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pub(crate) struct SyncWrapper<T>(T);

impl<T> SyncWrapper<T> {
    /// Creates a new SyncWrapper containing the given value.
    ///
    /// # Examples
    ///
    /// ```ignore
    /// use hyper::common::sync_wrapper::SyncWrapper;
    ///
    /// let wrapped = SyncWrapper::new(42);
    /// ```
    pub(crate) fn new(value: T) -> Self {
        Self(value)
    }

    /// Acquires a reference to the protected value.
    ///
    /// This is safe because it requires an exclusive reference to the wrapper. Therefore this method
    /// neither panics nor does it return an error. This is in contrast to [`Mutex::get_mut`] which
    /// returns an error if another thread panicked while holding the lock. It is not recommended
    /// to send an exclusive reference to a potentially damaged value to another thread for further
    /// processing.
    ///
    /// [`Mutex::get_mut`]: https://doc.rust-lang.org/std/sync/struct.Mutex.html#method.get_mut
    ///
    /// # Examples
    ///
    /// ```ignore
    /// use hyper::common::sync_wrapper::SyncWrapper;
    ///
    /// let mut wrapped = SyncWrapper::new(42);
    /// let value = wrapped.get_mut();
    /// *value = 0;
    /// assert_eq!(*wrapped.get_mut(), 0);
    /// ```
    pub(crate) fn get_mut(&mut self) -> &mut T {
        &mut self.0
    }

    /// Consumes this wrapper, returning the underlying data.
    ///
    /// This is safe because it requires ownership of the wrapper, aherefore this method will neither
    /// panic nor does it return an error. This is in contrast to [`Mutex::into_inner`] which
    /// returns an error if another thread panicked while holding the lock. It is not recommended
    /// to send an exclusive reference to a potentially damaged value to another thread for further
    /// processing.
    ///
    /// [`Mutex::into_inner`]: https://doc.rust-lang.org/std/sync/struct.Mutex.html#method.into_inner
    ///
    /// # Examples
    ///
    /// ```ignore
    /// use hyper::common::sync_wrapper::SyncWrapper;
    ///
    /// let mut wrapped = SyncWrapper::new(42);
    /// assert_eq!(wrapped.into_inner(), 42);
    /// ```
    #[allow(dead_code)]
    pub(crate) fn into_inner(self) -> T {
        self.0
    }
}

// this is safe because the only operations permitted on this data structure require exclusive
// access or ownership
unsafe impl<T: Send> Sync for SyncWrapper<T> {}