[libc] add `pthread_rwlock_clockrdlock` and `pthread_rwlock_clockwrlock` GNU extensions

[SchrodingerZhu]

Function: int pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
Behaves like pthread_rwlock_timedrdlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

Function: int pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
Behaves like pthread_rwlock_timedwrlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

These should be easy to do since we already have all the abilities to handle realtime and monolithic clocks. See:

llvm-project/libc/src/pthread/pthread_rwlock_timedwrlock.cpp

Line 31 in 9b02b75

internal::AbsTimeout::from_timespec(*abstime, /*is_realtime=*/true);

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

> Function: int pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
> Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
> Behaves like pthread_rwlock_timedrdlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

> Function: int pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
> Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
> Behaves like pthread_rwlock_timedwrlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

These should be easy to do since we already have all the abilities to handle realtime and monolithic clocks. See:

llvm-project/libc/src/pthread/pthread_rwlock_timedwrlock.cpp

Line 31 in 9b02b75

internal::AbsTimeout::from_timespec(*abstime, /*is_realtime=*/true);

[llvmbot]

@llvm/issue-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

> Function: int pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
> Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
> Behaves like pthread_rwlock_timedrdlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

> Function: int pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t clockid, const struct timespec *abstime)
> Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.
> Behaves like pthread_rwlock_timedwrlock except the time abstime is measured against the clock specified by clockid rather than CLOCK_REALTIME. Currently, clockid must be either CLOCK_MONOTONIC or CLOCK_REALTIME, otherwise EINVAL is returned.

These should be easy to do since we already have all the abilities to handle realtime and monolithic clocks. See:

llvm-project/libc/src/pthread/pthread_rwlock_timedwrlock.cpp

Line 31 in 9b02b75

internal::AbsTimeout::from_timespec(*abstime, /*is_realtime=*/true);

[SchrodingerZhu]

It is also within POSIX.1-2024 now.

[Eric977]

Hi! I would like to give this a try.

[SchrodingerZhu]

Sure, go ahead!

[nickdesaulniers]

fixed in 44df89c