This is the equivalent to PR libstdc++/91906, but for shared_mutex.
A non-standard clock may tick more slowly than std::chrono::steady_clock.
This means that we risk returning false early when the specified timeout
may not have expired. This can be avoided by looping until the timeout time
as reported by the non-standard clock has been reached.
Unfortunately, we have no way to tell whether the non-standard clock ticks
more quickly that std::chrono::steady_clock. If it does then we risk
returning later than would be expected, but that is unavoidable without
waking up periodically to check, which would be rather too expensive.
François Dumont pointed out[1] a flaw in an earlier version of this patch
that revealed a hole in the test coverage, so I've added a new test that
try_lock_until acts as try_lock if the timeout has already expired.
[1] https://gcc.gnu.org/ml/libstdc++/2019-10/msg00021.html
2019-12-02 Mike Crowe <mac@mcrowe.com>
Fix try_lock_until and try_lock_shared_until on arbitrary clock
* include/std/shared_mutex (shared_timed_mutex::try_lock_until)
(shared_timed_mutex::try_lock_shared_until): Loop until the absolute
timeout time is reached as measured against the appropriate clock.
* testsuite/30_threads/shared_timed_mutex/try_lock_until/1.cc: New
file. Test try_lock_until and try_lock_shared_until timeouts against
various clocks.
* testsuite/30_threads/shared_timed_mutex/try_lock_until/1.cc: New
file. Test try_lock_until and try_lock_shared_until timeouts against
various clocks.
From-SVN: r278904
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
Define the thread-safe pool resource, using a shared_mutex to allow
multiple threads to concurrently allocate from thread-specific pools.
Define new weak symbols for the pthread_rwlock_t functions, to avoid
making libstdc++.so depend on libpthread.so
When the necessary Gthread support is absent only define the
feature-test macro to 1, rather than 201603. This is intended to imply
incomplete support, because everything except synchronized_pool_resource
works.
Implement std::pmr::synchronized_pool_resource
* config/abi/pre/gnu.ver: Add new symbols.
* include/std/memory_resource [_GLIBCXX_HAS_GTHREADS]
(__cpp_lib_memory_resource): Define to expected value, 201603.
(synchronized_pool_resource): New class.
[!_GLIBCXX_HAS_GTHREADS] (__cpp_lib_memory_resource): Define to 1.
* include/std/shared_mutex (__glibcxx_rwlock_rdlock)
(__glibcxx_rwlock_tryrdlock, __glibcxx_rwlock_wrlock)
(__glibcxx_rwlock_trywrlock, __glibcxx_rwlock_unlock)
(__glibcxx_rwlock_destroy, __glibcxx_rwlock_init)
(__glibcxx_rwlock_timedrdlock, __glibcxx_rwlock_timedwrlock): Define
weak symbols for POSIX rwlock functions.
(__shared_mutex_pthread): Use weak symbols.
* include/std/version (__cpp_lib_memory_resource): Define.
* src/c++17/memory_resource.cc [_GLIBCXX_HAS_GTHREADS]
(synchronized_pool_resource::_TPools): New class.
(destroy_TPools): New function for pthread_key_create destructor.
(synchronized_pool_resource::synchronized_pool_resource)
(synchronized_pool_resource::~synchronized_pool_resource)
(synchronized_pool_resource::release)
(synchronized_pool_resource::do_allocate)
(synchronized_pool_resource::do_deallocate): Define public members.
(synchronized_pool_resource::_M_thread_specific_pools)
(synchronized_pool_resource::_M_alloc_tpools)
(synchronized_pool_resource::_M_alloc_shared_tpools): Define private
members.
* testsuite/20_util/synchronized_pool_resource/allocate.cc: New test.
* testsuite/20_util/synchronized_pool_resource/cons.cc: New test.
* testsuite/20_util/synchronized_pool_resource/is_equal.cc: New test.
* testsuite/20_util/synchronized_pool_resource/multithreaded.cc: New
test.
* testsuite/20_util/synchronized_pool_resource/release.cc: New test.
