Struct spin::Mutex
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pub struct Mutex<T: ?Sized> { /* fields omitted */ }
This type provides MUTual EXclusion based on spinning.
Description
This structure behaves a lot like a normal Mutex. There are some differences:
- It may be used outside the runtime.
- A normal mutex will fail when used without the runtime, this will just lock
- When the runtime is present, it will call the deschedule function when appropriate
- No lock poisoning. When a fail occurs when the lock is held, no guarantees are made
When calling rust functions from bare threads, such as C pthread
s, this lock will be very
helpful. In other cases however, you are encouraged to use the locks from the standard
library.
Simple examples
use spin; let spin_mutex = spin::Mutex::new(0); // Modify the data { let mut data = spin_mutex.lock(); *data = 2; } // Read the data let answer = { let data = spin_mutex.lock(); *data }; assert_eq!(answer, 2);
Thread-safety example
use spin; use std::sync::{Arc, Barrier}; let numthreads = 1000; let spin_mutex = Arc::new(spin::Mutex::new(0)); // We use a barrier to ensure the readout happens after all writing let barrier = Arc::new(Barrier::new(numthreads + 1)); for _ in (0..numthreads) { let my_barrier = barrier.clone(); let my_lock = spin_mutex.clone(); std::thread::spawn(move|| { let mut guard = my_lock.lock(); *guard += 1; // Release the lock to prevent a deadlock drop(guard); my_barrier.wait(); }); } barrier.wait(); let answer = { *spin_mutex.lock() }; assert_eq!(answer, numthreads);
Methods
impl<T> Mutex<T>
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pub const fn new(user_data: T) -> Mutex<T>
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Creates a new spinlock wrapping the supplied data.
May be used statically:
#![feature(const_fn)] use spin; static MUTEX: spin::Mutex<()> = spin::Mutex::new(()); fn demo() { let lock = MUTEX.lock(); // do something with lock drop(lock); }
pub fn into_inner(self) -> T
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Consumes this mutex, returning the underlying data.
impl<T: ?Sized> Mutex<T>
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pub fn lock(&self) -> MutexGuard<T>
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Locks the spinlock and returns a guard.
The returned value may be dereferenced for data access and the lock will be dropped when the guard falls out of scope.
let mylock = spin::Mutex::new(0); { let mut data = mylock.lock(); // The lock is now locked and the data can be accessed *data += 1; // The lock is implicitly dropped }
pub unsafe fn force_unlock(&self)
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Force unlock the spinlock.
This is extremely unsafe if the lock is not held by the current thread. However, this can be useful in some instances for exposing the lock to FFI that doesn't know how to deal with RAII.
If the lock isn't held, this is a no-op.
pub fn try_lock(&self) -> Option<MutexGuard<T>>
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Tries to lock the mutex. If it is already locked, it will return None. Otherwise it returns a guard within Some.
Trait Implementations
impl<T: ?Sized + Send> Sync for Mutex<T>
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impl<T: ?Sized + Send> Send for Mutex<T>
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impl<T: ?Sized + Debug> Debug for Mutex<T>
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fn fmt(&self, f: &mut Formatter) -> Result
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Formats the value using the given formatter. Read more