Struct FRAME_INFO

pub struct FRAME_INFO { /* private fields */ }

Available on non-WebAssembly only.

This is a global cache of backtrace frame information for all active

This global cache is used during Trap creation to symbolicate frames. This is populated on module compilation, and it is cleared out whenever all references to a module are dropped.

Methods from Deref<Target = RwLock<GlobalFrameInfo>>

pub fn get_cloned(&self) -> Result<T, PoisonError<()>>

where T: Clone,

🔬This is a nightly-only experimental API. (lock_value_accessors)

Available on crate feature std only.

Returns the contained value by cloning it.

Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.get_cloned().unwrap(), 7);

pub fn set(&self, value: T) -> Result<(), PoisonError<T>>

🔬This is a nightly-only experimental API. (lock_value_accessors)

Available on crate feature std only.

Sets the contained value.

Errors

This function will return an error containing the provided value if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.get_cloned().unwrap(), 7);
lock.set(11).unwrap();
assert_eq!(lock.get_cloned().unwrap(), 11);

pub fn replace(&self, value: T) -> Result<T, PoisonError<T>>

🔬This is a nightly-only experimental API. (lock_value_accessors)

Available on crate feature std only.

Replaces the contained value with value, and returns the old contained value.

Errors

This function will return an error containing the provided value if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock.

Examples

#![feature(lock_value_accessors)]

use std::sync::RwLock;

let mut lock = RwLock::new(7);

assert_eq!(lock.replace(11).unwrap(), 7);
assert_eq!(lock.get_cloned().unwrap(), 11);

pub fn read( &self, ) -> Result<RwLockReadGuard<'_, T>, PoisonError<RwLockReadGuard<'_, T>>>

Available on crate feature std only.

Locks this RwLock with shared read access, blocking the current thread until it can be acquired.

The calling thread will be blocked until there are no more writers which hold the lock. There may be other readers currently inside the lock when this method returns. This method does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

Returns an RAII guard which will release this thread’s shared access once it is dropped.

Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. The failure will occur immediately after the lock has been acquired. The acquired lock guard will be contained in the returned error.

Panics

This function might panic when called if the lock is already held by the current thread.

Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(1));
let c_lock = Arc::clone(&lock);

let n = lock.read().unwrap();
assert_eq!(*n, 1);

thread::spawn(move || {
    let r = c_lock.read();
    assert!(r.is_ok());
}).join().unwrap();

pub fn try_read( &self, ) -> Result<RwLockReadGuard<'_, T>, TryLockError<RwLockReadGuard<'_, T>>>

Available on crate feature std only.

Attempts to acquire this RwLock with shared read access.

If the access could not be granted at this time, then Err is returned. Otherwise, an RAII guard is returned which will release the shared access when it is dropped.

This function does not block.

This function does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

Errors

This function will return the Poisoned error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. Poisoned will only be returned if the lock would have otherwise been acquired. An acquired lock guard will be contained in the returned error.

This function will return the WouldBlock error if the RwLock could not be acquired because it was already locked exclusively.

Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

match lock.try_read() {
    Ok(n) => assert_eq!(*n, 1),
    Err(_) => unreachable!(),
};

pub fn write( &self, ) -> Result<RwLockWriteGuard<'_, T>, PoisonError<RwLockWriteGuard<'_, T>>>

Available on crate feature std only.

Locks this RwLock with exclusive write access, blocking the current thread until it can be acquired.

This function will not return while other writers or other readers currently have access to the lock.

Returns an RAII guard which will drop the write access of this RwLock when dropped.

Errors

This function will return an error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. An error will be returned when the lock is acquired. The acquired lock guard will be contained in the returned error.

Panics

This function might panic when called if the lock is already held by the current thread.

Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

let mut n = lock.write().unwrap();
*n = 2;

assert!(lock.try_read().is_err());

pub fn try_write( &self, ) -> Result<RwLockWriteGuard<'_, T>, TryLockError<RwLockWriteGuard<'_, T>>>

Available on crate feature std only.

Attempts to lock this RwLock with exclusive write access.

If the lock could not be acquired at this time, then Err is returned. Otherwise, an RAII guard is returned which will release the lock when it is dropped.

This function does not block.

This function does not provide any guarantees with respect to the ordering of whether contentious readers or writers will acquire the lock first.

Errors

This function will return the Poisoned error if the RwLock is poisoned. An RwLock is poisoned whenever a writer panics while holding an exclusive lock. Poisoned will only be returned if the lock would have otherwise been acquired. An acquired lock guard will be contained in the returned error.

This function will return the WouldBlock error if the RwLock could not be acquired because it was already locked exclusively.

Examples

use std::sync::RwLock;

let lock = RwLock::new(1);

let n = lock.read().unwrap();
assert_eq!(*n, 1);

assert!(lock.try_write().is_err());

pub fn is_poisoned(&self) -> bool

Available on crate feature std only.

Determines whether the lock is poisoned.

If another thread is active, the lock can still become poisoned at any time. You should not trust a false value for program correctness without additional synchronization.

Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(0));
let c_lock = Arc::clone(&lock);

let _ = thread::spawn(move || {
    let _lock = c_lock.write().unwrap();
    panic!(); // the lock gets poisoned
}).join();
assert_eq!(lock.is_poisoned(), true);

pub fn clear_poison(&self)

Available on crate feature std only.

Clear the poisoned state from a lock.

If the lock is poisoned, it will remain poisoned until this function is called. This allows recovering from a poisoned state and marking that it has recovered. For example, if the value is overwritten by a known-good value, then the lock can be marked as un-poisoned. Or possibly, the value could be inspected to determine if it is in a consistent state, and if so the poison is removed.

Examples

use std::sync::{Arc, RwLock};
use std::thread;

let lock = Arc::new(RwLock::new(0));
let c_lock = Arc::clone(&lock);

let _ = thread::spawn(move || {
    let _lock = c_lock.write().unwrap();
    panic!(); // the lock gets poisoned
}).join();

assert_eq!(lock.is_poisoned(), true);
let guard = lock.write().unwrap_or_else(|mut e| {
    **e.get_mut() = 1;
    lock.clear_poison();
    e.into_inner()
});
assert_eq!(lock.is_poisoned(), false);
assert_eq!(*guard, 1);

Trait Implementations

impl Deref for FRAME_INFO

type Target = RwLock<GlobalFrameInfo>

The resulting type after dereferencing.

fn deref(&self) -> &RwLock<GlobalFrameInfo>

Dereferences the value.

impl LazyStatic for FRAME_INFO