rust/library/std
Dylan DPC cbe5e7bc62
Rollup merge of #102773 - joboet:apple_parker, r=thomcc
Use semaphores for thread parking on Apple platforms

Currently we use a mutex-condvar pair for thread parking on Apple systems. Unfortunately, `pthread_cond_timedwait` uses the real-time clock for measuring time, which causes problems when the system time changes. The parking implementation in this PR uses a semaphore instead, which measures monotonic time by default, avoiding these issues. As a further benefit, this has the potential to improve performance a bit, since `unpark` does not need to wait for a lock to be released.

Since the Mach semaphores are poorly documented (I could not find availability or stability guarantees for instance), this uses a [dispatch semaphore](https://developer.apple.com/documentation/dispatch/dispatch_semaphore?language=objc) instead. While it adds a layer of indirection (it uses Mach semaphores internally), the overhead is probably negligible.

Tested on macOS 12.5.

r? ``````@thomcc``````
2022-10-15 15:45:30 +05:30
..
benches mv std libs to library/ 2020-07-27 19:51:13 -05:00
primitive_docs Add primitive documentation to libcore 2021-09-12 02:23:08 +00:00
src Rollup merge of #102773 - joboet:apple_parker, r=thomcc 2022-10-15 15:45:30 +05:30
tests Sort target features alphabetically 2022-10-14 22:01:18 +02:00
build.rs Library changes for Apple WatchOS 2022-07-20 08:57:36 +01:00
Cargo.toml Update stdarch 2022-09-15 13:05:28 -04:00