Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Cleanup cloudabi mutexes and condvars #77657

Merged
merged 5 commits into from
Oct 16, 2020
Merged

Cleanup cloudabi mutexes and condvars #77657

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
e6d61ad
Use slice_as_mut_ptr instead of first_ptr_mut.
m-ou-se Oct 7, 2020
0f26578
Get rid of UnsafeCell<MaybeUninit>s in cloudabi mutex.
m-ou-se Oct 7, 2020
41066be
Get rid of UnsafeCell in cloudabi rwlock.
m-ou-se Oct 7, 2020
060e8cb
Get rid of raw pointers and UnsafeCell in cloudabi condvar.
m-ou-se Oct 7, 2020
b3be11e
Formatting.
m-ou-se Oct 7, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
41 changes: 18 additions & 23 deletions library/std/src/sys/cloudabi/condvar.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@
use crate::cell::UnsafeCell;
use crate::mem;
use crate::sync::atomic::{AtomicU32, Ordering};
use crate::sys::cloudabi::abi;
Expand All @@ -12,37 +11,36 @@ extern "C" {
}

pub struct Condvar {
condvar: UnsafeCell<AtomicU32>,
condvar: AtomicU32,
}

pub type MovableCondvar = Condvar;

unsafe impl Send for Condvar {}
unsafe impl Sync for Condvar {}

const NEW: Condvar =
Condvar { condvar: UnsafeCell::new(AtomicU32::new(abi::CONDVAR_HAS_NO_WAITERS.0)) };

impl Condvar {
pub const fn new() -> Condvar {
NEW
Condvar { condvar: AtomicU32::new(abi::CONDVAR_HAS_NO_WAITERS.0) }
}

pub unsafe fn init(&mut self) {}

pub unsafe fn notify_one(&self) {
let condvar = self.condvar.get();
if (*condvar).load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
let ret = abi::condvar_signal(condvar as *mut abi::condvar, abi::scope::PRIVATE, 1);
if self.condvar.load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
let ret = abi::condvar_signal(
&self.condvar as *const AtomicU32 as *mut abi::condvar,
abi::scope::PRIVATE,
1,
);
assert_eq!(ret, abi::errno::SUCCESS, "Failed to signal on condition variable");
}
}

pub unsafe fn notify_all(&self) {
let condvar = self.condvar.get();
if (*condvar).load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
if self.condvar.load(Ordering::Relaxed) != abi::CONDVAR_HAS_NO_WAITERS.0 {
let ret = abi::condvar_signal(
condvar as *mut abi::condvar,
&self.condvar as *const AtomicU32 as *mut abi::condvar,
abi::scope::PRIVATE,
abi::nthreads::MAX,
);
Expand All @@ -53,20 +51,19 @@ impl Condvar {
pub unsafe fn wait(&self, mutex: &Mutex) {
let mutex = mutex::raw(mutex);
assert_eq!(
(*mutex).load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
mutex.load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
__pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
"This lock is not write-locked by this thread"
);

// Call into the kernel to wait on the condition variable.
let condvar = self.condvar.get();
let subscription = abi::subscription {
type_: abi::eventtype::CONDVAR,
union: abi::subscription_union {
condvar: abi::subscription_condvar {
condvar: condvar as *mut abi::condvar,
condvar: &self.condvar as *const AtomicU32 as *mut abi::condvar,
condvar_scope: abi::scope::PRIVATE,
lock: mutex as *mut abi::lock,
lock: mutex as *const AtomicU32 as *mut abi::lock,
lock_scope: abi::scope::PRIVATE,
},
},
Expand All @@ -86,23 +83,22 @@ impl Condvar {
pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
let mutex = mutex::raw(mutex);
assert_eq!(
(*mutex).load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
mutex.load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
__pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
"This lock is not write-locked by this thread"
);

// Call into the kernel to wait on the condition variable.
let condvar = self.condvar.get();
let timeout =
checked_dur2intervals(&dur).expect("overflow converting duration to nanoseconds");
let subscriptions = [
abi::subscription {
type_: abi::eventtype::CONDVAR,
union: abi::subscription_union {
condvar: abi::subscription_condvar {
condvar: condvar as *mut abi::condvar,
condvar: &self.condvar as *const AtomicU32 as *mut abi::condvar,
condvar_scope: abi::scope::PRIVATE,
lock: mutex as *mut abi::lock,
lock: mutex as *const AtomicU32 as *mut abi::lock,
lock_scope: abi::scope::PRIVATE,
},
},
Expand All @@ -124,7 +120,7 @@ impl Condvar {
let mut nevents: mem::MaybeUninit<usize> = mem::MaybeUninit::uninit();
let ret = abi::poll(
subscriptions.as_ptr(),
mem::MaybeUninit::first_ptr_mut(&mut events),
mem::MaybeUninit::slice_as_mut_ptr(&mut events),
2,
nevents.as_mut_ptr(),
);
Expand All @@ -144,9 +140,8 @@ impl Condvar {
}

