Replace manual Default impl with educe in tor-dirmgr

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

use educe::Educe;

use crate::{Error, Result};

/// A shareable mutable-ish optional reference to a an [`Arc`].

///

// We give this construction its own type to simplify its users, and make

// sure we don't hold the lock against any async suspend points.

#[derive(Debug)]

#[derive(Debug, Educe)]

#[educe(Default)]

pub(crate) struct SharedMutArc<T> {

    /// Locked reference to the current value.

    ///

    dir: RwLock<Option<Arc<T>>>,

}

impl<T> Default for SharedMutArc<T> {

    fn default() -> Self {

        Self::new()

    }

}

impl<T> SharedMutArc<T> {

    /// Construct a new empty SharedMutArc.

    pub(crate) fn new() -> Self {

        SharedMutArc {

            dir: RwLock::new(None),

        }

        SharedMutArc::default()

    }

    /// Replace the current value with `new_val`.