PoisonError in std::sync - Rust
Description: A type of error which can be returned whenever a lock is acquired.

## PoisonError

# Struct PoisonError

1.0.0 · Source

    pub struct PoisonError<T> { /* private fields */ }

Expand description

A type of error which can be returned whenever a lock is acquired.

Both `Mutex`es and `RwLock`s are poisoned whenever a thread fails while the lock is held. The precise semantics for when a lock is poisoned is documented on each lock. For a lock in the poisoned state, unless the state is cleared manually, all future acquisitions will return this error.

## §Examples

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

    let mutex = Arc::new(Mutex::new(1));

    // poison the mutex
    let c_mutex = Arc::clone(&mutex);
    let _ = thread::spawn(move || {
        let mut data = c_mutex.lock().unwrap();
        *data = 2;
        panic!();
    }).join();

    match mutex.lock() {
        Ok(_) => unreachable!(),
        Err(p_err) => {
            let data = p_err.get_ref();
            println!("recovered: {data}");
        }
    };

## Implementations§

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### impl<T> PoisonError<T>

1.2.0 · Source

#### pub fn new(_data: T) -> PoisonError<T>

Available on non-`panic=unwind` only.

Creates a `PoisonError`.

This is generally created by methods like `Mutex::lock` or `RwLock::read`.

This method may panic if std was built with `panic="abort"`.

1.2.0 · Source

#### pub fn into_inner(self) -> T

Consumes this error indicating that a lock is poisoned, returning the associated data.

##### §Examples

    use std::collections::HashSet;
    use std::sync::{Arc, Mutex};
    use std::thread;

    let mutex = Arc::new(Mutex::new(HashSet::new()));

    // poison the mutex
    let c_mutex = Arc::clone(&mutex);
    let _ = thread::spawn(move || {
        let mut data = c_mutex.lock().unwrap();
        data.insert(10);
        panic!();
    }).join();

    let p_err = mutex.lock().unwrap_err();
    let data = p_err.into_inner();
    println!("recovered {} items", data.len());

1.2.0 · Source

#### pub fn get_ref(&self) -> &T

Reaches into this error indicating that a lock is poisoned, returning a reference to the associated data.

1.2.0 · Source

#### pub fn get_mut(&mut self) -> &mut T

Reaches into this error indicating that a lock is poisoned, returning a mutable reference to the associated data.

## Trait Implementations§

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### impl<T> Debug for PoisonError<T>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<T> Display for PoisonError<T>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<T> Error for PoisonError<T>

1.30.0 · Source§

#### fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any. Read more
1.0.0 · Source§

#### fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()
Read more
1.0.0 · Source§

#### fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
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#### fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (`error_generic_member_access` #99301)
Provides type-based access to context intended for error reports. Read more
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### impl<T> From<PoisonError<T>> for TryLockError<T>

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#### fn from(err: PoisonError<T>) -> TryLockError<T>

Converts to this type from the input type.

## Auto Trait Implementations§

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### impl<T> Freeze for PoisonError<T>
where T: Freeze,

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### impl<T> RefUnwindSafe for PoisonError<T>
where T: RefUnwindSafe,

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### impl<T> Send for PoisonError<T>
where T: Send,

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### impl<T> Sync for PoisonError<T>
where T: Sync,

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### impl<T> Unpin for PoisonError<T>
where T: Unpin,

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### impl<T> UnwindSafe for PoisonError<T>
where T: UnwindSafe,

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> ToString for T
where T: Display + ?Sized,

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#### fn to_string(&self) -> String

Converts the given value to a `String`. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.