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
$as_echo "$ac_res" >&6; }
eval $as_lineno_stack; test "x$as_lineno_stack" = x && { as_lineno=; unset as_lineno;}
} # ac_fn_cxx_check_type
cat >config.log <<_ACEOF
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.
@ -11539,7 +11593,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 11542 "configure"
#line 11596 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@ -11645,7 +11699,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 11648 "configure"
#line 11702 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@ -15065,7 +15119,7 @@ fi
#
# Fake what AC_TRY_COMPILE does. XXX Look at redoing this new-style.
cat > conftest.$ac_ext << EOF
#line 15068 "configure"
#line 15122 "configure"
struct S { ~S(); };
void bar();
void foo()
@ -15417,7 +15471,7 @@ $as_echo "$glibcxx_cv_atomic_long_long" >&6; }
# Fake what AC_TRY_COMPILE does.
cat > conftest.$ac_ext << EOF
#line 15420 "configure"
#line 15474 "configure"
int main()
{
typedef bool atomic_type;
@ -15452,7 +15506,7 @@ $as_echo "$glibcxx_cv_atomic_bool" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 15455 "configure"
#line 15509 "configure"
int main()
{
typedef short atomic_type;
@ -15487,7 +15541,7 @@ $as_echo "$glibcxx_cv_atomic_short" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 15490 "configure"
#line 15544 "configure"
int main()
{
// NB: _Atomic_word not necessarily int.
@ -15523,7 +15577,7 @@ $as_echo "$glibcxx_cv_atomic_int" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 15526 "configure"
#line 15580 "configure"
int main()
{
typedef long long atomic_type;
@ -15602,7 +15656,7 @@ $as_echo "$as_me: WARNING: Performance of certain classes will degrade as a resu
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
#line 15605 "configure"
#line 15659 "configure"
int main()
{
_Decimal32 d1;
@ -15644,7 +15698,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
#line 15647 "configure"
#line 15701 "configure"
template<typename T1, typename T2>
struct same
{ typedef T2 type; };
@ -15678,7 +15732,7 @@ $as_echo "$enable_int128" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 15681 "configure"
#line 15735 "configure"
template<typename T1, typename T2>
struct same
{ typedef T2 type; };
@ -78786,6 +78840,16 @@ $as_echo "$ac_has_gthreads" >&6; }
$as_echo "#define _GLIBCXX_HAS_GTHREADS 1" >>confdefs.h
# Also check for pthread_rwlock_t for std::shared_timed_mutex in C++14
ac_fn_cxx_check_type "$LINENO" "pthread_rwlock_t" "ac_cv_type_pthread_rwlock_t" "#include \"gthr.h\"
"
if test "x$ac_cv_type_pthread_rwlock_t" = x""yes; then :
$as_echo "#define _GLIBCXX_USE_PTHREAD_RWLOCK_T 1" >>confdefs.h
fi
fi
CXXFLAGS="$ac_save_CXXFLAGS"

51
libstdc++-v3/include/std/shared_mutex
View file

@ -57,10 +57,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// shared_timed_mutex
class shared_timed_mutex
{
#if defined(__GTHREADS_CXX0X)
#ifdef _GLIBCXX_USE_PTHREAD_RWLOCK_T
typedef chrono::system_clock __clock_t;
pthread_rwlock_t _M_rwlock;
#ifdef PTHREAD_RWLOCK_INITIALIZER
pthread_rwlock_t _M_rwlock = PTHREAD_RWLOCK_INITIALIZER;
public:
shared_timed_mutex() = default;
~shared_timed_mutex() = default;
#else
pthread_rwlock_t _M_rwlock;
public:
shared_timed_mutex()
@ -82,6 +89,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Errors not handled: EBUSY, EINVAL
_GLIBCXX_DEBUG_ASSERT(__ret == 0);
}
#endif
shared_timed_mutex(const shared_timed_mutex&) = delete;
shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;
@ -165,12 +173,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void
lock_shared()
{
int __ret = pthread_rwlock_rdlock(&_M_rwlock);
int __ret;
// We retry if we exceeded the maximum number of read locks supported by
// the POSIX implementation; this can result in busy-waiting, but this
// is okay based on the current specification of forward progress
// guarantees by the standard.
do
__ret = pthread_rwlock_rdlock(&_M_rwlock);
while (__ret == EAGAIN);
if (__ret == EDEADLK)
__throw_system_error(int(errc::resource_deadlock_would_occur));
if (__ret == EAGAIN)
// Maximum number of read locks has been exceeded.
__throw_system_error(int(errc::device_or_resource_busy));
// Errors not handled: EINVAL
_GLIBCXX_DEBUG_ASSERT(__ret == 0);
}
@ -210,11 +222,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static_cast<long>(__ns.count())
};
int __ret = pthread_rwlock_timedrdlock(&_M_rwlock, &__ts);
// If the maximum number of read locks has been exceeded, or we would
// deadlock, we just fail to acquire the lock. Unlike for lock(),
// we are not allowed to throw an exception.
if (__ret == ETIMEDOUT || __ret == EAGAIN || __ret == EDEADLK)
int __ret;
// Unlike for lock(), we are not allowed to throw an exception so if
// the maximum number of read locks has been exceeded, or we would
// deadlock, we just try to acquire the lock again (and will time out
// eventually).
// In cases where we would exceed the maximum number of read locks
// throughout the whole time until the timeout, we will fail to
// acquire the lock even if it would be logically free; however, this
// is allowed by the standard, and we made a "strong effort"
// (see C++14 30.4.1.4p26).
// For cases where the implementation detects a deadlock we
// intentionally block and timeout so that an early return isn't
// mistaken for a spurious failure, which might help users realise
// there is a deadlock.
do
__ret = pthread_rwlock_timedrdlock(&_M_rwlock, &__ts);
while (__ret == EAGAIN || __ret == EDEADLK);
if (__ret == ETIMEDOUT)
return false;
// Errors not handled: EINVAL
_GLIBCXX_DEBUG_ASSERT(__ret == 0);
@ -241,7 +266,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
unlock();
}
#else // defined(__GTHREADS_CXX0X)
#else // ! _GLIBCXX_USE_PTHREAD_RWLOCK_T
#if _GTHREAD_USE_MUTEX_TIMEDLOCK
struct _Mutex : mutex, __timed_mutex_impl<_Mutex>
@ -438,7 +463,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_gate1.notify_one();
}
}
#endif // !defined(__GTHREADS_CXX0X)
#endif // ! _GLIBCXX_USE_PTHREAD_RWLOCK_T
};
#endif // _GLIBCXX_HAS_GTHREADS