# Struct lock_api::MappedReentrantMutexGuard [−] [src]

    #[must_use = "if unused the ReentrantMutex will immediately unlock"]pub struct MappedReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { /* fields omitted */ }

An RAII mutex guard returned by `ReentrantMutexGuard::map`, which can point to a subfield of the protected data.

The main difference between `MappedReentrantMutexGuard` and `ReentrantMutexGuard` is that the former doesn’t support temporarily unlocking and re-locking, since that could introduce soundness issues if the locked object is modified by another thread.

## Implementations

### `impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> MappedReentrantMutexGuard<'a, R, G, T>` [src]

#### `pub fn map<U: ?Sized, F>(
s: Self,
f: F
) -> MappedReentrantMutexGuard<'a, R, G, U> where
F: FnOnce(&T) -> &U,` [src]

Makes a new `MappedReentrantMutexGuard` for a component of the locked data.

This operation cannot fail as the `MappedReentrantMutexGuard` passed in already locked the mutex.

This is an associated function that needs to be used as `MappedReentrantMutexGuard::map(...)`. A method would interfere with methods of the same name on the contents of the locked data.

#### `pub fn try_map<U: ?Sized, F>(
s: Self,
f: F
) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self> where
F: FnOnce(&T) -> Option<&U>,` [src]

Attempts to make a new `MappedReentrantMutexGuard` for a component of the locked data. The original guard is return if the closure returns `None`.

This operation cannot fail as the `MappedReentrantMutexGuard` passed in already locked the mutex.

This is an associated function that needs to be used as `MappedReentrantMutexGuard::map(...)`. A method would interfere with methods of the same name on the contents of the locked data.

### `impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> MappedReentrantMutexGuard<'a, R, G, T>` [src]

#### `pub fn unlock_fair(s: Self)` [src]

Unlocks the mutex using a fair unlock protocol.

By default, mutexes are unfair and allow the current thread to re-lock the mutex before another has the chance to acquire the lock, even if that thread has been blocked on the mutex for a long time. This is the default because it allows much higher throughput as it avoids forcing a context switch on every mutex unlock. This can result in one thread acquiring a mutex many more times than other threads.

However in some cases it can be beneficial to ensure fairness by forcing the lock to pass on to a waiting thread if there is one. This is done by using this method instead of dropping the `ReentrantMutexGuard` normally.

## Trait Implementations

### `impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: Debug + ?Sized + 'a> Debug for MappedReentrantMutexGuard<'a, R, G, T>` [src]

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

Formats the value using the given formatter. Read more

### `impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref for MappedReentrantMutexGuard<'a, R, G, T>` [src]

#### `type Target = T`

The resulting type after dereferencing.

#### `fn deref(&self) -> &T` [src]

Dereferences the value.

### `impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: Display + ?Sized + 'a> Display for MappedReentrantMutexGuard<'a, R, G, T>` [src]

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

Formats the value using the given formatter. Read more

### `impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop for MappedReentrantMutexGuard<'a, R, G, T>` [src]

#### `fn drop(&mut self)` [src]

Executes the destructor for this type. Read more

### `impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync for MappedReentrantMutexGuard<'a, R, G, T>` [src]

## Auto Trait Implementations

### `impl<'a, R, G, T> !Send for MappedReentrantMutexGuard<'a, R, G, T>`

### `impl<'a, R, G, T: ?Sized> Unpin for MappedReentrantMutexGuard<'a, R, G, T>`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.