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Auto merge of #100579 - joboet:sync_mutex_everywhere, r=thomcc

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std: use `sync::Mutex` for internal statics

Since `sync::Mutex` is now `const`-constructible, it can be used for internal statics, removing the need for `sys_common::StaticMutex`. This adds some extra allocations on platforms which need to box their mutexes (currently SGX and some UNIX), but these will become unnecessary with the lock improvements tracked in #93740.

I changed the program argument implementation on Hermit, it does not need `Mutex` but can use atomics like some UNIX systems (ping `@mkroening` `@stlankes).`
This commit is contained in:
bors 2022-10-15 22:49:30 +00:00
commit ddc7fd9837
7 changed files with 47 additions and 123 deletions
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27
library/std/src/thread/mod.rs
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@ -1128,24 +1128,21 @@ impl ThreadId {
}
}
} else {
use crate::sys_common::mutex::StaticMutex;
use crate::sync::{Mutex, PoisonError};
// It is UB to attempt to acquire this mutex reentrantly!
static GUARD: StaticMutex = StaticMutex::new();
static mut COUNTER: u64 = 0;
static COUNTER: Mutex<u64> = Mutex::new(0);
unsafe {
let guard = GUARD.lock();
let mut counter = COUNTER.lock().unwrap_or_else(PoisonError::into_inner);
let Some(id) = counter.checked_add(1) else {
// in case the panic handler ends up calling `ThreadId::new()`,
// avoid reentrant lock acquire.
drop(counter);
exhausted();
};
let Some(id) = COUNTER.checked_add(1) else {
drop(guard); // in case the panic handler ends up calling `ThreadId::new()`, avoid reentrant lock acquire.
exhausted();
};
COUNTER = id;
drop(guard);
ThreadId(NonZeroU64::new(id).unwrap())
}
*counter = id;
drop(counter);
ThreadId(NonZeroU64::new(id).unwrap())
}
}
}