* testsuite/performance/20_util/memory_resource/pools.cc: Add
multithreaded tests using pmr::synchronized_pool_resource.
From-SVN: r266242
PR libstdc++/79433
* doc/xml/manual/status_cxx2017.xml: Update feature-test macros.
* doc/html/*: Regenerate.
* include/Makefile.am: Remove <bits/c++17_warning.h>.
* include/Makefile.in: Regenerate.
* include/bits/c++17_warning.h: Remove.
* include/bits/string_view.tcc: Do not include <bits/c++17_warning.h>
for pre-C++17 modes.
* include/std/any: Likewise.
(__cpp_lib_any): Define.
* include/std/mutex (__cpp_lib_scoped_lock): Adjust value as per new
SD-6 draft.
* include/std/numeric (__cpp_lib_gcd_lcm): Define as per new SD-6
draft.
* include/std/optional: Do not include <bits/c++17_warning.h>.
(__cpp_lib_optional): Define.
* include/std/shared_mutex: Do not include <bits/c++14_warning.h>.
* include/std/string_view: Do not include <bits/c++17_warning.h>.
(__cpp_lib_string_view): Define.
* include/std/variant: Do not include <bits/c++17_warning.h>.
(__cpp_lib_variant): Define.
* testsuite/20_util/optional/cons/value_neg.cc: Adjust dg-error line
numbers.
* testsuite/26_numerics/gcd/1.cc: Test for __cpp_lib_gcd_lcm.
* testsuite/26_numerics/gcd/gcd_neg.cc: Adjust dg-error line
numbers.
* testsuite/26_numerics/lcm/1.cc: Test for __cpp_lib_gcd_lcm.
* testsuite/26_numerics/lcm/lcm_neg.cc: Adjust dg-error line
numbers.
* testsuite/30_threads/scoped_lock/requirements/typedefs.cc: Adjust
expected value of __cpp_lib_scoped_lock.
From-SVN: r252018
* include/std/shared_mutex (__shared_mutex_pthread,
__shared_mutex_cv): New helper types implementing the shared mutex
requirements.
(shared_mutex): New type for C++17.
(shared_timed_mutex): Derive from one of the new helper types.
* testsuite/30_threads/shared_mutex/cons/1.cc: New.
* testsuite/30_threads/shared_mutex/cons/assign_neg.cc: New.
* testsuite/30_threads/shared_mutex/cons/copy_neg.cc: New.
* testsuite/30_threads/shared_mutex/requirements/standard_layout.cc:
New.
* testsuite/30_threads/shared_mutex/try_lock/1.cc: New.
* testsuite/30_threads/shared_mutex/try_lock/2.cc: New.
From-SVN: r224158
* include/std/shared_mutex (shared_timed_mutex): Add comments to
explain the logic in the non-pthread_rwlock_t version.
(_Mutex): Remove redundant type.
(_M_n_readers): Rename to _S_max_readers.
(_M_write_entered, _M_readers): New convenience functions.
(lock, lock_shared, try_lock_shared, unlock_shared): Use convenience
functions. Use predicates with condition variables. Simplify bitwise
operations.
(try_lock_for, try_shared_lock_for): Convert duration to time_point
and call try_lock_until or try_shared_lock_until respectively.
(try_lock_until, try_shared_lock_until): Wait on the condition
variables until the specified time passes.
(unlock): Add Debug Mode assertion.
(unlock_shared): Add Debug Mode assertion.
* testsuite/30_threads/shared_timed_mutex/try_lock/3.cc: New.
From-SVN: r221970
PR libstdc++/57641
* include/std/mutex (timed_mutex, recursive_timed_mutex): Move common
functionality to new __timed_mutex_impl mixin. Overload try_lock_until
to handle conversion between different clocks. Replace constrained
__try_lock_for_impl overloads with conditional increment.
* include/std/shared_mutex (shared_mutex::_Mutex): Use the new mixin.
* testsuite/30_threads/timed_mutex/try_lock_until/57641.cc: New.
From-SVN: r200180