pub unsafe fn destroy(&self) {
let condvar = self.condvar.get();
assert_eq!(
(*condvar).load(Ordering::Relaxed),
self.condvar.load(Ordering::Relaxed),
abi::CONDVAR_HAS_NO_WAITERS.0,
"Attempted to destroy a condition variable with blocked threads"
);
Expand Down
54 changes: 25 additions & 29 deletions library/std/src/sys/cloudabi/mutex.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
use crate::cell::UnsafeCell;
use crate::cell::Cell;
use crate::mem;
use crate::mem::MaybeUninit;
use crate::sync::atomic::{AtomicU32, Ordering};
Expand All @@ -17,7 +17,7 @@ pub struct Mutex(RWLock);

pub type MovableMutex = Mutex;

pub unsafe fn raw(m: &Mutex) -> *mut AtomicU32 {
pub unsafe fn raw(m: &Mutex) -> &AtomicU32 {
rwlock::raw(&m.0)
}

Expand Down Expand Up @@ -50,28 +50,23 @@ impl Mutex {
}

pub struct ReentrantMutex {
lock: UnsafeCell<MaybeUninit<AtomicU32>>,
recursion: UnsafeCell<MaybeUninit<u32>>,
lock: AtomicU32,
recursion: Cell<u32>,
}

unsafe impl Send for ReentrantMutex {}
unsafe impl Sync for ReentrantMutex {}

impl ReentrantMutex {
pub const unsafe fn uninitialized() -> ReentrantMutex {
ReentrantMutex {
lock: UnsafeCell::new(MaybeUninit::uninit()),
recursion: UnsafeCell::new(MaybeUninit::uninit()),
}
ReentrantMutex { lock: AtomicU32::new(abi::LOCK_UNLOCKED.0), recursion: Cell::new(0) }
}

pub unsafe fn init(&self) {
*self.lock.get() = MaybeUninit::new(AtomicU32::new(abi::LOCK_UNLOCKED.0));
*self.recursion.get() = MaybeUninit::new(0);
}
pub unsafe fn init(&self) {}

pub unsafe fn try_lock(&self) -> bool {
// Attempt to acquire the lock.
let lock = (*self.lock.get()).as_mut_ptr();
let recursion = (*self.recursion.get()).as_mut_ptr();
if let Err(old) = (*lock).compare_exchange(
if let Err(old) = self.lock.compare_exchange(
abi::LOCK_UNLOCKED.0,
__pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
Ordering::Acquire,
Expand All @@ -80,22 +75,22 @@ impl ReentrantMutex {
// If we fail to acquire the lock, it may be the case
// that we've already acquired it and may need to recurse.
if old & !abi::LOCK_KERNEL_MANAGED.0 == __pthread_thread_id.0 | abi::LOCK_WRLOCKED.0 {
*recursion += 1;
self.recursion.set(self.recursion.get() + 1);
true
} else {
false
}
} else {
// Success.
assert_eq!(*recursion, 0, "Mutex has invalid recursion count");
assert_eq!(self.recursion.get(), 0, "Mutex has invalid recursion count");
true
}
}

pub unsafe fn lock(&self) {
if !self.try_lock() {
// Call into the kernel to acquire a write lock.
let lock = self.lock.get();
let lock = &self.lock as *const AtomicU32;
let subscription = abi::subscription {
type_: abi::eventtype::LOCK_WRLOCK,
union: abi::subscription_union {
Expand All @@ -116,17 +111,17 @@ impl ReentrantMutex {
}

pub unsafe fn unlock(&self) {
let lock = (*self.lock.get()).as_mut_ptr();
let recursion = (*self.recursion.get()).as_mut_ptr();
assert_eq!(
(*lock).load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
self.lock.load(Ordering::Relaxed) & !abi::LOCK_KERNEL_MANAGED.0,
__pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
"This mutex is locked by a different thread"
);

if *recursion > 0 {
*recursion -= 1;
} else if !(*lock)
let r = self.recursion.get();
if r > 0 {
self.recursion.set(r - 1);
} else if !self
.lock
.compare_exchange(
__pthread_thread_id.0 | abi::LOCK_WRLOCKED.0,
abi::LOCK_UNLOCKED.0,
Expand All @@ -137,19 +132,20 @@ impl ReentrantMutex {
{
// Lock is managed by kernelspace. Call into the kernel
// to unblock waiting threads.
let ret = abi::lock_unlock(lock as *mut abi::lock, abi::scope::PRIVATE);
let ret = abi::lock_unlock(
&self.lock as *const AtomicU32 as *mut abi::lock,
abi::scope::PRIVATE,
);
assert_eq!(ret, abi::errno::SUCCESS, "Failed to unlock a mutex");
}
}

pub unsafe fn destroy(&self) {
let lock = (*self.lock.get()).as_mut_ptr();
let recursion = (*self.recursion.get()).as_mut_ptr();
assert_eq!(
(*lock).load(Ordering::Relaxed),
self.lock.load(Ordering::Relaxed),
abi::LOCK_UNLOCKED.0,
"Attempted to destroy locked mutex"
);
assert_eq!(*recursion, 0, "Recursion counter invalid");
assert_eq!(self.recursion.get(), 0, "Recursion counter invalid");
}
}
Loading